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BIHANG
TILL
KONGL. SVENSKA VETENSKAPS-AKADENITENS
HANDLINGAR.
ADERTONDE BANDET.
AFDELNING IV.
ZOOLOGI, OMFATTANDE BÅDE LEFVANDE OCH FOSSILA FORMER.
STOCKHOLM 1893. P. A. NORSTEDT & SÖNER.
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INNEHÅLL AF ADERTONDE BANDET.
Afdelning IV.
(Zoologi, omfattande både lefvande och fossila former).
SRMOVENs S:T fuechinolögicea. Withol2 plates ssccc. scos-sc-s skesssesssEsseres
SIRLONNERRG, 10: Ichthyologisehe Notizen. Il aosstsssos--cs-t-s-sosess=-so==
-
. AURIVILLIUS, CARL. Ueber einige obersilurische Cirripeden aus Got-
ibrjigöle — IVRe (109 (Era La ST AR Set AE EIS SETS NSI SA SAR NEN ARE
. BERGENDAL, D. Gastroschiza triacantha n. g. n. sp., eine neue Gat-
tung und Familie der Räderthiere. Mit 2 Tafeln..-.soss-:-s-------
. GULLSTRAND, A. Objective Differentialdiagnostik und photogra-
phische Abbildung von Augenmuskellähmungen. Mit 15 Tafeln...
. LÖNNBERG, E. Bemerkungen iber einige Cestoden. Mit einer Tafel . VON PoraAT, C. O. Myriopoder från Vest- och Syd-Afrika........----- . HOLMGREN, E. Några ord om körtelinnervationer och körtelkapil-
larer hos lepidopterlarver, samt om ett egendomligt muskelslag
hos dessa senares sfinkterbildningar. Med en tafla.........o....-----
Sid. 1—74 1—13. 1—24. 1—22 1—39 1—17 1—532 1—211.
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BIHANG TILL K. SVENSKA VET.-AKAD. HANDLINGAR. Band 18: Afd IV. N:o I.
HCHTINOLOGICA
SVEN LOVÉN.
WITH TWELYE PLEATES.
COMMUNICATED TO THE R. SWEDISH ACADEMY OF SCIENCES DECEMBER 11"", 1889 AND: JANUARY 13" 1892.
STOCKHOLM 1892.
KUNGL. BOKTRYCKERIET. P. A. NORSTEDT & SÖNER.
VEN ÄN RE IE 6 OM
| ved ALM E - Py Ty 1 : 5 | i & 3 1” kh ua få HW
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äs Echinoid, such as it is when it has just ended its larval period and assumed the outward form of the adult, has been described from time to time, the Arbacia zequituberculata BLv. and the A. punctulata LAMCcK by JOHANNES MULLER! ÅLEX- ANDER ÅGASSIZ? and GARMAN and CoLToN?; the Strongylocentrus dröbakensis O. F. M. by ÅL. AGassiIzt; the Strongylocentrus lividus LAMcK by KRoHN'; the Echinus parvituberculatus BLv. by Bury; the Echinarachnius Parma LaAMcK by FEWKES? and besides these other: doubtful or unknown species3. TI for- merly observed a young specimen of some northern form?, and had the drawings made which are repeated here p. 11. In these several instances the final form takes its existence not from an egg but from the interior of a larva, the plu- teus, which is itself the direct issue of an egg and after a short free-swimming life has its frame consumed in ori- ginating the imago. From this general process of indirect development two exceptions are known in which the free- swimming stage is left out, be it that surrounding agencies in some manner have rendered the metamorphosis superfluous, perhaps dangerous, or that they represent an order of things else antiquated, or a new era of simplified development. They are: a Spatangid, Abatus cavernosus PuHIL.!, and a Cidarid,
! Metamorphose d. Echinodermen, VII, 1855, p. 22, Pl. IV, fig. 3, 4.
? Revision, 1874, p. 734, fig. 68, 69.
3 BrRooKs, Handbook of Invertebrate Zoology, 1882, p. 130, fig. 76, 77.
+ Embryology of Echinoderms, Mem. Amer. Acad., IX, 1864, pl. 1; Revi- StONPp: 02, Pl INVfSRUTPINN, fe; 14
5 MöLLERsS Archiv, 1851, p. 351.
& Quart. Journ. Microsc. Science, N. S., XXIX, p. 439, P1. XXXVIII, fig. 11.
7 Bull. Mus. Comp. Zool., XII, p. 120. P1. II—VIII, 1886.
3 JOHANNES MÖLLER, Metamorphose, I, 1848, p. 23, P1. VII, fig. 1—11. Ib: VII 1855,1p. 257 Pl. VIL figi8=10.
? Etudes s: 1. Echinoidées, 1874, p. 27, P1. XVII, fig. 149 - 152. — Pour- TAlesia; pi 20, Pl XIX Hg. 232, 200.
!0 PHiuIPPI, Wgm.. Arch., XI, 1845, p. 346. — AL: AGAssiz, Proc. Amer. Acad.; XI, 1876, p. 231; Challenger Ech., 1881, p. 179, P1. XX"; fig. 1; 2; 7— 10. — Wyv. THOMSON, Voy. Chall., II, 1877, p. 229, woodeut p. 233. STU- DER, Berlin. Mon. Ber., Juli 1876, p. 457; ib.. October 1880, p. 881; Zool. An- zeiger, 1880, p. 67, 68.
4 SVEN LOVÉN, RECHINOLOGICA.
Goniocidaris canaliculata AL. AG.!, both living in the Antarc- tie seas. A third form, the highly anomalous Anochanus GRUBE?, of the China Sea, is as yet but imperfectly known. In the Abatus the eggs emitted through the sexual aper- tures of the mother are received into the deep recesses of her petals. Their development has not been followed through its different stages, but from the fact that ÅLEXANDER ÅGASSIZ found the marsupium replete with fully developed young ones, and since a specimen I once describedåiwas found lying at the very bottom of the petal under a erowded multitude of newly- ejeeted eggs, it follows that the development is performed entirely within the marsupium and that no free-swimming pluteal stage exists. The young Abatus? measured 2,3 mm. in length, 1,9 mm. in breadth, and clearly was not far from leaving the nursery. Its general form is nearly that of the parent. It is still without oral and excretory apertures. "The whole body, spines and all, is tightly enveloped with a thick membraneous covering, the larval covering, apparently the re- presentative of an abridged and transitory pluteus-stage. With- im this envelope the spines are already strong and the plates of the calcified skeleton distinct, ambulacral as well as inter- radial. But there are two clear spaces, both overspread by the general covering: the one on the ventral side being the pentagonal stoma of the coronal system, the other, dorsal, the central part of the calycinal system. The intestine is still cecal at both ends. The closed oral termination touches the wall of the visceral cavity at the centre of the stoma?. Right over it the excretorial end, in passing towards its future po- sterior position in the interradium 5, moves backwards along the inner surface of the calyx, and causes the calcified cen- tral piece and the costals to be partly reabsorbed and fractured, while the five radials, each with its still large provisional sucker, remain intact?, an effect of disintegration of the calyx and dorsal part of the test seen to accompany the movements of the intestine during more than one of the phases of phylo-
! StTUDER, Berlin. Mon. Ber. Juni 1876, p. 455. — Wyv. THOMSON, Voy. Chall. II, 1877, p. 226, woodcut, p. 224, 227. — AL. AGassiz Chall. Echin., 1881) pr 45 PIC fe: re, 9, sLÖNES:
> Berlin. Mon. Ber., April 1868, p. 178.
> Compare the author's memoir on Pourtalesia, p. 20, 25, P1. XIV, fig. 163 —171; woodeut, p. 26.
tie: cfigT 10505, IGT
>] ec fig. 1647 I640A, 1667 168:
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0 1. »)
genetic development among Echinoidea!. When the csopha- geal end of the intestine has pierced the membrane that covers the stoma”?, and the periproct has been formed in the inter- radium 5, then the post-pluteal stage is finished and its five provisional sucking-feet are no more seen.
WYVILLE "THOMSON relates of the Goniocidaris canaliculata AL. AG., dredged at the Falkland Islands?, that its young were observed to creep upon the spines of the parent by the aid of their five huge provisional suckers. On a specimen of this species, caught at the same occasion, and for which I am indebted to Mr JoHns Murray, I found a few young ones, the examination of which afforded the following additional obser- vations. They have been described and figured long ago by ALEXANDER ÅGASSIZ?.
The voung seem to be all of the same age, though some are more advanced than others. The diameter, exclusive of the spines, is between 1,45 mm. and 1,7 mm. "The test is consi- derably more depressed than that of the parent, its height hardly equalling half the diameter.
The specimen figured Pl. I, fig. 1 may be taken as an example of the least advanced. Its spines are relatively short. The five provisional suckers are very strong, acetabulated, longer than the spines and, although contracted, reach consi- derably downwards. "Phere are five pairs of persistent pedi- cels in every ambulaerum, and some tongs. Seen from above the calycinal system of another specimen, Pl. IT, fig. 3, shows its radials and costals. The radials are lengthened and com- pressed; at the outer end of each of them the external integu- ment is produced into a provisional sucker, fig. 4, the ducts of which communicate with the interior by means of a pas- sage sheltered by the vaulted adoral margin of the radial. The costals are large, somewhat irregular, each with a small, nearly central spine, and the one of the interradial 2 is per- forated by a large water-pore, the precedent of the future madreporite. In the centre there is a small, clear, irregularly
! Etudes P1. XI, fig. 93—97; P1. XXIII, fig. 180, 181; Pourtalesia p. 70, on the Ethmophracti among the Spatangide.
? Pourtalesia, p. 26; compare Etudes s. 1. Echinoidées p. 14, P1. III, fig. 32, 33.
3 Voyage of the Challenger, II, p. 223.
+ Challenger Rep. Echin., p. 45, P1. II, fig. 9, 10, 18.
6 SVEN LOVÉN, ECHINOLOGICA.
pentagonal space, covered by the general integument. In an- other specimen, fig. 5, this space has just been filled with the dorso-central disk, fig. 6, a still delicate pentagonal lamina of reticulated calcified tissue, with its thin margins now over- lying, now underlying those of the costals, in its middle thic- kened and raised into the beginnings of a verruca. In the specimen, Pl. I, fig. 2, the most advanced, the sutures are di- stinetly seen through the covering, and the dorso-central disk is well defined. ”The five provisional suckers are here strongly contracted, seemingly preparing to disappear, as observed long ago by the late Aveuvstus KroHn.! All over the corona a small number of secondary spines are present, but, what is remarkable, there are only two on every interradial plate, and in this specimen as well as in the others there is no trace of the circles of flattened secondaries, which in the adult sur- round the bases of the primary spines. "This is also clearly seen in another specimen of the same age 1,45 mm. in diame- ter, carefully dried and denuded, Pl. II fig. 7, 8, 9. The dorso- central disk of the calycinal system is distinct and, like the five costals, presents a single verruca, while the large and convex costal, that gives passage to the water-pore, bears three to four. The radials, which appear to be somewhat shortened and are provided each with a verruca, have the aper- ture at the base of the sucker closed on its under side, fig. 8.
At this age the ambulacra enter into the composition of the coronal system with five pairs of plates, fig. 8, 9. The innermost of these, the five primordial pairs, are large, some- what wedge-shaped, closely contiguous to one another, and constitute by themselves alone the first cirele. A solution of continuity is clearly seen to intervene between them and the following pairs. These, the second to the fifth, form, as a whole, the ambulacral constituents of the corona, fig. 8. They are smaller, distinetly hexagonal, and nearly twice as high as they are broad. All the plates of the ambulacra are pier- ced each with a pedicellar pore, and in all respects disposed according to the law of heterotropy? maintained in the whole
' MörrL. Arch. 1851, p. 351. — It is also worth remembering that, ten years before, this acute observer had seen the ambulacral nerve pass tbrough the pore into the pedicel, and there up to the sucking-disk. Mörr. Archiv, 1841, p. 6.
> Etudes s. 1. Echinoidées, p. 13 — 39, P1. III—IX, XIV, XVII—XX, XXTII-—-LII. — Pourtalesia p. 6, 34.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:O 1. TY
of the Echinoidea, the Pourtalesiadee excepted. Thus, of the pömordialk' plates, j2g.s9; the l a IF a; ITIL bb) TV Gö Vi b-are distinetly larger than the I b, II b, IIT a, IV b, V a, while in each of the five second pairs the plates of the former se- ries are less advanced than those of the latter. From these inequalities there arises, at this early stage, a deviation from the cireular disposition more obvious in the dextral half, I a—III «4, and caused by the detached II a pressing on the point of contact between the interradium 1 and the small ENE
The interradial plates are hexagonal, somewhat broader than they are high, large, convex, each provided with a pri- mary, distinetly perforated verruca. They are all contiguous within every column. Every interradium consists of four pairs of alternating plates and one primordial, peristomal plate, broad and well-developed, fig. 9.1 This solitary adoral is ex- cluded from the first and innermost coronal cirele, but enters into the second. which consequently comes to be formed of ten second binary ambulacrals and five primordial solitary inter- radials. This is the normal constitution of the peristome in the whole class.
The space encireled by the adoral ends of the ten primary ambulacrals, in the centre of which the lip will come to sur- round the future mouth, is at this stage closed over by the covering membrane. In the dried specimen, fig. 9, this has been drawn in into the opening. It is transparent and from under the adoral ends of the primordial ambulacrals are seen pro- truding those of the pyramids, the two halves of each roun- ded, interradial, but no teeth are visible.
One of the less advanced specimens, the same which af- forded the fig 3, was cut open horizontally so as to show the alimentary canal, the intestine proper, the csophagus and the rectum, Fl. III, fig. 10, 71, 12. The intestine is suspen- ded over the still flatly expanded dental apparatus, fig. 11, and has the shape of an oblong bag bent upon itself almost horizontally into a pentangularly circular form, fig. 10, the middle of its great curvature answering to the suture V, 4, while the somewhat narrowed terminations meet near the su- ture II, 2. Its dorsal surface, fig. 10, is convex, even, not
! First observed by DÖDERLEIN, Japanische Seeigel, p. 32, P1 IX, fig. b,
pv, F.
la SVEN LOVÉN, ECHINOLOGICA.
sacculated, the ventral, fig. 12, concave in the middle, exte- riorly thick and convex all around, slightly swelling interra- dially, and feebly narrowed and plicated opposite the ambu- lacra. The anterior, cardiac termination, a, near the 2, pro- jects a little beyond the point where the cosophagus, &s., nar- row and straight, descends obliquely towards the centre of the dental apparatus, fiy. 10, while at the other, the posterior end, p. near II a, the rectum, r, abruptly contracted, ascends obli- quely towards the centre of the calycinal system, fig. 10, 11.
I am obliged to the kindness of Miss SIGRID ANDERSSON for a continuous series of numerous vertical sections of this intestine, as well as for another series prepared with equal skill, of horizontal sections of an entire young animal a little more advanced. From the first of these series the six sections were selected which afforded the fig. 13 to 18. They show that at this period the wall of the intestine, a thick and so- lid cellular mass, encloses an utterly narrow lumen, its dorsal and ventral portions being all but contiguous, leaving between them a small open space along the sides only. In fig. 15 the prominent cardiac portion is seen, from which the csophagus proceeds, and in fig. 17 the rectum going off from near the posterior end. Among the horizontal sections one, fiy. 19, shows the inner surface of the intestine and one of the me- senterial bands; fig. 20 the csophagus, and in the interval between the two ends of the intestine, the aquiferous canal, the ovoid gland, and the blood-lacunes in connection, fig. 10, 11"; fig. 21 the rectum. 'The entire alimentary canal is empty and functionless.
When the intestine had been removed and the dental ap- paratus brought into view, this was found far from being in working order, fig. 22. 'The pyramids are widely distant from one another, and of each, the two halves, 75, while ap- proaching adorally, diverge ontwards and at the same time recline almost horizontally upon the inside of the test, fig. 11,
IT.
22. Each half pyramid, ”5', is a thick, oblong mass of reticular tissue on the way of calcifying, produced adorally at its inner margin. Between every two of these halves is seen, interra- dially, one of the five teeth, which in this aspect presents a somewhat pear-shaped outline, its aboral part being broad, convex and rounded, the adoral acuminate and marginally
spinous; it is smooth, and its homogeneous texture strikingly
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0 1. 9
contrasts with that of the pyramid! At the aboral end of each half-pyramid is seen laterally a small aggregation of coarser reticular tissue, the commencement of the epiphysis JOHANNES MÖLLER, STEWART (arcus VALENTIN), and in the middle between every two pyramids a still more simple rudiment probably of the rotula DEsMoULINS, JOH. MÖLLER (falces VAL., STEW.; braces AL. AG.). The inter-pyramidal muscles between every two pyramids could not be perceived. The pairs of ex- ternal motor muscles for each of these, the two retractors and the two protractors, inserted upon the two half-pyramids, all arise from the solitary interradial plate, the two protrac- tors, m. pro., very wide apart, the retractors, m. re., very near them. It will be seen further on that during the growth of the test the attachments of these four muscles are removed to paired interradials and finally disposed in another manner.
The fig. 23 is a side view of the dental apparatus in another somewhat more advanced specimen. It is detached from the buccal membrane and from the peristome. The epi- physes, the rotule and the compasses are forming in their places. 'The pyramids are now raised to near their future normal all but erect position, their halves have almost closed at their adoral ends, and there already exhibit some indication of their future shape, but upwards their inner margins, which in the adult will be firmly united by means of a straight and prolonged symphysis, still diverge strongly and leave wide open the foramen magnum Var. Through this opening the tooth is seen, of outward shape as in fig. 22 but leng- thened adorally, and with the lamellar structure distinctly defined. The lamels, the general form of which corresponds with that of the tooth, are laid one upon another regularly, from the top downwards. The fig. 24, from a transverse sec- tion of a decalcified specimen slightly more advanced, shows the lamellar structure which seems to exist alone at this pe- riod.
Thus — assuming it allowable to extend to the whole group the facts elicited from a single species, and that one exceptional in its development, — the Cidarid, on the eve of
entering upon its final mode of existence, enclosed within the pluteal envelope which covers it on all sides, has assumed
! KRoOHN long since described the teeth in a young astomons Echinus. MöLb. Arch. 1891) p. J3L.
10 SVEN LOVÉN, ECHINOLOGICA.
a discoidal form and builds up a new skeleton, of two sy- stems: The calycinal system with the dorso-central disk entire, and the coronal system of two mutually indepen- dent constituents. The five ambulacra, heterotropic from the first, throughout of two columns of plates perforated by pores and bearing pedicels, have their first-formed pairs, the primor- dials, constituting by themselves an innermost closed circle, each pair of which is followed by a consecutive series of succes- sively added plates, the last formed always contiguous to the corresponding radial of the calyx. The five interradia, alterna- ting with the ambulacra, begin outside the primordial circle of these with a solitary plate, which is followed by a double column of successively added plates, the last-formed of which is contiguous to the corresponding costal of the calyx. The animal moves about by the aid of five large and powerful suckers based upon the outer ends of the radials. It takesno food from without, being astomous as well as aproctic, its alimentary canal is funcetionless and it subsists on the stores of cellular matter laid up in its tissues during the previous pluteal freely feeding existence. But within the central part of the envelope it prepares for the imago new feeding-instru- ments, a pharyngeal system of jaws and teeth, and an excre- tory apparatus. While this is doing the disappearance of the provisional suckers, and a line of separation appearing between the primordial ambulacrals and the following pairs, announce the approach of the final state.
It now follows to compare corresponding stages among the families of the Ectobranchiata. The young of these, as far as hitherto described, all derive from free-swimming plutei and belong to the Arbaciide, Echinidre, or Echinometridee.!
To some northern species of the Echinidzee a young spe- cimen 0,6 mm. in diameter seems referable that had been caught by the towing-net in the North Sea and preserved in spirits. Of this specimen figures were drawn by Mr WESTERGREN with the utmost care and not in the least diagrammatic, and published in former works; I repeat four of them in the woodeut an- nexed. They evidently represent the exterior of the Echinid as it is after the last of the calcified rods of the Pluteus has
! See above p. 1.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:O 1. ll
been reabsorbed. Then the period of floating at the surface of the sea is nearly at its end, and the young Echinus is going to sink to the bottom and thus begin its creeping life.
5 il rs Å Å. SR KVA BIS ARSA
(GE
1. Young Echinid, ventral side. 2". Pedicellar pore. 3. Pedicel. 4. Solitary sucker.
Bury has described the same stage in the Echinus parvi- tuberculatus, BLv., and given a figure of its dorsal aspect in the living state.!
The general form is lenticular. Invested all around with the continuous, smooth, pigmented larval covering,? it has no mouth and no exeretory opening, and is without gills. Near the periphery, on the ventral side, the integuments are pro- —! Quarterly Journal of Microscopical Science, New Series. XXIX, p. 440,
PL SKKOOVII feed. >? See Pourtalesia, p. 27, P1. XIX, fig. 232, ventral view, 233 dorsal view.
2 SVEN LOVÉN, ECHINOLOGICA.
duced into five huge, solitary, equidistant, acetabulated, pro- visional suckers, and underneath the base of each of these one pair of much smaller ambulacral pedicels, the primordial, persistent pair, has made its appearance, while on the ventral as well as on the dorsal side of the body the spines have at- tained some length. But no forcipes were seen and I looked in vain for the water-pore which was observed by Bury. With- in the envelope the skeleton of the imago had begun to form.! On the dorsal side, before the specimen was lost by accident, the five costals of the calyx were seen and sketched, five large and thin reticular laminre placed near the periphery interme- diately to the provisional suckers, as shown by Bury. On the ventral side, wood-engraving fig. 1—4, the faithful drawing of the commencing skeleton was finished. The five primordial pairs of ambulacral plates, I, II, III, IV, V, had made their appearance, ten contiguous lamels, each affording a pore for the passage of the ducts of one pedicel. Externally each pair is in close contact with the basis of one of the solitary pro- visional suckers, there being vet no second pair of ambula- crals intervening. Outward, close to the periphery, on the line intermediate between every two pairs, the five primary solitary plates of the interradium are forthcoming. When I first observed them, unacquainted as I then was with the fact of their solitary beginnings, I was much puzzled at being unable to make out more than one single first plate in every interradium. They are, here as in the Cidarid, excluded from the primordial ambulacral circle. But when this will have been followed by a second circle, they will take their places between its five pairs, and then this second cirele, the first peristome, will come to consist of five binary ambulacrals and five solitary interradials, even as in the Cidarid, Pl. IL, fig. 9. This, as has been remarked, is its fundamental con- stitution in the whole class. And outward of this cirele will be added gradually, each plate in close contact with the pre- ceding, of ambulacrals a second circle of five pairs, then a third and so on, every new plate giving passage to the ducts of one pedicel; and while, at the same time, in each interradium the solitary first plate will be followed, not by another solitary one, but by a pair of plates and this by another and so on,
! Etudes s. 1. Echinoidées, p. 27, P1. XVII, fig. 141—152.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0 1. 13
the ecorona will form and in its growth raise up above the ventral region the whole of the calycinal system along with the provisional radial suckers. What precedes has shown that this is the course of the development in the Cidarid; from what follows it will be seen that an analogous process main- tains in the Ectobranchiates.
The fig. 25, 26 on Pl. IV represent the ventral part of a denuded specimen referable, it will seem, to the Strongylo- centrus dröbakensis 0O. F. M. It measures 1,2 mm. in dia- meter and has been cut through horizontally and preserved in Canada balsam. In the centre, fig. 25, is seen the ceso- phagus with its five lobes. "The corona presents in each ambulacrum four pairs and a half of plates. Of these the first-formed, primordial pairs, already separated from those of the second circle, are placed each in front of its fixed am- bulacrum, and still very near it: two expanded oval plates, angularly converging and contiguous near their aboral ends, diverging adorally. They conspicuously exhibit the hetero- tropic disposition, the I a, II a, IIT b, IV a, V b still being without pedicellar pores, while such are present in the I b, II b, III a, IV b, V a.t The second circle, the exactly circular peristome, now consists of the ten paired second ambulacrals and the five well-developed primary interradials, solitary as in the Cidarid, which have entered into the circle and are followed each by a pair of hexagonal, alternating, strong, convex plates.
The stoma is covered, like that of the young Goniocida- ris, by the larval envelope, which is thin and so transparent as not to be made distinguishable in the drawing. The dental apparatus is readily seen through it. Each pyramid has its halves no longer separated, but united together. The tooth is forming, but the keel alone is seen projecting beyond the la- teral parts, which are not yet so far developed.? The sides of the pyramids are not flat, as they will be in the adult, but concave, and hence the inter-pyramidal muscles are very long. The two pairs of external motor muscles are present. The two retractors of each pyramid, m. re., come into view each from under the peristomal margin of a different ambulacrum, at its nearest point, but are wide apart, being separated by
! Compare the Etudes s. 1. Echinoidées, p. 27, P1. XVII, fig. 148. ? Compare JoH. MUELLER, Metamorphose, I, 1848, p. 24, P1. VII, fig. 11.
14 SVEN LOVÉN, ECHINOLOGICA.
the interradium, in such a manner that, for instance, of the two retractors of the pyramid 5 one comes from the plate I a, the other from the V b. Consequently each ambulacrum sup- plies one retractor to each of two different but contiguous pyramids. They are inserted upon the sides of the pyramid on its under, narrowed part. The two protractors, m. pro., are, in this aspect, seen under the retractors, coming into view close together from under the margin of the solitary in- terradial plate, and descend, diverging, towards the sides of the upper, broader part of the pyramid. All this is seen again, under the opposite aspect, when the preparation is tur- ned over, fig. 26. The csophagus is seen in the centre with the folds by which it is suspended. "The rotule are well de- veloped, as are also the compasses, the epiphyses, and all the external muscles, the m. radiales STEWARD, the protractors, m. pro., and the retractors m. re. "The former, m. pro., arise close together on the peristomal margin of the solitary inter- radial, and ascend, diverging, towards the epiphyses on which and on the upper margins of the pyramids they are inserted. The retractors, m. re., of each pyramid arise far apart, each from a point near the outer margin of a different ambulacral plate. At this point of attachment the auricular branch is commencing to form, a low projection of calcified reticular tissue; its basis extends a little beyond the near suture, upon the solitary interradial that separates the two auricles. From these widely distant points of attachment the retractors de- scend slightly converging, as it was seen in the oral aspect, fig:
The calycinal system, fig. 27, occupies a very considerable part of the dorsal aspect. It has still much of its normal condition and is less modified than that which I formerly de- seribed.! The dorso-central disk is entire and well-developed. Opposite the costals 2, 3, 4 it still retains the rectilinear sides of its normal pentagonal figure, and the lozenges of parallel internal rods that cross the straight sutures, are intact. It is otherwise on its line of contact with the costals 1 and 5. There the transformation has already commenced, which is to result in the total conversion of the compact dorso-central piece into the flexible anal membrane.? The lozenges have
! Etudes s. 1. Echinoidées, p. 69, P1. XXI, fig. 171. 2 Ib. fig. 171—176.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:o 1. 15
there disappeared, the substance of the disk is thinning off towards the extended and rounded margin; while a correspon- ding erosion is going on at the margins of the costals 1 and 5. By this process the dorso-central, owing to the growth of the costals 2, 3, 4, and the marginal absorption of the 1 and 5, is moved towards the right side of the animal, all in accordance with what maintains in the whole group of the Echinidze, though scarcely manifest in the Diadematide. Between the dorso- central and these costals 1 and 5, a very narrow clear space is perceived, forming nearly a semicircle, the first indication of the future periproct, but there is no trace in it of an ossicle, as in the former specimen. 'The animal here described is evi- dently younger. It assuredly is not imaginary to assume that, if it had been caught sooner, may be by some few days only, the narrow opening had not existed and the dorso-central os- siele would have presented its primordial, but transitory an- cestral, pentagonal form.
The costal 2, somewhat broader than the others, has still the solitary large water-pore. 'The radials are broad in rela- tion to their length, and slightly concave at the free margin. Over nearly the whole of the calycinal system the epistroma is thinly expanding, more distinetly at the borders, as a glo- meration of minute globules. On the dorso-central, apparently the last formed of the constituents and already on the way to dissolve, it is hardly to be perceived.
Another young specimen, fig. 28, not a little larger, 2,2 mm. in diameter, apparently of the same species as the fore- going, has the mouth free, the teeth naked, the gills formed, and the solitary interradial greatly reduced, but the hetero- tropic absence of the pedicellar pores I a—V bis still obvious in the primordial ambulacrals which keep their places near the future peristome.
This prominent feature in the young animal, the retarded appearance of the other of the two heterotropic series of pri- mary pedicels, the I a—V b, seems however not to be of constant occurrence in the different genera, or perhaps more transient in some forms than in others. It has already been seen that the young Echinus, woodeut p. 11, which has just completed its pluteal stage, and has acquired only one ambu- laeral circle, presents a pore and a pedicel in every one of its plates.
16 SVEN LOVÉN, ECHINOLOGICA.
To the Echinus miliaris LESKE I am inclined to refer the denuded specimen, Pl. V, fig. 29—538, which measures 2,5 mm. in diameter and is far advanced. Its spines were strong, the gills apparently ready for their function. The solitary interradials are all but completely reabsorbed, only a fragment of each remaining. The second peristomal ambula- crals are in part reabsorbed marginally; their ten persistent primordial plates, all poriferous, have their circle removed from the peristome, and the already broad interval is strewn with flakes of calcified tissue, disposed in a certain order. The branches of the auricles, fig. 30, 31, the basal expansions of which are marked off from the plate by a suture, are rising and have begun to diverge and to arch over the ambulacra; and, with all this, the animal so near to having completed its development, is still astomous, its mouth being overlaid with the still persisting larval envelope, fig. 29, 32, more strong and thick than in any of the young already described, and protruding conically over the teeth which push from with- in. The animal is aproctic also, fig. 34. The dorso-central disk of the calycinal system is still entire, but has lost its pentagonal outline and nearly assumed the rounded form of the future anal membrane. It is thin and transparent, and part of its substance is evidently reabsorbed, but there is as vet no trace of its separation into ossicles or of an opening between it and the eroded costals 1, 2 and 5. With this tran- sitory condition and early evanescence the costals and radials strongly contrast. They are clothed with a rich epistrome, clusters and rows of globules from under which spinary tu- bercles are seen emerging, fig. 35—38. Here, as elsewhere, the calyx is the stronghold of the epistrome. It is from this and other particulars that I suppose this young animal to belong to the Echinus miliaris LESKE.
These are details gathered from a few species of Ecto- branchiates in early stages preceded by a prolonged free- swimming pluteal existence. In essential points they agree with corresponding stages of the young Cidarid, even when this is derived from an exceptionally abridged marsupial
! See the author's Etudes s. 1. Echinoidées, p. 67, and the paper on the species described by LINN=Us, p. 86, P1. 7—9. In deseribing there the epi- stroma, I overlooked the notes on it by AL. AGAssiz in Bulletin Mus. comp. Zool. n:o I, October 1869, p. 288.
v
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:o1. 17
development. "There is a resembling discoidal or lenticular form of the body, the same five primordial, locomotive suckers, solitary and provisional. In both, the interior communicates with the surrounding medium through a single large water- pore. In either of them the alimentary canal is closed at both ends, astomous and aproctic; they are endotrophic, take no food from without, and represent in some sort, as has long since been recognized,! a pupal or rather nymphal condition intermediate between the pluteus and the imago. For this their definitive mode of existence they are both preparing by the ultimate formation of a prehensile and masticatory ap- paratus, the completion of which, together with that of the excretory opening, will be the sign of its beginning, and by the building up within the envelope of a new endo-skeleton. Two systems combine in its construction: the calycinal system originating round the dorsal centre, of definite constituents; and the coronal system arising from around the ventral centre, changeable, growing upwards, itself a combination of two heterogeneous sets of plates: the ambulacra, the first to ap- pear, binary from the beginning, heterotropic; and the inter- radia, secondary, perisomatic, commencing singly, then beco- ming binary; both sets tending, by an accordant rate of growth, to raise the test into the globular form.
In all the Echinoidea the growth of the corona is effected by new plates being successively added at the aboral termina- tion of the ambulacra and the interradia, and by their in- creasing in size and solidity. As long as the animal lives, there is at work, more or less, in every part of its frame a conti- nuous movement of reabsorption and renewal, of taking on one form and losing it for another, all in accordance with the morphological canon of the species; and this process is perhaps nowhere more conspicuous than in the corona of the Cidaridee and Echinidee.
When we left the young of the Goniocidaris canaliculata AL. AG., Pl. II, fig. 7—9, which here serves for a type of the Jidaridee, the primordial ambulacral plates of the corona formed by themselves a slightly movable circle round the mouth. A
I GRABER, Die Insekten, II, p. 524—564. — BALFoOoUR, Comparative Em- bryology, I, p. 352 (1880).
2
18 SVEN LOVÉN, ECHINOLOGICA.
solution of continuity intervened between this circle and the next, the plates of which, the second ones and the following, were comprehended in the fixed portion of the corona. The third, fourth and fifth, when completed, were regularly hexa- gonal, and higher than they were broad; the second, the lowest pair, was, as yet alone, somewhat deformed and depressed. It was preparing to separate from the following, to descend and to begin forming the flexible continuation of the corona, the »membrana buccalis.. The columns of the ambulacra will grow rapidly, new plates will form continually at their abo-
Buccal part of an ambulacrum in Cidaris papillata.
ral terminations, and by virtue of the vis a tergo brought on by their augmenting number and enlargement, and the re- sistance afforded by the radial of the calyx, the plates will come to change their places relatively to the interradials, and glide gradually downward between these. towards the stomal region. Whenever, in this manner, one of a pair of plates attains the limit of the fixed part of the corona, the solution of continuity is repeated, the suture which marks its adhesion to the next following plate is seen to open, and the plate to be set free, and to pass, as if discharged through the outlet
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0o1. 19
of a river, into the buccal membrane.! At the same time its form will alter. The arched processes on the inside will spee- dily be reabsorbed, its verruca diminish and disappear; but it will expand strongly in breadth laterally, and in depth, and soon be transformed into a thin scale overlapping the prece- ding one, while its verruca will be replaced by marginal ver- ruculee, and its pedicellar pore sunk into a small and gradu- ally deepening pit. It would be the place here to show how this process goes on from the first, beginning with the remo- delling of the primordial plates into scales, and how it is con- tinued by the descent and transformation of the seconds and so on, but for this specimens are wanting. The nearest ap- proach is offered by a Cidaris papillata DLEsKE, already far advanced, having a diameter of 27 mm. It presents in each ambulacrum, from the mouth to the calyx, on an average, fifty- three pairs of plates, and of these the nine first have become free and movable, in the buccal membrane, and transformed into imbricated scales. Another specimen, of 41 mm., has 69 pairs of plates, of which 13 detached; a third, of 55 mm., has 381 pairs, 15 detached; a fourth, of 62 mm., has 91 pairs, 16 detached, thus:
Diam. 27 mm. 53 pairs. 9I detached
» 41 69 > 18) » ="A"for 16 added =1?: 4 $ FROM KSL yr 415 =O, 12: UETAG 62 JL » 16 > = Id 10 fo
from which it appears that the successive dismemberment of ambulacral plates is performed at a slower rate in the older specimens, and inversely as the rate of addition of new plates at the dorsal termination of the columns. But all the time the buccal membrane, according as it widens, is filled from the fixed ambulacra with the plates next in age, transformed and overlapping and always bearing pores and pedicels. The five pairs arround the lips are the primordial ones and still recognisable as such.
In the interradia the new plates are added at the tops of the columns not simultaneously and equally all around the calyx, but in such a manner that in every interradium one of the two columns precedes the other, and has its last comple- ted plate larger or its new-forming additional one more de- veloped.
! Etudes, p. 28, P1. XX, fig. 166, 167, 168.
20 SVEN LOVÉN, ECHINOLOGICA.
The new plate makes its first appearance in the angle between the costal and the radial, as a minute section of a circle, with the curvature contiguous to the preceding plate. It is developed by little and little of its superficial extent, and, so to say, »alla prima» The adoral margin appears first, and very soon it exhibits a beginning semicircle of verruculze, each of which bears the rudiment of its blade-like spinule. These spinules grow very rapidly and soon lie down converging to protect the central part now coming forth, the cone, which in this stage rises directly from the circumference without any secrobicular depression. In this state the young plate is nearly quadrangular. It now seems to recede from the calyx, acquires its fifth inner angle, the sixth, the external, being adapted to the moving, undulated ambulacrum, obtuse and rounded. Meanwhile the mamelon and spine are forming. Before the last third part of the new plate has appeared they are easily seen developing, as described by PrRouvHo,! if the co- vering spinule are drawn aside. Each of these begins as a low, circular elevation. A series of sections shows that the mamelon, rising from the cone, and flat at the top, is covered with a low and thin cap, the first rudiment of the spine. When nearly the whole of the plate has been formed and the mamelon is almost central and fully encireled by the multi- plied spinulze, the cap has grown convex and its underside concave, fitting to the mamelon, and in either there is a cen- tral pit for the inter-articular ligament. Then the cap thick- ens and becomes higher, while the flanks of the cone become slightly concave, an impression all around renders it exter- nally distinct from the mamelon which takes a semiglobular form, and the rudimental spine, now twice as high and tape- ring upwards, bulges out below to form the head and ring, and the shaft soon shoots up and increases forcibly. In a specimen 50 mm. in diameter the weights, in grams, of the five uppermost plates and their spines are respectively and relatively:
a 8 Plate, Gram 0,0425: Spine, Gram 0,0001 = 1; 0,0024
6 IR ÖT 0,0049 = 1:0,0382 3 ar » 0,2095: » 0,6291 = 1: 3,0n29 brönne >» + 0;2350: > > 10,94238=1:4,01
GLÖD 0,2510: ] 1,2640— 1: 5,0358.
! Recherches s. la Dorocidaris papillata, p. 46.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:o1. 21
And when the weight of the plate and that of the spine a 8 are severally assumed as 1, the rate of growth is:
ÖS ORK RNA b 6 a 6 IPläte: NA rJ:0G- 4,93. D,53. D.9: Spine: 1. ' 49. 5291. 9423. 12640.
It is seen that the increase is immensely in favour of the spines.
While the dorsal and middle part of the coronal interra- dium is the seat of this vigorous growth, the reverse is the case in its ventral region. In any adult specimen of Cidaris it is readily seen that the scrobicules of the interradial corona, dorsally all but circular, downwards become more and more oval transversely, while their rings of verruculze, which at first keep distinet above and below, are seen to approximate, then lower down to intermingle, to become defective, and at last to vanish, the secrobicules nearest to the peristome run- ning into one another. "This is the effect of the pressure from above combined with the loss of substance gomg on in the ventral parts. The plates near the stoma are seen to dimi- nish; little by little their superficial extent consumes from reabsorption, they are cut right off adorally by concentric abrasion and what remains melts away. In part their calca- reous substance consolidates again in the buccal membrane and reappears there as single or double scales, minute, thin and fat, slightly imbricated, without even a trace of a verruca, but bearing a row of verrucule at their straight adoral margin. This process is analogous to that observed in the ambulacra, but here it takes place less regularly and more sparingly and begins somewhat later; the adoral end of each triangular set remains behind that of the ambulacrals. The huge pri- mary, mesial and solitary plate of the interradium in Gonio- cidaris, fig. 9, is the first to be reabsorbed and remodelled, and after it come successively the following binary plates. If now these same parts are examined in a specimen of Ci- daris papillata 42 mm. in diameter! this buccal series consists of six plates, all simple or nearly so. In a young Cidaris Thouarsi AG., of 11 mm., three minute interradial plates are found in the buccal membrane, the first single, the second mostly also single and entire, but in one or two of the inter- radia divided into a pair, the third everywhere single and
' See the woodeut on next page.
22 SVEN LOVÉN, ECHINOLOGICA.
entire, and in one or two cases a fourth very minute single and mesial plate becomes visible from under the limiting plate of the corona. Thus, while the corona increases in circumfe- rence and the buccal membrane expands, the interradial plates at its adoral termination, like the ambulacrals, are subject to gradual reabsorption and transformation.
Buccal interradium of Cidaris papillata.
When this process is followed through successive stages of growth, there are found in the Cidaris Thouarsi AG.
Diam. 11 mm. Coronal pairs 5 and 6 — detached 3 and 4
ERE AES i » 5 and 6 — 4
3, Ad e » 6 and 7 — 4 20..1E 6 and 7 — 4 and 5
22 id -—- 1
in the Cidaris papillata LESKE.
Diam. 27 mm. Coronal pairs 6 and 7 — detached 4 and 5
46 "> ” Tand 8 — » 6 55 s 408 — 2 and 6 62 ; RN = 6 and 7
and it becomes evident that the ventral interradial plates are detached and transformed rather irregularly and at a rate slower than that of the dorsal increase. They are given off one after another, and form together a triangle filling a small space left between the expanded buccal ambulacra; in their smallness and tenuity they strongly contrast with the broad and solid still fixed coronal plates, from which they are deri- ved, and the rate of their formation appears not to correspond
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:o1l. 23
with that of the consumption of these, at least if it be as- sumed that the scale at the adoral top of the triangle, the first detached, represents the solitary primary interradial of the corona.
The one of the binary columns of each interradium which thus loses a peristomal plate, is that which about the same time receives the increase of a new dorsal plate. Generally also the columns corresponding in order all around are at the same stage of growth. Thus, if in the a columns of all the five interradia the new top-plate is more advanced than in the b columns, the loss of substance at their adoral terminations is also grea- ter; and, vice versa, if the b column exceeds at the top, it loses inferiorly. From this rule, however, I found a few ex- ceptions, and there may possibly exist some interchange in this respect. Upon the whole, here as well as in the ambu- laera, since the number of plates in each column augments, and their bulk goes on inereasing, the dorsal growth of the test must exceed the rate of reduction below.
The reabsorption thus described as seen in the outward aspect, is accompanied on the internal surface of the same plates by a simultaneous process of another character, but of a similar final effect.
When in a Cidaris papillata the peristomal circle is viewed from the interior of the test,!' it is readily seen that the three consecutive pairs of plates which for the time being to- gether constitute the adoral limit of the coronal interradium, compared with the following plates are in a state of transfor- mation. While they become depressed longitudinally they grow high upwards at their adoral margins, the third plate c, in a slight degree, the second, b, much more, and the first, a, which at the time begins the column adorally, to such an extent as to form a high and broad projection affording ample attachment to the whole of the external muscles of the corres- ponding dental pyramid. In the astomous stage of the Goniocid- aris, Pl. III, fig. 22, m. pro, m. re, both pairs of these muscles were attached to the solitary primary interradial, near its adoral margin. Itis evident that when this plate was being reabsorbed, they must have been received by the following binary plates which afforded extended attachment on their growing projections, and that, when these were melting away, they were transferred
! See woodeut on next page.
24 SVEN LOVÉN, ECHINOLOGICA.
to the next, and so on. For, as soon almost as a projection has attained its full size, it is subjected to the reduction so manifest externally. It is gradually thinned off by reabsorp- tion, now more in its upper part, fig. 3, now more in the lower, fig, 4, and loses its verruca. And while the projection on which the muscle is attached thus gives way, the next plate rises and takes its place, to be backed in its turn by the third, and so forth. In this manner the movement goes on that maintains in full strength the supports of the masti- catory muscles.
U
Auricle of Cidaris papillata LEsKE. 1. Adoral side. 2. Aboral side. 3—5. Sections.
These supports, divergent projections developed from the interradia as successively renewed continuations of their sub- stance, are functionally analogous to the auricles of the Ecto- branchiates, but morphologically very different. Still it will be convenient to let them bear the name of auricles.
In the great division of the Ectobranchiates the mode of growth of the corona is essentially; the same as in the Cida- ride. The new plates are added at the dorsal margin of the last-formed ones, there is an incessant downward movement, and a continnual disintegration at the margin of the peristome. Like the Goniocidaris the still astomous Echinid has the pri-
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0O1. 25
mordial persistent plates of its ambulacra arranged in a conti- nuous circle round the future mouth, Pl. IV, fig. 25, 20. But, whereas in the Cidarid each of them becomes overlapped by one of the second circle transformed into a scale, and this si- milarly by a third and so on, and a fexible succession of pe- dicel-bearing scaly ambulacrals thus is effected from the mouth upwards, we have seen that in the Echinid, already before the close of the astomous stage, the primordial circle has con- tracted relatively to the circumference of the peristome, Pl. V, fig. 29, and that there has intervened between them a cir- cular belt of flexible membrane, in which are contained as- semblages of calcified corpuscles of irregular form, destitute of vedicels. The original sequence of pedicelligerous plates is thus broken between the fixed ambulacrals and the primordial. This interruption is due, not only to the progressive widening during growth, but, also, and perhaps chiefly, to the reabsorp- tion of calecareous tissue which from an early period is at work at the adoral margin of the fixed corona. It has been seen that while the primordial pairs of ambulacral plates remain persistent through life, the second pairs, together with the so- litary primordial interradials, are very soon worn away, Pl. PPG 526, 2810 Pl VII fig 29, 30) not in a manner con- sistent with the immanent mode of formation of each plate, but as if through an agency from without, emanating from the oral centrum, and affecting little by little the whole of their several adoral margins with a uniformity all around which in this group becomes most obviously manifest in the strict circularity of the peristome. In the Strongylocentrus dröbakensis O. F. M.! this abrasion goes on in such a manner that the pedicellar pore marked 2 which in a specimen of 3 mm.? has its place near the lateral middle of its plate, in a specimen of 6 mm., and in others a little older, is found close by the adoral margin and there partly absorbed, and that it soon is followed by the pore marked 3; that the spherid and the verruca, which in the 3 mm. specimen? are the first in III a, are lost in the 6 mm. specimen, as is also the second spherid, III b, in the specimen of 15 mm? It is thus seen See Etudes s. 1. Echinoidées, p: 20, 24, 37, P1. XVII, fig. 140—147.
1. ec. fig. 141—2144.
1. c. fig..140, 141.
1. Ib
ce. fig. 14. ce. fig. 146.
Öm BB VO ww
260 SVEN LOVÉN, ECHINOLOGICA.
that the reabsorption is continued at a gradually reduced rate, and in the adult probably attains a minimum.
The buccal membrane devoid of pedicels is of all but uni- versal occurrence among the Ectobranchiata when adult, and almost characteristical of their group. One family alone makes an exception, that of the Echinothuride. These exhibit a struc- ture of the buccal membrane comparable in a certain degree to that which characterizes the Cidaride. I venture to take the Asthenosoma varium of GRUBE as an example. Pl. XII, fig. 161, gives the outside view of the peristomal region, drawn from a photograph. The woodeut p. 27 fig. 1 represents the peristome seen from the inside, the auricles being omitted, while fig. 2—6 give the same parts of the five ambulacra seen from the outside, the plates marked with corresponding numbers.
In this genus the ambulacra are much broader in propor- tion than in the Diadematidee, at the ambitus half as broad as the interradia, and gradually contract, not expand, towards the peristome, having there about 0,80 the breadth of the latter. Their plates are compound, numerous, and low. They are triads consisting of one entire, aboral, plate and two adoral demi-plates. The entire plates are imbricated down- ward, adorally, by means of an inner rounded lamellar lobe, shaded in the woodecut fig. 2—5, emitted aborally near the mesial, sutural end, and overlapped by the following plate; laterally they have shorter lobes overlapped by the interra- dium. "The demi-plates are minute, contiguous, received into an emargination of the entire plate; near the calyx and ven- trally they are broad, somewhat rhomboidal, and placed dia- gonally, towards the peristome more triangular; dorsally on the flanks lanceolate, and placed almost in a transverse line, the middle one rather elongated, the inner one submesial. They have, there, no lamellar lobes or very slight ones. The pores are disposed into ascending rows of three, arched on the ventral side, nearly straight and transverse dorsally. The outer pore in every row, the first one from below, is that of the entire plate; the other two belong to the demi-plates of the next triad. If the plates of any such row of three pores are numbered 1, 2, 3, the 1 being the entire plate, the 2 and 3 the demi-plates of the preceding compound plate, the fixed ambulacral columns I a, IL a, IIT bb, IV a; Vb; are found, in the specimen figured, to terminate at the peristome with
DO -1
BIHANG TILL K: SV. VET.-AKAD.: HANDL. BAND 18. AFD. IV. N:01.
Asthenosoma varium GruBE. Fig. 1. The five peristomal ambulacra, from the inside. Fig. 2—6, the same plates detached, from the outside.
bo
28 SVEN LOVÉN, ECHINOLOGICA.
an 1, that is with an entire plate, in a state of disintegration and transformation, whereas the columns I b, IT b, TIIT a, TV b, V a each of them end with a 3, that is with the innermost demi-plate of the preceding plate, but more or less augmented and transformed. It is so that at this point a new order sets in. The plates are one by one detached, and gradually trans- formed into scales as in the Cidaris, but in a thoroughly dif- ferent manner. In the Cidaris the auricles arise from the in- terradia and consequently the passage downwards of the am- bulacral plates which are all similar, entire and simple, is free, and the mode of transformation the same for them all, every one in its turn being operated upon like the others, precedent and following. In the Asthenosoma on the contrary, not only it belongs to the plates which at the time are peristomal to support the auricles, but the plates being unequal, every two minute demi-plates are followed by one large entire plate. This subordi- nation of the two plates of the triad is undone in the act of separation and transformation, and every successive plate, en- tire or demi-plate, large or small, invariably and irrespecti- vely of its precedent condition, is brought into the shape and size which conforms to the place it will have to fill in one of the five triangular buccal areas. At the same time, the steady support of the auricles must be maintained. To this end, during the whole of the process, the sutures between the plates become closer, the connecting fibrous tissues stronger than they were higher up, and the firmness of the whole structure is kept up by the moving plates. In the I a, II a, ITT b, IV a, V b, the entire plate IT, which is foremost in the fixed peristome, in parting from it, glides with its external lobe under the base of the auricle, and supports more than the half of its base, the rest being sustained by a now pro- duced lobe of the following demi-plate 2. The entire plate I loses in circumference, and the part of it that bears the pore, in size like one of the demi-plates, separates from it, leaving an indentation. At the same time, in the other column, the corresponding demi-plate 3, which is foremost in the I b, II h, IIT a, IV b, V ua, in approaching the peristome receives on either side an inner, or sometimes even outwardly visible, la- mellar lobe (see woodcut fig. 2—5) transverse and rectangular, that expands externally beneath the base of the auricular branch, and supports it in common with the following entire
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:01. 29
plate. From this lobe it will separate and in its turn descend alone into the buccal membrane. Thus, at this stage, all the ten parting plates — their lobes apparently being left and reabsorbed, — are demi-plates. As such they begin to form into. scales. Of these the five buccal columns I a, II a, III b, IV a, V b, Pl. XII, fig. 161, contain each seven fully de- veloped scales, of which the last, the seventh, is a transformed demi-plate 3, and this is followed by the detached poral part of one of the five entire plates in the act of parting. The colmmnst., Oo. b,-IEN0 IV br Va, on the. other, hand, con- tain each eight scales, of which the last-formed, the eighth, derived from a transformed demi-plate 2, is unequally deve- loped, not far from fully so in III a, V a, II b, less so in I b and IV b. They all soon conform to the new order and become regular constituents of the flexible buccal membrane, taking the shape of adorally overlapping scales. Every one of these is of an angular form, the inner branch being the shorter. Their aboral, narrow, raised margin bears a row of verrucule, while the adoral submerged part is produced into a poimted lamina, fig. 161, projecting aborally beneath the following scale. 'Ihe five triangular sets, each consisting of two ambulacral columns, occupy the whole of the buccal mem- brane and are contiguous to one another, their boundary lines commciding with the mesial sutures of the interradia.
It is readily seen that in all this the heterotropy is strictly maintained. It pervades the whole of the ambulacrum.
The dorsal pores, Pl. XII, fig. 165, 166, have the peri- podium only little marked. ”'The perforations are nearly equal, approximated, the inner one separated adorally by a very thin partition from the meatus of the ambulacral nerve; the bridge is narrow. Dorsally and at the ambitus their position is trans- verse, ventrally and towards the peristome more and more diagonal, fig. 164. When being detached into the buccal membrane they become almost longitudinal, fig. 162, 1653, and unequal, the aboral one diminishing, while at the same time the peripodium becomes more marked, contracted, rounded, and deeper.
Thus the ambulacral system of the Asthenosoma, taken as a whole, is thoroughly different from that of any other of the Ectobranchiates, in the constitution of its compound plates and the arched rows of the pores, as in the existence of de-
30 SVEN LOVÉN, ECHINOLOGICA.
tached buccal sets. As long as contained in the fixed part of the corona the ambulacrum is as different as possible also from that of the Cidaridze, characterized by their narrow series of similar simple, entire, primary plates. But as soon as set free in the buccal membrane, the ambulacrum of Asthenosoma as- sumes, in its own way, the Cidaridean mode of conformation and has its plates one by one remodelled after a similar type, every plate retaining the pore and the pedicel.
The plates of the interradia are not greatly different in outward form from those of the ambulacra. They are nume- rous, low and broad, each of their columns at the ambitus nearly equalling in breadth the two of the ambulacra. On the dorsal side they feebly bend adorally in the middle. But they imbricate throughout in the opposite direction, aborally, towards the calyx, fig. 161, and emit downward, adorally, at the mesial suture, an internal thin lamellar lobe projecting under the preceding plate. HLaterally they overlap the ambulacra. On the dorsal side they are lower, feebly contracted at the middle, and imbricate near the mesial suture as well as laterally. They are totally excluded from the buccal membrane, being abraded adorally, and in the narrow naked interstice that thus arises between their margins and the aboral borders of every two ambulacral areas, are seen, besides the gills, a few minute ir- regular spicules.
A structure like this of the ambulacral and interradial systems in the genera Asthenosoma and Phormosoma is not one of late origin. It existed in the Echinothurize of the Chalk and was fully developed in the genus Pelanechinus of the Oolite carefully studied by KEEPING! and GrRooM.? There is the same disposition of the ambulacra which at the ambitus are fully half as broad as the interradium and gradually contract towards the peristome, each compound plate consisting of one aboral entire plate and two adoral minute demi-plates, which three together externally give rise to ascending rows adorally begun by the pore of the entire plate. The imbricated scales of the buccal membrane are strikingly similar; they are all ambulacral, to the exclusion of the interradials. 'The spinary system also is the same, and there can be no doubt that this
' Quarterly Journal Geol. Society, n:o 136, XXIV, p. 924, P1. XXXIV, 1875. KG BD RA oe TRA SG I DB Ro VA DT SN
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0o1. 31
earlier, in palzeeozoic time, certain genera of the Perischoechinoi- dea, such as Melonites or Lepidestes, exhibited a structure of the ambulacra in which we perhaps ought to see a prece- dent of that now obtaining in the Echinothuridee, and which highly deserves a closer study: a submesial large plate and a rather irregular series of numerous smaller plates. On the other hand, the opposite imbrication of the two coronal syv- stems has descended also to the genus Astropyga and others among the Diadematid:e, and survives in the recent Spatan- gide, of which the heteropodous ambulacra, the position of the spheridia, the perforated mamelons, the petals, and the variform spines suggest a distant affinity to that group, a fact of which LINNAZUS already had a presentiment.!
In the great majority of the Ectobranchiates the disintegra- tion of the peristome is, as we have seen, much more efficient than in the Cidaride and the Echinothuridee, the membrane being left almost naked, and when the calcareous substance is redeposited there, it is under the form of corpuscles much reduced in size, irregular in shape, and devoid of pores and pedicels, Pl. XII fig. 153—160. "These corpuscles may be dis- tinguished as of two kinds: spicules more or less submerged in the thickness of the buccal membrane, and others, lamellar flakes rising wholly or in part above its surface and armed with spinules and forcipes.. Different in shape as all these are from any other coronal element, their mode of distribution betrays their derivation. In front of every fixed ambulacrum they mark out more or less distinctly an area representing the site of its dissolved plates, the wrecks, as it were, showing the way of the retreating peristome. "Their adoral ends ad- join the pair of persisting primary plates. Other areas are seen in front of the interradia exhibiting other marks; but the ambulacral areas are more conspicuous and more advanced.
The affinities of the recent Diadematida to the Astheno- soma are distant enough, less so, however, than those of anv other group. Accordingly the arrangement of spicules and lamingee in their buccal membrane may be expected to have some closer resemblance to that of the Asthenosoma than that of any other form. So it is in reality. In the Diadema saxa- tile L.,> Pl. XII, fig. 153, every primordial pair of ambula-
! See my paper on the Echinoids described by LiSN2aus p. 131. step
2 SVEN LOVÉN, ECHINOLOGICA.
crals is connected with the fixed peristome by means of a tri- angular area with the two equal sides arched, marked out by numerous sunken spicules, large, fusiform or lanceolate, trans- verse, imbricated adorally, arranged in two columns, mostly smooth, while a limited number of them partly rise above the membrane and thus form transverse ridges studded with ver- rucules, spinules and forcipes, and disposed so as to represent the outlines of the area, in two marginal series, one mesial, and two, less complete, intermediary. The narrow space be- tween every two areas is interradial; its crowded spicules are very minute near the peristome, then slightly increase, again diminish, and between the primordial pairs pass into the strong raised scales that fringe the buccal lips. The same disposition obtains in the Echinothrix Diadema L.!, and is but slightly different in the Astropyga pulvinata LAmMcK in which it was already seen by AL. AGaAssiz? In the Centrostepha- nus coronatus ÅL. AG., Pl. XII, fig. 154, the thin and trans- parent buccal membrane is without any minute spicules, but presents in the ambulacral areas large, linear, transverse la- mels, mostly sunk and smooth, arranged to a certain order. At the peristome there are on each side one large lamel, rai- sed, tuberculated, emarginate for the gills; in the middle a succession of narrow lamels, parallel, transverse, beginning aborally with a mesial short one, followed by a roughly tri- angular set of gradually longer and more crowded imbricated ones, out of which one or two in the middle and one on each side near the primordial rise above the membrane and are verruculated.
The Aspidodiadema Antillarum AL. AG., Pl. XII, fig. 155, as already remarked by AL. AGaAssIz?, is highly exceptional. Adult specimens with large sexual apertures recall the post- pluteal Cidaris, Pl. II, fig. 9. The ten paired primordials occupy nearly alone the entire buccal membrane, they are large and slightly wedge-shaped, heterotropic in size and imbrication, and separated from the peristome by a very narrow interstice, in which there are seen some few minute lamels. Thus in this one genus of the Diadematidse the juvenile character of having the calcified corona continuous from the mouth to the calyx by
FA RR a > Blake Echinoidea p. 33. 2 TA FH: apor ee PL Oe
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 1S. AFD. IV. N:01. 33 means of an uninterrupted sequence of pedicelligerous ambula- cral plates, persists, seemingly at least, in the adult, while in the other genera of the group the traces left by reabsorbed ambulacrals in the large circular belt between the primordials and the peristome, are plainly recognized under the form of five ambulacral areas. The interradials are much less distinct. Among the other Ectobranchiates, while anything closely re- sembling the disposition in the Diadematide is hardly ever met with, the calcified particles of the buccal membrane are, however, generally more or less plainly distributed, numerously into five ambulacral groups, and sparingly into five interra- dial. In the Echinus esculentus L. Pl. XII, fig. 156, the caleified particles are of two sorts: minute, almondshaped, transverse, glossy, submerged in the membrane, and others raised above it, fewer, larger, convex, ovoid, verruculated, as- sembled in groups, in front of the gills and thence to the outer sides of the primaries, and in the middle. In front of the interradia there are none, or very few and minute particles. In the Echinus angulosus LEsKE the submerged particles are numerous, very minute, the raised ones fewer, larger, roundish, forming two groups in front of each ambulacrum, between the peristome and the primordials. The narrow interradial areas have only very minute corpuscles. — The Echinometra Matheei Biv., Fig. 157, has the submerged spicules very minute and slender, somewhat larger and densely crowded along the middle of each ambulacral area; the raised corpuscles small, ovoid, sparse, but forming two somewhat marked groups from the gills to near the primaries; the submerged spicules of the in- terradia are very minute. — In the Tripneustes Gratilla L. there are no submerged corpuscles and the raised ones are sparse, minute, rounded, clustered at the gills and about the middle of the area, and a few larger, flattened, between the primordial pairs. — The Lytechinus semituberculatus VAL., Fig. 158 has the entire membrane densely covered with flat- tened, mostly rhomboidal, plate-like, centrally verruculated lamine, larger in front of the ambulacra, from the gills to outside each primary pair, smaller and less erowded in the triangular interradial area, minute near the peristome. — In the Echinocidaris nigra MoLr., Fig. 159, it is hardly possible to make out any order among the thickly strewed, raised, mi- nute corpuscles, each with the large conical verruca for a for-
3 (SÅ
34 SVEN LOVÉN ECHINOLOGICA
ceps. There seems to exist some linear arrangement leading towards a group of larger verruculated lamels near the pri- mary pair. — The Salenia Pattersoni AL. AG., fig. 160, pre- sents a peculiar disposition.! The primary ambulacrals are very large and have their pores near the aboral margin. Between them and the peristome there is a succession of large imbricated scales arranged in three series, one mesial and two lateral, while the interradial areas are covered by a series of their own, of smaller scales. l
It is not here the place to enter into further details re- garding the form and distribution of these minute particles, derived, for a great part at least, from the disintegration of the first peristome.
In the whole class of the Echimoidea it is the rule that the ambulacra constitute a double column of paired plates con- tinuous from the lips to the radials of the calyx. So it is in the Spatangidee,? so in the Echinoneus.? In the Cassidulidee? the primordial ambulacrals are very large. In the Clypea- strida) they were recognized already by JOHANNES MÖLLER,” conspicuous as they are from the size of their pores and pe- dicels.
Likewise it is a rule that the columns of the Hibera begin ventrally each with a solitary plate. This is univer- sally so in the Spatangide, the Cassidulideée and the Clypeas- tride; the Echinoneus, notwithstanding the distortion of its peristome, preserves the solitary plate entire, or nearly so, in the interradia 2, 3, 5. In all these groups it forms part, un the adult, of the first circle.
The Ectobranchiates, including the Echinoconidee, and the Cidaridee, do not fail strictly to obey both these rules. At an early period of their nymphal life each primordial pair of the ambulacra is closely followed by its two columns, and the in- terradia begin each with a perfect solitary plate, Pl. IT, fig. 9, Pl. IV, fig. '25... But at the same time as the skeleton is being built up thus in accordance with the general rule, an-
! ÅL. AGAssizZ, Blake Echinoidea, Py 14 CPL TYS IiS AT IO ? Etudes, P1. XXIIN—-XLII.
34 1b- PLATA.
Cs ME MÖRE SON
3 Ib., P1. XLIV—LII.
5 Ueber den Bau der Echinodermen, p. 39.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND1S. AFD. IV. N:01. 35
other operation has supervened, the retarded final one of den- tition, of breeding teeth and jaws. These massive parts in the act of forming require an abundant supply of organized caleareous substance, and in the future imago they will de- mand, powerful instruments as they are of prehension and di- minution, the greatest possible facility of motion. For their sake, it will seem to me, in order to prepare for them pliant surroundings, the currents of development are at last turned, and caleareous matter just deposited in duly formed skeletal constituents, is reabsorbed: remodelling in the Cidaride and the Echinothuride, all but dissolving in the other groups. This is the origin and history of the buccal membrane.
The extension to which the oral region of the corona in consequence of growth and disintegration thus is made flexible and the stoma widened, is different in the various groups. If the external diameter of the corona, measured in the direction of III—5, is taken as 1, the corresponding diameter of the stoma is as follows:
In Cidaris papillata LESKE 0,33;
in Asthenosoma varium GRUBE 0,30;
in Arbacia punctulata LMcK. 0,59, Å. australis TRoscH. 0,52, ÅA. equituberculata Bry. 0,51, Coelopleurus Maillardi MICH. 0,47;
in Echinometra Lucunter L. 0,55, Heterocentrus mamil- latus L. 0,54, Echinometra oblonga BLv. 0,39, Stomopneustes variolaris LMcK. 0,25;
in Diadema saxatile L. 0,45, Echinothrix Diadema L. 0,38;
in Strongylocentrus granularis SAY 0,34;
in Spherechinus granularis LMcK 0,32;
in Boletia Pileolus LMcK 0,34, Tripneustes Gratilla L. 0,28, 'T. esculentus LEsKE 0,23;
im Echinus esculentus L. 0,29, E. melo LMCK 0,24;
in Amblypneustes pallidus LmMcK 0,28, Salmacis sulcata AGASS. 0,25, S. bicolor AGaAss. 0,22.
It is seen that the diameter of the stoma varies greatly in its proportion to that of the test, between 0,59 in Arbacia and 0,23 in Salmacis.
While in this manner a loss of calcareous substance goes on ventrally, the number of coronal plates is augmented dor-
36 SVEN LOVÉN, ECHINOLOGICA.
sally, and while the whole of them is slowly pressing down- ward in the direction of the stoma, the new ambulacral plates are transformed, if not in all the Ectobranchiates, at least in their greatest majority, from being primitively simple and en- tire into secondary compound plates, consisting of entire and demi-plates in regular succession, and finally coalesce near the peristome! in such a manner that the adoral termination of the column instead of being, as in the Cidaride and Echino- thuridee, in a state of continual pliancy constantly renewed, becomes a solid barrier against the flexible buccal membrane. The inner surface of the peristome thus consolidated is in the Ectobranchiates the site of the auricles.
It was BLAINVILLE? who in 1825 first drew attention to these projections as they exist in genus Echinus of LAMARCK. The appellation auriculze, evidently suggested by the form of their arched pairs of branches often recalling that of the ears of a vessel, has been universally adopted and possesses every claim to be kept up.
The early appearance of these parts, in the astomous stage, has been described above pag. 14, 16. On every ambulacrum the two branches of an auriele are commencing to form, Pl. IV, fig. 26, each of them at first a slight deposit of calcified re- ticular tissue, a low projection differing in aspect from that of the plate from which it rises, extending a little beyond the near suture, upon the solitary interradial adjoiming. At a later stage of the astomous period, they are seen to rise, to begin to diverge and to arch over the ambulacrum, and their basilar expansions are marked from the plate by a distinct SUtuTÖ BENNO NIL
When the skeleton of an adult specimen of an Ectobran- chiate is broken to pieces, the auricles are found invariably to adhere to the ambulacra and to separate from the inter- radia. The nature of their connection with the ambulacra is revealed by that same suture,? more or less distinct, but with some care observable in any species. The woodecuts annexed represent its position on the peristome of two types of this division which in other respects are widely different, the Dia- dema saxatile L., and the Tripneustes esculentus LESKE, of the
! Etudes s. 1. Echinoidées, p. 20, P1. XVII. ? Dictionnaire des Sciences naturelles, XXXVII, p. 62, 79. 3 Etudes, p. 19, 28.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:OI. 37 group consisting, besides, of the genera Boletia AG. and Lyte- chinus LÖUTKEN.
In the Diadema saxatile L., when an auricular arch is viewed half sidewise from behind, that is from the cavity of the test: fig. 1; from before, that is from the stoma: fig. 2; or from behind: fig. 3; or sidewise: fig. 4; the suture «a, b, c, marks the extent of the adhesion of the basilar expansion of the au- ricle to the ambulaecrum. From a to «' and from a to b it denotes the continuation of the main suture between the am-
Auricle of Diadema saxatile L.
bulaerum and the interradium, which diverge at b, so as to form each of them one side of the branchial incisure. In the four figures the suture a, b, c may be followed all around, on the ambulacrum. In fig. 7 it presents between a and c a very irregular, projecting and receding course, the thinned edges of the expansion of the auricle being conspicuously lacerated. This is because in this genus there are found here and there on the inner surface of the ambulacral plates isolated, more or less pointed knobs, analogous, perhaps, to the arcuated projec-
25 SVEN LOVÉN, ECHINOLOGICA.
tions in Cidaris. 'The basilar expansion is seen to.bend round them, and hence the suture takes a fexuous course, not the same in different specimens.
In the Tripneustes esculentus LEsKE, when an auricle is viewed sidewise from the interradium, fig. 1; from before, that is from the stoma: fig. 2; and from behind, that is from the cavity of the test: fig. 3; or the base of the auricle and the ambulacrum in separation: fig. 4, the suture a to ce marks the extent of the adhesion of the auricular expansion to the am- bulacrum. From a to a' and from a' to b it is the continua- tion of the main suture between the ambulacrum and the in- terradium, and the triangular space included between «a, a', and b, fig. 1 and 4, is the even surface of contiguity between them, the auricle projecting into a heel meeting the ridge of the interradium. At b they separate, to form, each by itself, one side of. the branchial incisure. Hr0Om 0,0/tg-sI fo Sm the course of the suture is on the ambulacrum, traversing its plates, and entering their interstices, and then it bends inwards, c, crosses the plates and reaches at a the main suture again. The ambulaecral vessel and nerve on their way from the peri- stome take their course over the expansion which receives their branches and becomes penetrated by perforations conti- nuous with the pedicellar pores beneath, fig. 2, 3, 4. Al this is readily seen when the auricle is carefully loosened from the ambulacrum, fig. 4, and its mode of fixation brought into view. The ambulacral plates, the impressions of which are seen on the underside of its basilar expansion, are raised so as to form a diagonal crest and on the outer side of this a triangular depression, in which, as in a shallow socket, the auricle is lodged with the part a, c, b. The surface a, a', b of the heel is in contact with the interradial ridge. 'The whole constitutes a fixed articulation, no doubt with a soft substance intervening, admitting of no appreciable movement, »squamose» towards the ambulacrum, »harmonice» towards the interradium. Whereas the auricles of the Cidaris were seen to arise solely from the interradia as contimuations of their tissues, and while beimg reabsorbed below to be reconstrued from above, the auricles of the Ectobranchiates are seen to adhere to the ambulacra as distinet and independent parts joined mainly to them by means of articulation, and to increase by their own growth. both surfaces, the auricular and the ambulacral, during the
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18, AFD. IV. N:O I. 39
Auricle of Tripneustes esculentus LESKE.
40 SVEN LOVÉN, ECHINOLOGICA.
constant fluctuations of absorption and renewal mutually main- taining their firm connection, the auricles insensibly gliding aborally, while the ambulacral margin retreats, thus holding their positions as supports of the maxillary system. It was from earlier observations on this subject that I formerly was led to conceive the auricles as belonging morphologically to the dental system.! The phases of their evolution here described, though not altogether inconsistent with this supposition, can- not be held as sufficient evidence in its favour. When the structure and evolution of all these parts shall be better known than they are at present, this question, with many others, will arrive at its decision.
Dissimilar as are the Ectobranchiates with respect to these parts, they come near to the Cidaridee in the structure of the imterradia. The peristomal plates of these grow upward into internal processes, which thicken and form a wall or a strong ridge towards the buccal membrane.
The structure of the dental apparatus in the Regularia has long been known in its principal points, thanks to many able investigators, among which VALENTIN? and T. H. STEW- ART? stand foremost, while the histology of the teeth has been carefully studied by GIESBRECHT.? In each of the five equal and uniform pyramids (woodeuts p. 53, fig. 1—4) the two la- teral surfaces, b, are flat and densely marked with transverse, fine, feebly undulated, parallel ridges for the attachment of the inter-pyramidal muscles. The wings converge inwards, but leave an open space between their pectinated cesophageal mar- gins. The third, external, triangular surface, a, areuated, convex and smooth, emarginated in its upper part by the »foramen magnum» of VALENTIN, presents outwardly, within its narrow lateral margins two longitudinal depressions, and a mesial elevation which expands adorally and forms alone the whole of the adoral termination, taking there, the shape of a spoon with a small notch at the tip, the processus labialis. ÅA me- sial suture, always present, marks the symphysis of the two
Etudes; Pp: 19, 28,31:
AGAsSsIzZ, Monographies d'Echinodermes I.
Proc. Zoological Society, 1861, p. 58, Pl. X, XI. Morphologisches Jahrbuch VI.
BB VS NN -
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0o1. 41
half-pyramids which are held together by an intervening fibrous tissue, Pl. X, fig. 129. Seen from within, c, each half presents its somewhat triangular wing, ala, slightly concave, thin at the csophageal, nearly straight, margin and transversely truncated superiorly; and externally, a massive arcuated wall, upwards continued in a process that rises above the wing, the processus supra-alveolaris, various in form but generally three- sided and more or less pointed. It is to the lateral surface of this process that the main body of the epiphysis is ap- plied, while its basal prolongations rest on the transverse ledge formed by the truncated and groved thickness of the wing. Within the alveolar cavity, enelosed between the two wings and the outer wall, the tooth, enveloped in its matrix, is placed on its slide, in the mesial groove, the »sulcus dentalis» VALEN- TIN, which is equally divided between both half-pyramids, Pl. NEMO RK ON ET, VIS; IA Ta (116,20) 11225 12800 Bachrof these has its texture more dense and hard near the symphy- sis. Externally indicated by the narrow line that marks the suture, this compacted part of its mass inecreases in breadth inwards, so as to form, in the transverse section, Pl. X, fig. 110, 116, 119, 120, 130, a triangular area, the base of which in some species describes a hollow quadrant and, joined to the other half, embraces the nearly semi-cireular lumen of a canal occupying the innermost recess of the cavity, somewhat wide above, then contracted, gradually or by means of an oblique ridge, fig. 113, 118, but continued, it will appear, to the lips. On either side of this central canal the alveolar wall presents a longitudinal linear elevation, »lineze eminentes pyra- midis» VAL., upwards ending in a more or less prominent sty- loid process, fig. 111, 113, 114, 118, 122, 123, and continued downwards to the mouth. Between its narrow, even, slightly raised margins is included a linear area, fig. cit. Xx of a some- what duller colour, feebly convex in the Echinus esculentus, fig. 122, slightly concave in the Cidaris papillata, fig. 113, ex- tended to the top of the styloid process, and, below, to not far from the mouth. These two »lineze eminentes» constitute the slide of the tooth, the bed on which this gradually glides downwards in measure as it wears at the free end. Its con- vex and linear back, smooth and glossy on either side of the mesial groove, closes inwardly the semi-circular canal, fig. 110, 116, 120, while each of its sides, feebly concave or convex,
42 SVEN LOVÉN, ECHINOLOGICA.
presents, as already observed by GInSBRECHT,! an area well defined by its want of gloss, fig. 110, 112, 115, 116, 117, 120, 121, 124, x and agreeing in form and extension with the oppo- site area of the slide. 'Phe interval between both areas is filled with a fibrous tissue, Pl. N, fig. 125 +, by means of which the tooth is held tightly fixed. The dull area of the tooth to which this tissue is attached, is roughened and adapted thereunto by means of a sharply defined superficial layer, fig. 126, 127, 128, of densely packed, parallel, slightly fexuous calcified filaments connected transversely or bifurecated here and there, so as to form lengthened and narrow meshes. "They are supported, as seen in a longitudinal section, fig. 127, by short translucent pillars, which, in a transverse section, fig. 128, from the strings being cut off, appear as headed knobs, projecting from the margins of the lamels.
Such is the arrangement of these parts im Cidaris, fig. 110—113, Asthenosoma, fig. 116—-118, Echinothrix, Astropyga, Diadema, fig. 119, Centrostephanus, and others the teeth of which are simply concave on their inner side. It obtains also among the genera having the teeth provided with a carima on the inside, in the Echinus esculentus L., fig. 120-—-129, and E. miliaris LrsKr, the Sphrierechinus granularis LAMcK., the Tri- pneustes esculentus LesKr, the Boletia pileolus LAMCK., the Pseu- doboletia indiana Micn., the Echinocidaris nigra Mor., the Echi- nometra Lucunter L., the Heterocentrus mamillatus L. But in several other forms, as the Echinus angulosus LEsKE, the Strongylocentrus lividus LAMcCK., fig. 130, the Str. francistanus AL. AG., and Str. dröbachensis O. F. M., the Temnopleurus Hardwicki GraYr, the Salmacis sulcata AG., the canal is very much reduced or has entirely disappeared, the pyramid pre- senting a rounded mesial surface conforming to the back of the tooth.
In both great divisions of the Regularia the dental appa- rvatus, Pl. VI, has for its external motor muscles, present every- were, the inter-pyramidal muscles, the five pairs of m. pro- tractores STEWART, mm. pro, (m. comminutores VALENTIN), the five of m. retractores STEWw., mm. re., (m. dilatatores VAL.) and the five of m. radiales STEwW. (ligamenta obliqua externa VAL.).
dö [ET ra ol
BIHANG TILL K. SV. VET.-AHAD. HANDL. BAND 18. AFD. IV. N:01. 43
These last everywhere arise from the peristomal middle of one interradium and are inserted upon the bifurcate ends of the compasses; their function is as yet not properly under- stood. The combination of movements between every two py- ramids and the interjacent rotula are brought about by means of the ten pairs of small rotular muscles; five pairs of m. rot. TN rand five otim. ro.egt., PLIKT fig.189, 42, 44, 45,46, mm the Cidaris papillata LEsSKE; fig. 49 in Echinometra Lucunter L.; fig. 51, in Asthenosoma varium GruBrE. The articular sur- faces of the rotula and the epiphysis present, in the former, near the external end, a pair of oval condyloid eminences, cond., each of them received into a glenoid cavity, gl., of the ad- joining epiphysis; and in the latter, near its inner end, a tu- bercle, tu., received into one of two corresponding hollows, fo., in the rotula. The m. rot. int. are attached to either epiphy- sis at the inner, alveolar side of the tubercle, fig. 42, 45, 49, 51, and inserted upon the rotula close under its projecting upper margin. The mm. rot. ext., fig. 46, are attached to either epiphysis on its inter-muscular side, behind the margin of the glenoidal cavity, and inserted on the sides of the rotula close under its upper margin.
The two principal sets of motor muscles: the protractors and the retractors, are inserted on the outer sides of the py- ramid and have their fixed attachments on the peristome, but in a different manner in the two groups. The protractors in both origmate from the interradium, the retractors from the auricles, but these are in the Cidaridzee interradial, in the Ec- tobranchiates ambulacral. We have had a glance at an early stage of their development in a Cidarid, the still astomous Goniocidaris, Pl. III, fig. 22. Both pairs arise from the so- litary first interradial plate, one of each pair, close together, from a slight eminence. But this solitary plate, at this stage their common support, will gradually disappear through re- absorption, and their attachments will be removed to the first pair of binary plates, and from thence to the following pairs. This we see to have been done in the adult. In the Cidaris papillata, Pl. VI, fig. 39—42, the two long, thin, subtriangu- lar protractors have their narrow, Reed slightly diverging attachments close together near the converging margins of the auricular branches, fig. 39, 5 a; fig. 40, 5 b; fig. 41, 5 5 b. They ascend, expanding and applying themselves to le
44 SVEN LOVÉN, ECHINOLOGICA.
external surface of the pyramid, and are inserted upon the upper half of its convex sides and upon the epiphysis, in the narrow submarginal groove, fig. 40, 5 b; 41, 5 a. Above them, on either side, one of the two retractors takes its origin on a line following the upper arched crest of each branch, and the two pass downwards under the protractors, their fascieles con- verging, become laterally flattened and compressed, and are inserted under the protractors, in the lower continuation of the longitudinal groove that follows the margins of the pyramid, fig. 40, 5 b, 41, 5 a. Thus every single pyramid receives all its museles from one and the same interradium.
It has been seen, above p. 14, Pl. IV, fig. 25, 26, how in the astomous HEctobranchiate the protractors of each pyramid are attached, close together, at first to the adoral margin of one solitary peristomal interradial plate, and later, Pl. V, fig. 30, when this plate has been reabsorbed, to the succeeding pair of iuterradials, — all this as in the Cidaris — but that the Ectobranchiate, very dissimilar in this, has the two retractors of every pyramid attached on different ambulacra, each on a ri- sing auricular branch, fig. 26, 30, 31. "In the adult ASrnis well known, for example in the Echinometra Lucunter L., Pl. VI, fig... 47—49, the origin of the broad and powerful protractors is the same as in the young, on the inside of the low interradial ridge. From thence they ascend with equal breadth and become inserted on the epiphysis and upper sides of the pyramid. With the retractors it is otherwise:
The pyramid 1 has its protractors on 1, its sotnä ata on: Is br 2 20 > IT .05 TING 3 2 III 25 IVER 4 4, TVADSEVIdE 2 D, 5 » HIV OLIN
and the two auricular branches which support the retractors of one and the same pyramid, in growing upwards have strongly diverged and increased the distance between their muscles in arching over their own ambulacrum, to such an extent that their expanded tops sometimes have come te coalesce with those of the branches supporting each a retractor of the nea- rest pyramid, and to bring close together their attachments. The retractors generally have a coarser texture, of larger fas- ciculi, than the protractors, and a darker colour.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:01. 45
The arrangement of these parts in the Asthenosoma va- rium GERUBE, Pl. VI, fig. 50, is that which is typical of the Ectobranchiates. The tender auricles have their stand on the inside of the ambulacral columns. Every entire plate is raised outside the pores near its outer end, which projects under the edge of the interradium, and forms a groove for the slightly expanded base of the auricular branch, which also projects into a heel contiguous to the raised margin of the interradium. The branch then bends over the ambulacrum and joins the opposite branch, the two thus forming a low arch. The stri- kingly thin and feeble auricle, based as it is upon the flexible and constantly moving ambulacrum, is hardly equal to the strain produced by the retractor muscles whieh combine to draw it inward. This is prevented by the action of antago- nistic muscles inserted upon the outer edges of the auricular arch and originating from the longitudinal muscles,! and others inserted on the inner side of the auricular branches and at- tached to the buccal membrane. The retractors of each pyramid arise from the two diverging auricular branches of the two nearest ambulacra, and the protractors from the slight inter- radial ridge; all this as in the other Ectobranchiates.
The great difference between the Regularia Abranchiata and Ectobranchiata in the arrangement of the retractor muscles is worth some consideration. It has been seen that in the for- mer the auricles arise from the interradia, and give attachment to the retractors as well as to the protractors, whereas in the Ectobranchiates they arise from the ambulacra, and give attach- ment to the retractors alone. By this the fundamental dis- tinetion is heightened between the two coordinated constituent systems of the corona, between ambulacra and interradia. It is already great as itis. The ambulacra are heterotropic; their plates are throughout biseriate; all but exclusively they bear the pedicels, and without exception the spheeridia; simple at their first formation they successively unite into compound plates; they grow and move at their own rate, independently; and when they imbricate it is in the adoral direction. The interradia begin in the peristome with a solitary plate, then become binary; they are only exceptionally bearers of pedicels, nowhere of spheeridia; they never are compounded; they grow consistently with the ambulacra, but at a rate of their own,
! SARASIN, Ergebnisse, Ceylon I, p. 93—95, Pl. XII—XIV.
46 SVEN LOVÉN, ECHINOLOGICA.
and when they imbricate it is aborally. We now can add that in the Cidaride they afford the auricles, while in the Ectobranchiates these are borne by the ambulacra. In the re- cent Ectobranchiates, of which many are neonomous, this in- herent dissimilitude, while maintaining its full validity, is ob- scured in the outward aspect by the ambulacra increasing in breadth and forming with the interradia an even set, as also by the spinary system tending to equality and uniformity all over the perisome, covering it with verrucee and spines similar in form and approximating in size. This appearance of con- formity prevalent among the numerous HEchinide, is lesgs marked in the Arbacide and in the Saleniide, of at least oolitie origin; it is effaced in the Echinothurize and Diadematidee, also of remote beginning, which present great contrasts be- tween the two systems, narrow ambulacra of aberrant forms and with peculiar spines, and in certain genera imbricated adorally, while the interradia are imbricated aborally. And in the Cidaride, the oldest of recent Echinoidea, the difference becomes obvious. Their ancestors lived as Perischoechinoids in the Silurian seas, once the home also of Cystoids, in some of which, as in Glyptosphera and Protoerinus, the ambulacra formed part of the perisome, while in others, as in Callocy- stis, they were attached solely by their first adoral plates but for the rest free, movable, reclining on the perisome;! and in numerous others »arms» were directed upwards, arising round the oral region. Perhaps that, when the dental apparatus at first originated in some remote ancestor of the antique Perischoechi- nidee, the ambulacra were yet free and movable, wholly ex- ternal, and nowise internal parts, and thus the interradia alone had to afford, out of their own substance, the supports required for the retractor muscles, and that, when the pyra- mids came into existence in the Ectobranchiates, the ambu- lacra were already fixed, fettered limbs, strong enough to su- stain their auricles.
From the structure of the masticatory parts in the Cidaridee and the Ectobranchiates, their mode of action is easily inferred. The Echinoids are slow animals. In the Regularia the defence is left to the bristling spines and the poisonous forcipes, the opera- tion of catching free and active prey to the agility of the numer- ous, Hexible and contractile pedicels armed with powerful sucking
! See the author's memoir on Pourtalesia, p. 10, 57.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18: AFD. IV. N:0O1. 47
disks, while the armature of the mouth serves the sole pur- pose of grasping the food handed down to it or picked up on the ground on which the animal leads its wandering life. The whole of the maxillary system, homodont and in all its parts of a compact, solid tissue, constitutes a reversed cone, the vertex of which is formed by the points of the teeth, the nearly erect position and outward curvature of which combine to make them a five-bladed powerful instrument adapted by their hard and trenchant cuspidate crowns to biting and tearing to pieces even fixed or else resisting objects, Corals, Balani, Serpulee; governed as they are by powerful muscles, the interpyramidals which by contraction close their gape so as to give it a firm hold of whatever it seizes; the protractors, attached low, in- serted high, thus capable of protruding it forcibly far beyond the peristome; the lifting retractors attached high, inserted low, assisting in opening the gape; and in order to secure to the whole apparatus the greatest possible freedom of move- ment, a pliant buccal membrane has been brought about by secondary reabsorption of legitimately preexisting parts, set at work simultaneously with the act of dentition.
I have elsewhere! given a description and figure, repeated on next page, of the internal aspect of the peristomal region in the Discoidea cylindrica, the low form, as described by CoTTEAU? and WkricHt.? The stoma is very slightly oval, the antero- posterior diameter III—53 being somewhat the longer. The ambulacra project a little more than the broad interradia. The aurieles rise on the ambulacra and recline with their basilar portions upon them as well as upon the strongly swel- ling columns of the interradia. "Their upper parts are more erect. The upper margin is thin, and presents at its ambula- cral angle a projecting ear made distinct by a slight impres- sion. Each auricular branch is connected with that of the nearest ambulacrum by a wall rising from the interradium, nearly attaining the height of the auricle, almost linear at its upper margin and slightly hollow on the adoral surface. "The sutures which define the auricular branches and the first in-
!' On a recent form of the Echinoconide. Bihang till K. Svenska Vet. Akad. Handlingar, XIII, IV, n:o 10.
> Paléontologie francaise, VII, P1. 1010, f. 1.
3 British fossil Echinodermata of the Cretaceous formations, pl. XLVTI, f. 2.
48 SVEN LOVÉN, ECHINOLOGIOCA.
terradial plates as well as those that divide the interradial wall, are all distinct!
ån Te d
Discoidea cylindrica AG. forma vulgaris; the peristome from the inside.
Another specimen, the forma elatior of the same spe- cies,? shows some remarkable differences. The branches of the auricles are higher, more free and erect in their upper por- tions, and present at the top the same slightly tumid pro- jection. The interradial wall which connects their pairs does not reach their height but is much lower, and even. The sutures are all obliterated, but a distinct impression marks the limit of the interradial wall toward the branch. When compared in corresponding parts with the lower form, the diffe- rence is great and almost seems to indicate specific distinction, the more so as at the same time the interradial walls are much narrower and proportionally lower in the elevated form than
! Compare DUNCAN and SLADEN, Linnean Society's Journal. Zoology, XX, p. 48 and Ann. Nat. History, September 1889. 2 CorTEAU I ce. pl 1011 f. 1. '—= WRriciw Ive: pl XLVIL fi
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:01. 49
in the hemispherical. But this question I must leave to be decided by those who have at their disposal a greater number of specimens.
Discoidea cylindrica AG., forma elatior, the peristome from the inside.
In the Galerites Albogalerus LrsKE the auricular system, as forestalled already by DESMOoULINS,! is constructed upon the same principle as in the Discoidea, but modified in a peculiar way.? The auricular branches of each ambulacrum, well defined by distinct sutures, are slightly more separating than in the lower form of Discoidea cylindrica, proportionally longer, and nearly as slender as in the elevated form, and, like either of them, provided on the ambulacral side of the top with a mi- nute and glossy projection. The broad interradial wall, which equals the auricle in height, has a middle convexity between two rather deep impressions. Thus far the conformity with
i Etudes, 1 op. 25, 189. ? See woodceut on the next page.
50 SVEN LOVÉN, ECHINOLOGICA.
Discoidea is perfect, and still, at the first sight, there seems to be a great discrepancy. In the elevated form of the Dis- coidea the entire system, though not as erect as in the other Regularia, is largely free and projecting, in the lower form it adheres to the tumid interradials to a greater extent, but
Galerites Albogalerus LESKE. The peristome from the inside.
Section through the interradium and the auricle.
still projects not a little above it with its marginal part. In the Galerites this lowering of the auricles is carried to the extreme. All around the peristome the whole system reclines upon the test, to which it is soldered in its whole length, and its upper margin is made distinct only by a slight impression.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:o1. 51
As far as I have been able to make out the structure of these parts in the other genera of the Echinoconidee, it seems to be essentially the same in all. In the Pygaster semisulca- tus PHILL.! the five or six first plates of both columns in each ambulacrum expand laterally, while the poral zones converge and at the same time become gradually higher so as to form by their succession two ridges rising adorally and terminating with a slightly concave surface that descends rather steeply toward the peristome. The section shows the gradual increase in height of the ambulacral plates 8 to 1, and their ending sur- mounted by an overhanging projection which seems to come into view between the tops of the two first ambulacrals. The same appears to hold good in Holectypus. In the Anortho- pygus orbicularis CorrrEaAU the raising up of the compressed peristomal plates of the ambulacrum is very distinct, as is also the suture between them and the interradium, which, as by rule, forms the greater part of the branchial sinus. Thanks to the kind liberality of M. CorttrEau I have been able, by ta- king a cast of a specimen of Pileus hemispheericus DEsor? in his collection, to convince myself that the same structure main- tains also in that genus.
« When the auricular system thus described is compared with that in any other among the Regularia, a striking dif- ference is found in the smallness of the stoma in proportion to the diameter of the test. In those groups this was found to vary between 0,59 and 0,22 of the total diameter, in the Pygaster semisulcatus PuHIiLL. it is 0,21 of the same, in the Galerites Albogalerus LESKE 0,13, in the Discoidea cylindrica LAMcK 0,10. The loss of substance through reabsorption at the peristome is also less; in all the five interradia of the adult Pygaster semisulcatus,? Holectypus depressus LEsKE,t Discoidea cylindrica,? the solitary first plate is preserved to no small extent. At the same time the distance between the opposite tops of two auricles is, in the Discoidea, 0,24 of that of the test, while the diameter of the stoma is 0,10. In the Diadema saxatile L. the same measures are 0,60 and 0,48; in the Echi- nus esculentus 0,33 and 0,24, in the Echinometra Lucunter L.
! See my paper on a recent form of the Echinoconide, p. 7, fig. 12, 13.
2 Paléontologie francaise, Terrain Jurassique, IX, pl. 115, fig. 1.
3 On a recent form of the Echinoconide&e, P1. 2, fig. 12.
3 Etudes sur les Echinoidées, P1. XIV, fig. 124. 5 See woodecut, pag. 48.
D2 SVEN LOVÉN, ECHINOLOGICA.
0,57, and 0,44, which shows that the spreading of the auri- cular circle is much greater in the Echinoconid&e. The auri- cles and the interradial walls that connect them, are by no means as erect as in the Cidaride or the Ectobranchiates, and recline upon the test, which is more thickened, particularly in the interradia. The aurieles evidently arise from the ambu- lacra, not, as in the Cidaride, from the interradia, and it may be safely inferred that the ambulacral columns were not, as in these last and in the Echinothurize, continued to the mouth, but, as in the Echinide, had their adoral termination in the peristome. The pairs of auricular branches do not unite at the top over the ambulacrum, but while they bend towards each other and their projecting ears overhang a little, they, nevertheless, are widely separated. In this they agree with the Cidaridsée and among the Ectobranchiates with Echinocida- ris and Arbacia, and to a certain degree with Strongylocen- trus, Lytechinus, Tripneustes, Boletia, Stomopneustes, Temno- pleurus, Mespilia, Amblypneustes, in which the slender au- ricles feebly incline towards each other, but remain separate, or little more than touch at their expanded tops; while they differ widely from the Diadematide and Echinometridee in which the branches are largely coalescing.
The extent to which these peculiarities in the auricular system of the Echinoconidee, its small dimensions, the reclining position of its slender branches, in connexion with the slight de- viation in the stoma from the circular form, — not consistent, it seems, with a concentric homodont condition of the jaws — may have been attended with modifications also in the maxillary apparatus, further researches will have to demonstrate. Mean- while I shall here offer some remarks on the form of the pyramids in the more normal Discoidea cylindrica, in each of two speci- mens of which were found three tolerably well preserved halves, and compare them with corresponding parts of Cidaris, Echi- nometra and Asthenosoma.
In the Cidaride, as represented by the Cidaris papillata LESKE, the two halves of the pyramid are united through 0,88 of their whole length, from the mouth to far above the inner angles of the lateral wings, and almost to the level of the tops of the supra-alveolar processes which, accordingly, are separated only by a shallow notch. In the Echinometra and the Asthenosoma the symphysis terminates already at 0,6 of
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:01. 53
« Lilievsll dät. &sx€
Pyramids: 1, Discoidea cylindrica AG. 2, Cidaris papillata LESKE. 3, Echi- nometra Lucunter L. 4, Asthenosoma varium GRUBE.
54 SVEN LOVÉN, ECHINOLOGICA.
the length and the upper parts of the wings become separated by a large and deep celeft. In the Cidarids the halves are more massive than in the two Ectobranchiates, and the alveolar cavity less spacious. In the former, also, the aboral truncated margins of the wings slope inward, b, so as to form with the inner margin a right, or obtuse, angle, while the external angle is acute; whereas in Echinometra and Asthenosoma the margin of the wing rises inward, thus causing the inner angle to become acute, and the external nearly right.
The pyramid of the Discoidea cylindrica is much broader in proportion to its length than those of the Cidarids or Ecto- branchiates. Their halves have more of the Cidarid. They are upon the whole more massive. 'The symphysis reaches 0,74 of the whole length, and, consequently, the »foramen» between the upper parts of the halves is much less deep than in the other Ectobranchiates, but not fully as shallow as in the Cidaris papillata. The external surface is not as regularly convex as in the Cidaris, but the middle prominence is less marked and less broad than in the Echinidzee, and the depressions on either side of it much slighter, the margins not as thin as in the Echinometra, nor made distinet by a conspicuous furrow as in the Cidaris. The aboral margin of the wing, when seen from the cavity, does not slope inward as much as in the Cidarids, but is far from rising as in the Echinometra or Asthenosoma. The supra-alveolar process is not quite as high as in the Ci- daris, but, seen from the lateral face and from above, it is fully as massive, and somewhat truncated. The area of the sym- physis is broader than in any genus of the Regularia. The dental slide is somewhat shorter than that area, and the styloid processes of the line&e eminentes have not been very prominent, Pl. X, fig. 114, 115. The two linee are very close together, and a canal seems not to have existed. The roughened area, to which the intervening fibrous tissue has been affixed, is distinct. |
It would be of no little interest to learn something more respecting the dental apparatus in the other Echinoconidee, particularly in the Galerites Albogalerus LESKE, whose au- rieles by their strange reclining posture seem to foreshow con- siderable modifications in the pyramids. The frequent occur- rence of this species in the chalk seems to promise well for a careful search among numerous specimens easily procured.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:01. 55
Meanwhile it seems allowable to expect that the modifica- tions of these parts in the Galerites will be found to be de- viations from the type of the Regularia to which the Echi- noconid&e are allied in other respects. They are regular, the mouth being central and the calyx right over it; their am- bulacral plates compound in the same manner, and they had external gills. The position of the excretory opening is of but secondary importance.
The earliest account of the dental system of the Clypea- stride is found in the work of KLEIn,! and, after him, in that of Parra? a good description quoted by DEsmouLins and Jo- HANNES MÖLLER. Some particulars relating to the Clypeaster Rangianus were added by DEsMouLISs.? JOHANNES MÖLLER, who showed that in this group the same principal parts are present as in the Regularia, five pyramids, ten epiphyses and five rofule, but that the compasses are absent, described and figured with great care the whole apparatus in Clypeaster, Arachnoides and Mellita. ALEXANDER ÅGASsIZ? represented it in »Clypeaster humilis:, Cl. reticulatus L., and Lobophora aurita LESKE.
The dental system of Clypeaster reticulatus L., Pl. VII, fig. 52—062, Pl. VIII, fig. 65—72, Pl. XI, fig. 144, when com- pared with that of the Regularia, for instance that of Echino- metra Lucunter L., Pl. VII, fig. 63, 64, presents not a few distinctive features. In the Echinometra its greatest dimen- sion is the vertical, in the Clypeaster the horizontal. In the former the whole of the five concentrically arranged, uniform and equal pyramids constitutes a regular inverted cone, the horizontal section of which is circular; in the Clypeaster it forms an elevated pentagonal star, the sides of which, slightly reentering, are unequal, fig. 144. Tf the largest side, the 5,is taken — 1, the 2 and 3 are each = 0,s6, and the 1 and 4, of greater reentering depth, each = 0,67. In the Echinometra the alveoles are tending to close interiorly, the wings being
! Dispositio, p. 45, t. XXXII, fig. h—s
> Descripeion de differentes piezas de Historia Natural, Havanna 1787, p. 137, P1. 22, fig. 1—10.
3 Etudes, p. 66, 185, P1 I.
4 Ueber den Bau d. Echinodermen, p. 14, pl. VII fig. 13 —16. Berl. Ab-
handl. 1854. 5 Revision, p. 688, P1. XI a, XXVIII, XXX fig. 1.
536 SVEN LOVÉN, ECHINOLOGICA.
convergent, in the Clypeaster they are wide-open, fig. 57, the inner wings being very short, and divergent. The figure formed by the supra-alveolar crests, fig. 144, is not circular nor pentagonal, but obovate, contracted posteriorly, and of a narrow compass, its longest radius, the 5, being within half the length of the pyramid. If the distance between the middle of the rotule I and V is taken = 1, that between the rotulze I and IV, IV and V, is = 1,12, and the distance: between IL and III, IV and III =1,)035. The increase of the longitudinal and antero-posterior axis of the body, and the bilateral sym- metry on either side of it, the 1 and 4 being broader in proportion internally than the 2, 3 and 5, are thus expressed in the general form of the dental system. If the specimen is turned and the mouth examined the same proportions are found to reappear likewise in the size of the teeth, Pl. VII, fig... 52, 60, 61, Pl; , XI, fig, 149, of! which then omsktne largest and most prominent, then the 2 and 3, while the 1 and 4 are the smallest. The points of 5, 2 and 3 meet to- gether and keep the teeth 1 and 4 apart from one another. When a half-pyramid of Clypeaster reticulatus L. and a cor- responding one of, for instance, the Echinometra Lucunter L.! are placed side by side, with the inside of the alveole and the symphysis up, the support of the tooth will be found to agree very closely in both. "There is in either the corres- ponding half of the nearly vertical, linear, incurved slide for the back of the tooth, s. de. fig. 52, 57, 60, ending upward in a styloid projection, prominent in the Echinometra, sessile in the Clypeaster. But there the resemblance ceases. In the former the entire area of the symphysis is vertical, narrow and lIunate, its external outline being regularly arcuated, and it ends adorally under an acute angle. In the Clypeaster, fig. 60, the same area is narrow and pointed, also, in its upper part, only gradually widening downward, for about 0,43 of the length of the dental slide. But at that point its upper outline is strongly diverted outwards at an obtuse angle, while the under outline is also directed outward, and the two lines, joining at the rounded external extremity, circum- seribe an expanded, tongue-shaped surface, symph.; about half as long again as the dental slide is high. This large area of the symphysis answers to the narrow and simply lunate one
! Wood engraving p. 53, fig. 3, c. 5 Jå Ed 2
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0o1. 57
in the Echinometra, and it is seen that the pyramid of the Clypeaster is drawn out exteriorly into a hump, and that the greater mass of it, which in the former lies on the oesopha- geal side, is thrown outward in the Clypeaster. The pyramid, constituted by the two halves, which are united at the sym- physis by fibrous tissue, thus becomes expanded horizontally and reclining, not upright, and the whole of the five pyra- mids forms a comparatively flattened, stellate pentagon the rays of which are ambulacral. Seen from above, fig. 57, each pyramid has the outlines of an arrow-head. The two sides are feebly arcuated; the external border forms a reentering angle; the point, the interior angle, is truncated and exca- vated over the dental groove. The upper surface, that of the large hump, is slightly concave, its sides somewhat rising, the lateral wings rather sloping externally, the internal angle strongly raised, and the mesial suture marked with a narrow ridge. It exhibits a distinct division into a middle part, its body, and two lateral parts. The middle part, corp. fig. 52, 57, 58, equally divided by the mesial suture, is compact, the lateral parts lamellate. At its inner, truncated end the middle part is raised into a transverse crest cr., fig. 57, only a little above the styloid terminations of the dental slide, and ending on either side in a thickened process, pr. sup., fig. 52, 57, 60, the supra-alveolar process, and this is cut down vertically, leaving a ledge on which rests the epiphysis fig. 52, 57, 59 ep., a simple, fattened, oval plate lower and produced beyond the process interiorly, slightly convex and glossy in its middle, laterally flush with the surface of the pyramid. Very similar in form to either of the two epiphyses, between which it is contained, 1s the rotula, fig. 57, ro., fig. 62, ambulacral in po- sition, likewise a minute simple plate, pointed interiorly, slightly concave on the sides, and broad at the upper margin.
The lower surface of the pyramid, fig. 58, presents the same division into a compact middle body, corp., larger in pro- portion than above, and two lateral more narrow lamellated borders. The middle body is concave between the projecting borders, and the mesial suture marked by a prominent ridge that strengthens adorally and forms the lower, labial process, pr. lab., which joins the oral termination of the dental slide and in its emarginated termination receives the end of the tooth. Near this point the ridge becomes the septum between
58 SVEN LOVÉN, ECHINOLOGICA.
two oblong, high and spacious excavations, fo., fig. 52,53, 56, 58, Pl. VIII, fig. 66, arched over the auricles and the motory muscles, and reaching sometimes to near the upper surface and the dental slide.
The sides of the pyramid, fiske. 59, are the two extended and nearly flat lateral surfaces, that give attachment to the inter-pyramidal muscles, fig. 52, 57, lam. int., 58, 59, 60. They agree in size and form. Each of them is marked by concentric curves of accretion, and divided, by a faintly sig- moidal row of large holes running from the labial process to the middle of the external margin, into an upper and a lower area. From that row there radiate, upwards and downwards, like the two vanes of a feather, two series of slightly elevated ribs pierced by regular rows of smaller holes. There are no transverse ridges like those in the Regularia for the attachment of the muscles, fig. 63. The lateral sur- face is a thin sheet, lam. int., connected with the compact main body of the pyramid in the following manner.
As in all the dentate Echinoids, the density of the calcified tissue of the pyramid varies in different parts, Pl. VIII, fig. 66—72. It attains its highest degree of hardness and is all but homogeneous in the two strong ridges stretching from the labial process, one along either side of the middle body, Pl. VIL, fig. 158 X+ 590Xx, PIUVIIL figs606:xT Almostlequalmnysoc lidity is the reticular texture of each half-pyramid at the mesial symphysis. It there forms a distinct vertical zone consisting of regular layers of very minute meshes, Pl. VIII, fig. 66 XX. 67 X, disposed longitudinally and, less distinctly, transversely. It is very narrow at its upper margiu, where it gives rise to the mesial ridge, increases downward in thickness, by multiplying its layers, and is rather strong in the septum of the fossee, fig. 58, 66. Inwards it continues towards the dental support, of which it forms an essential part, Pl. X, fig. 110, 116, 119, 120, 130: All along the sym- physis this compacted tissue is closely accompanied in each half-pyramid by a rather irregular network, fig. 67, which has the appearance of being derived from it, but assumes, somewhat abruptly, a transverse direction and a looser consi- stence. 'The meshes become wider and stretched in the trans- verse direction, fig. 68, 69, their sides are drawn out into fi- laments connected by minute bars, and finally collect together
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:01. 59
into separate lamels, fig. 70, 71. This is manifest in the dorsal as well as in the ventral aspect of the middle body. On either side of its mesial ridge, Pl. VII, fig. 57, 58, a suc- cession of beams is seen to divaricate, some thick and strong, others more slender and less distinct, all imbedded in a fibrous mass of looser consistence. Along a line marking, above, the half breadth of each half-pyramid, and, below, its marginal third part, the connecting mass disappears, its strings forming delicate bows between the beams and interlacing, and the beams, partially bifurcated, stand forth as the upper and un- der edges of lamellar partitions arranged fanlike, fig. 52, 59, 60, all around, from the lower labial process to beyond the upper, supra-alveolar, process. The laterally produced com- pact middle body from which they issue, presents an upper, broader, sloping support and a lower more narrow, and where both meet, Pl. VIII, fig. 66, rh., they form a rachis, of a dense texture, from which the lamels radiate, fig. 59, rh, like the vanes from the shaft, the upper ones large, the lower smaller. They extend laterally till they reach one of the five planes that divide the dental star into the five pyramids. Close be- fore attaining that plane, every lamel, upper and lower, is parted into a series of short branches, fig. 71, which diverge right and left, while, by repeated ramification, they subdivide into branchlets that spread out, fig. 72, and give rise to the layers of closer and closer net-work, which constitute the thin but strong calcareous sheet that affords to the inter-pyramidal muscles their attachments and their insertions. Outside, the direction of each lamellar partition is made apparent through a slight and narrow elevation, Pl. VII, fig. 59, and a series of noles, places of exit for the vascular and nervous systems supplying the muscles. "There seems to be one hole for every lobe, and at the rachis as many larger holes as there are di- varicating branches.
In consequence of the radiate disposition of the partitions the lateral inter-muscular sheet, which is the result of their repeated divisions, attains a great expansion, widely surpas- sing, all around, the area of the symphysis, fig. 52, 60. Its outline, fig. 59, is upon the whole sub-elliptic, sonewhat leng- thened and broader exteriorly. Its inner, alveolar part, the interior wing, al. int., fig. 52, 59, 60, the representative of the whole inter-muscular surface in the Regularia, is very small;
60 SVEN LOVÉN, ECHINOLOGICA.
the large external wing, al. ext., which makes all but the whole of the inter-muscular surface and is developed from the hump of the pyramid, is without equivalent in those forms. In Clypeaster the two wings, al. int. and al. ext. are separated from one another by an interval of peculiar structure, a tri- angular area, tr. fig. 59, the base of which coincides with the ledge of the epiphysis, while its point is directed downward to the labial process. Outside, it is marked by the absence or scarcity of the holes and the deviating, transverse direction of the faintly elevated lines. It indicates, from without, the space within which that part of the compact body which forms tbe dental slide joins the inter-muscular sheet, as seen in the section, Pl. X, fig. 135 x x. Tf this sheet is carefully removed, Pl. VIII, fig. 65, it is seen that the lamellar structure, emi- nently regular through almost its whole extent, is interrupted along the external side of the triangle and replaced by an irregular, invertedly dendroid structure proceeding from a dense and solid part beneath the supra-alveolar process, and on one side sending off lamellar branchlets, which enclose shallow lacunes, towards the regular lamels of the external wing, on the other spreading them in the internal.
The paired auricular branches that are received each in- to one of the two fosse of every pyramid, Pl. VII, fig. 52, 54, 55, 56, arise from the ambulacra, and have between them the very minute and narrow interradium,! often partially or wholly overgrown by their expanded base. They belong each to a different ambulacrum, the nearest column right and left, in such a manner that, for instance, the fossa a of the pyra- mid 5, fo. 5 a, fig. 58, receives its auricular branch from V b, fig. 55, and the fossa b its branch from I a, and so forth, as it is in the Ectobranchiates. The two of one pyramid are near together, and their bases almost parallel, each branch rising close to the external margin of its column. "They are smaller and weaker in proportion than in the regular Echi- noids, compressed radially, not concentrically, and very slightly bent adorally; the tumid tops lean interradially and adorally. A process derived from the proper tissue of the ambulacrum is the core of each branch, and is covered with a thick coat of that other peculiar calcified tissue, the luxuriant peritoneal system that lines with a regularly pierced crust the whole
i Etudes, P1; XLMIE
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:o1. 61
inside of the skeleton, ambulacra and interradia, and divides with stalactite-like pillars, props, and partitions, the visceral cavity into compartments. On the interradial side of the au- ricular branch this covering is smooth, adorally, at the base, diverging sideways; on the ambulacral side it sends forth off- shoots between the rows of pores, and aborally continues in in a narrow ridge. The inner, adoral border of each branch presents a breach, a deep and narrow furrow running from near the top towards the base and laying bare the interior. Its projecting margins give attachment to the motor muscles of the pyramid, Pl. VII, fig. 52—56.
An auricle of Clypeaster reticulatus L., and one of its branches showing the furrow.
znt.
Transverse section of the auricle;" the core int. the interradium.
If a vertical section is made of a half-pyramid in the di- rection indicated by the line B in fig. 58, the fossa a is laid open with its auricle, and the retractor. This muscle, simple in the regular Gnathostomes, is here bipartite, represented by two separate parts, m. re. Z and m. re. 2. In fig. 32 this last is to a great extent concealed behind the auricle. When this is removed, fig. 53, both parts are seen; when the auricle is preserved, but the pyramid taken away, they are both visible: fig. 54, from the interradial side: fig. 55, from above; and, when a section is made through the pyramid by the line A in fig. 52, and viewed in the direction of the arrow, as shown
62 SVEN LOVÉN, ECHINOLOGICA.
in fig. 56, the mm. re. 2 alone are to be seen. Each mm. re. 1 is thin, of a somewhat rhomboidal shape, and is attached to the lower half or two thirds of the margin of the furrow on the inner border of the auricle, whence it extends horizontally and adorally while it gradually thickens and becomes convo- lute, fig. 54, 55; both m. re. 1. are inserted on either side of the septum, fig. 58, in two diverging, hooked impressions.
Of the m. re. 2, the aboral parts of the retractors, each is attached to the auricle in horse-shoe form close under the crest of its top. They are rather thick at the origin and thin off downwards, closely contiguous to the m. re. Z and sprea- ding triangularly, and have their very narrow lines of inser- tion on either side of the septum abutting to those of the 2». re. 1 at their aboral ends, fig. 53, 54, 55, 56,-58.
The protractors, m. pro., fig. 53, 54, 56, are two small muscles attached to the inner surface of the test, interradially, but on the expanded base of the aurieles. They ascend, flatte- ning and broadening, and insert themselves on the crest of the septum, between the m. re. 2 in two short linear impres- sions, fig. 58.
Of the alveolar wall of the pyramid the compacted tissue does not occupy as broad a central part as in the Regularia, and there is no central canal. The two »linezxe eminentes»>, therefore, are contiguous at the symphysis, Pl. X, fig. 131, 132. Above, they terminate with two points, representing the styloid processes of the Regularia, but sessile. The dull, rough area of each linea, x, extends with all but the same breadth through nearly two thirds of the length, and then gradually contracts to half its breadth near the lips, fig. 132.
As in the Regularia the tooth is composed of two distinct parts, the lamellar body, the »Zahnkörper» of GIESBRECHT,! which is applied to the slide, and the prismal part, which in the Echinide forms the keel, the carina VaAL., that stands out into the cavity, and in the Cidaridee lines the hollow of its adoral groove, the petrous portion of the body being in both produced, beyond the more friable part, into the pointed apex. In Clypeaster, fig. 131, the keel is much longer in proportion to the body of which its basis occupies nearly the entire breadth, and forms the main mass of the tooth, which is very high,
tes IA
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND18. AFD. IV. N:01. 63 compressed, moderately arcuated, convex towards the slide, Pl. VALT sjig.152,-60: The; back; PliX,/ fig. 133, is marked with a longitudinal, mesial, rounded elevation. The dull, roughened, superficial layer, X, bordered by the narrow and glossy rims, in the upper part occupies the whole breadth of the back, then contracts and in the lower part is confined to this eleva- tion. The body of the tooth fills the dental groove, fig. 134, and in the interspace between the two roughened areas, is seen the fibrous tissue, X. The sides of the compressed tooth, the expanded keel, are concave, and, as far as contained in its matrix-sac, roughened and dull, while the crown, that pro- jects into the pharynx, is glossy on all sides. It is not a cuspidate crown as in the Regularia, with the point of its body projecting beyond the keel, but the broad prismal mass of the keel, Pl. XI, fig. 149, 150, containing bundles of diffe- rent hardness, and thus forming rounded tubercles, is enclosed by the harder lamellar body, and both together present an oblique section, oblong in shape, wedgelike at its inner end, and bevelled off on the sides by friction against the other eetosckhe, tooth. >, Bl: Vik, fig. 52 ,60Z,.Pl: XT, fig: T49is much the larger and the crown seen sideways makes a greater angle against its middle line, than in the 2 and 3, and the 1 and 4, which are the smallest, fig. 60, fig. 149.
JOHANNES MÖLLER described the dental system of the Arach- noides Placenta L., and gave an exact and correctly oriented figure of it.! It is lower than that of the Clypeaster reticu- latus L., stellate, Pl. XI, fig. 146, the rays long, the front one, 2 b, 3 a, slightly produced, the reentering angles much deeper. The sides are bilaterally unequal; if the 5, which is higher than the others, is taken = 1, the 2 and 3 are = 0,88, the 1 and 4 = 0,74. The elevated figure formed by the crests of the alveoles is not ovate, but pentagonal, unconformable, its salient angles coinciding with the reentering angles of the star. The dental slide is almost rectilinear, inclined at about 16”, Pl. VIII, fig. 73, 74. "The area of the symphysis has no upper pointed part; its outline is at once diverted exteriorly at an obtuse angle, and in joming the lower almost horizon- tal outline, which is expanded sub-labially, circumseribes a compact hump half as long as the entire lateral area of the
1 Ueber den Bau der Echinodermen, Berl. Abh. 1854, p. 75, P1. VII, fig. 13.
64 SVEN LOVÉN, ECHINOLOGICA.
pyramid. Seen from above, the pyramid has the form of an arrowhead, fig. 75, with the sides nearly straight and the external angle reentering deeply between the elongated, tape- ring wings. The supra-alveolar crest, cr., which in the Cly- peaster is transverse, here arises on either half-pyramid with one of two elevated diverging branches that terminate each in a broad supra-alveolar process bearing at its lateral detrun- cated end the minute and very thin and low, lamellar epi- physis, fig. 73, 75. The exceptional form of therrotula, jag: 73, 77 a, b, was remarked by JOoHANNES MÖLLER. Its lower part, contained between the epiphyses, is compressed, the up- per surface has a rounded knob, and the expanded margins are unequally bilobate, the larger lobe, one of the two inner ones, being directed, symmetrically, in I and V towards the longitudinal axis, in II and IV likewise, and forwards, in III, towards the IT. The lower surface of the pyramid, fig. 76, is concave, the mesial sutural ridge strong and accompanied on either side by another elevated line; the lamellar fringe is narrow; there are no excavations for the auricles. The labial process is large and prominent. The sides of the pyramid, fig. 73, the inter-muscular sheets, are very long, lanceolate, the rachis produced, fig. 74; the series of larger holes conspi- cuous, but the radiating ribs obseure and imperforate. The triangle, tr. fig. 73, is well marked, broad at the epiphysis, and smooth. The inner wing is very short, and nearly devoid of lamellar partitions. The auricles, see woodeut p. 73, are small; they arise from the ambulacra, very close together, even conti- guous, the first interradial plate being always very minute, often suppressed. ”'PIhe retractor muscles, m. re. fig. 73, are horizontal, their horseshoe-shaped attachment being under the crest of the auricles, their insertions on either side of the su- tural ridge in a hollow under the base of the prominent la- bial process, fig. 76. The very slender protractor muscles m. pro., are attached on the auricles close together at the junce- tion line of these, between the retractors, and ascend right upwards, being inserted on either side of the mesial ridge at its outer” third part” ThReECteethy PisopIN Nog Nr 78, Pl. XI, fig. 146, are long, very slightly curved inward, high, compressed, thickened adorally; the 5 much the larger, not far from right-angled at the crown end.
1 Etaodes, P1. LI, fig. 247—250.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0o1. 65
In the Arachnoides Zelandiee GRAY, fig. 79. the exterior wing is very long and pointed, in particular that of 2b 3 a, answering to III. The interior wing is very short.
The dental system of the Encope emarginata LEsKE, Pl. VIII, fig. 80—85, Pl. XI, fig. 148, is a low star with rather short rays, and not very unequal sides, the 5 being to 2 and 3 astilitol :0,92,;-tol I and;4,;as:1.to,0;88: The figure, of: theral: veolar ambitus is decagonal, the supra-alveolar crests extend- ing beyond the margins at the five reentering angles, while the wings are produced on the five rays, the Za 5b, 5a 4b, less so on the rays I and V. The dental slide, fig. 80, 81, 83, s. de., is not concave but even slightly convex, recumbent at an angle of about 10”.
The area of the symphysis is not in the least expanded outwards, but downwards, adorally, and thus has a some- what triangular form, fig. 83. The pyramid seen from above, fig. 81, has the external angle only slightly reentering. As there is ho hump, and the dental slide is nearly horizontal, the upper arrow-shaped surface is formed of the large and open alveolar cavity bordered by the inner wings, al. int., the crest, cr., and the supra-alveolar process, pr. su. The central com- pact part is level, narrow, expanding outwards; the largely developed lamellar framework of the inner wings is raised and convex, and is infleceted externally, arching over a deep lacune, which intervenes between it and the crest and penetrates to the intermuscular sheet, fig. S1, 83, 84. The dental slide, s. de., nearly reaches the external margin, and this is formed by a double tuberosity of the almost transverse crest, which on either side is produced into the supra-alveolar process, that sup- ports the minute, simple and low, lamellar, epiphysis. The ro- tula, fig. 81, 85, is likewise simple. On the inferior, arrow- shaped surface of the pyramid the middle compact part is le- vel, narrow and sunk, the lamellar fringe rising and broaden- ing outwards. The mesial ridge is distinct, divided at the external border into the marginal bifurcated tuberosity. The labial process is broad and prominent. The lateral surfaces of the pyramid, the intermuscular sheets, are oblong, truncated adorally and emarginate above for the epiphysis. The rachis with its series of holes divides it diagonally in two areas of not very wunequal size, with distinct curves of aceretion and
5)
66 SVEN LOVÉN, ECHINOLOGICA.
radiating perforations. Owing to the recumbent position of the dental slide, the triangular area, tr., comes to rest upon the rachis, and the inner wing almost to coincide with the upper area. The triangle, tr., is long, narrow and smooth, and when the intermuscular sheet is removed, fig. 84, it is seen to be solid altogether. 'The lamellar partitions, fig. 83, 84, of the inner wing are nearly as regular as those of the outer wing, partly dendritic; they are joimed to the adoral border of the triangular body by a few short branches only, that leave between them large lacunes, opened when the inter-muscular sheet is taken away. The inner wing thus has become very large in proportion, fig. 80, S$1, 84. The minute auricles, see woodcut, p. 73, arise from the interradium, which is broad, and are united into one single piece for each tooth, flattened con- centrically, rather narrow at the base, then expanded, bilobate, and contracted, truncated at the top. Along the margin, on either side, are attached the thin, horizontally directed retrac- tors, fig. 80, m. re., which are inserted, on the inferior side of the pyramid, in a prominent horse-shoe-shaped, walled impres- sion, fig. 52. The very slender protractors, fig. 80, m. pro., which are attached, close together, near the top margin of the auricle, are inserted on the tuberosities near the external margin of the pyramid. The teeth, Pl. VIII, fig. 80, 83, Pl. XL fig. 148, are long, high, curved inward, the 5 largest, then the 1 and 4, the 2 and 3 smaller, the crown somewhat concave, the back prominent adorally. :
The Echinarachnius Parma LamMcK., Pl. IX, fig. 86—93, Pl. X, fig. 135, 186, 137, 138, Pl. XI, fig. 142, 147, 151, has the dental system rather high, stellate, with the rays short and broad, the ray 2b 3 a, answering to the ambulacrum IIT, slightly longer. The sides are symmetrically slightly unequal, the 5 being torlkand M4=150)7/6'"tor21 and” =" X0 PSYKE alveolar ambitus is as that of the Encope emarginata LESKE, the supra-alveolar crests exceeding the margins of the reenter- ing angles. The dental slide is feebly convex. recumbent at an angle of about 15”. The area of the symphysis, less poimnted above, is less expanded below, fig. S9, not far from li- near. The pyramid, in its dorsal aspect, fig. 87, is like that of Encope with the deep lacune between the crest and the inner wing larger, fig. 87, 89, 90, the mesial tuber in the external angle entire, the supra-alveolar process strong. The
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:01. 67
epiphysis and the rotula fig. 91, 92, both arcuated below, elongated, equal, very low, thin, the upper margin of the ro- tula expanded internally, the lower margin tumid externally. The ventral surface of the pyramid, fig. S8, is like that of the Encope, level in the interno-external direction, the tuberosity of the external angle slightly bipartite, the labial process broad. The lateral surfaces of the pyramid, fig. 86, 89, 90, ovate, largely emarginate for the epiphysis. The rachis with its series of holes divides it diagonally in two unequal areas, the upper one conspicuously the larger. The curves of aceretion are dense and distinct. The radiating series of per- forations, to a great part conspicuous in the lower area, are few and scattered in the upper. The triangular area, tr., is very broad at its excavated base under the epiphysis; it di- vides the upper area in two nearly equal halves, the inner wing being the other half; it is smooth, marked with incur- vated lines of aceretion parallel to the emargination. When the intermuscular sheet is removed, the tr. presents through- out a succession of irregularly disposed partitions and large lacunes, partly opened, fig. 89, 90. "The radiating lamellar partitions of the external wing are regular, those of the in- ternal less so, interlacing, dendritic. "The auricles, fig. 93, like those of Encope, arise from the interradium and are united into one single piece for each tooth, flattened, slightly lobate. Along its margins the two retractors are attached, which are undivided and have their insertions in two comma-shaped deep inpressions near the labial process. The slender protrac- tors, attached between them, but lower down, fig. 93, are in- serted at the base of the marginal tuberosity, fig. 88. Five pairs of muscles, that, without doubt, exist in all, were first observed in this species, m. phar., fig. 86. Omne of each pair is attached to either side of the labial process, and inserted on the pharynx. Their action must be to expand it. The two »linee&e eminentes» of the dental slide, Pl. X, fig. 135, 137, are contiguous, linear, placed at less than a right angle to each other. The teeth are long, high, compressed, the 5 the largest, then the 1 and 4, the 2 and 3 being smaller. They are slightly curved inward. Their back, of a triangular section, fig. 138, expanded and wedge-shaped at the crown, fig. 151,is received into the corresponding furrow of the slide, fig. 135, 136. the roughened area for the fibrous tissue being linear, fig. 137.
68 SVEN LOVÉN, ECHINOLOGICA.
In the Laganum decagonale Biyv., Pl. IX, fig. 94—101, Pl. X, fig. 139, Pl. XT, fig. 143, 152, the dental system is high, pen- tagonal, the rays very short, the sides bemg only feebly reen- tering, symmetrically unequal, the 5 being to the 1 and 4 as 1 :Oy74, (to sthe 2,and, 3: as .1,:0;7a. The sambriusyförmed Roy the five strong alveolar crests, fig. 143, is conformable, pen- tagonal, the wings Za 5b and 5a 4b but slightly extended on the rays I and V.
The dental slide, fig. 94, 98, is a very little concave, al- most straight, recumbent at an angle of about 37”. The area of the symphysis, fig. 98, is broadly lunate, the external out- line being regularly arcuated. The pyramid seen from above, fig. 95, is, like that of the preceding, arrow-headed, its crest is very strong, transverse, with the tuberosities doubled. The lamellated inner wing is raised and adjoins the crest with a depression but without any interjacent lacune. The epiphysis is high, a simple lamella, fig. 94, 95, 100. 'There is no ro- tula. The under surface, fiy 96, 97, unconformable, is not level, but strongly bulging, the middle compact part convex, externally inflected, the tuber simple, the mesial ridge di- stinct; the lamellated borders rising, much expanded, rounded, a large lacune separating them from the crest. The pyramid 5, fig. 97, 143, is large and equilateral, the 1 and 4, fig. 96, 143, smaller, inequilateral, the a side of the 1, and the b side of the 4, both contiguous to the 5,/ expanded and rounded; the 2 and 3 have their contiguous sides larger. 'Phe labial process is inflected, broad. The lateral sheets, fig. 94, 98, 99, are broadly obovate, slightly emarginated for the epiphysis, the curves of acceretion distinct, the radiating ridges slight and few, without perforations. The rachis, which is not marked with holes, coimcides with the outer limit line of the triangu- lar area, tr., which is compact and divides the whole into a larger lower area and a smaller upper, fig. 94, 99. When the intermuscular sheet is removed, fig. 99, the radiating ramified lamellate partitions are seen to issue from either side of the tr. The imner wing, about half as large as the outer, has its radiating lamels regular, not intercepted by any lacunes. The auricles, fig. 101, like those of Encope, arise from the interradium; they are united into one single piece for each tooth, flattened con- centrically, thin, narrow below, then expanded, slightly lobated. Along their margins the two strong bipartite retractors are
BIHANG TILL K. SV. VET.-AKAD: HANDL. BAND 18. AFD. IV. N:0O1. 69
attached. They have their insertions in two pairs of linear, walled impressions, one on either side of the basilar ridge, fig. 96, 97. Near the top of the auricle are attached the two slender protractors, inserted in a line with them, near Field cunes:u) Lhetsteeth, Lri. LX: fig. 94, PUNXN I figiIS9) Pl XI, fig. 152, unlike those of the preceding, low, thick, slightly curved outward, like those of Clypeaster or Echinocyamus, the 5 much the larger, then the 2 and 3, the 1 and 4 being smaller. 'The back, expanded and wedge-like at the crown, is of a triangular section and received in the deeply triangular dental slide. The prismal part is very low and broad, of a nearly rectangular section.
In the Echinocyamus angulosus LEsKE, Pl. IX, fig. 102 — 109, Pl. XI, fig. 141, 145, the dental system is high, pul- vinate, pentagonal, the 5 broad, transverse, the III a little pro- duced. The sides are symmetrically and bilaterally unequal, the 5 being to the 2 and 3 as 1 to 0,77, and to the 1 and 4, as to 0,70. The 5, fig. 105, 141, is transverse, broader than it is long, the 4, fig. 104, much narrower, but equal in height, the b-side larger. The alveolar ambitus is conformable, pen- tagonal, the I and V slightly produced beyond its corners. The dental slide is raised, reclining at an angle of nearly 50”, slightly concave. 'The symphysis is lunate, convex, but not bulging exteriorly. The pyramid 4, fig. 103, seen from above, is arrow-shaped, the crests strong, the supra-alveolar process large and prominent, fig. 102, 104, 105, 106. "The epiphysis and rotula, fig. 103, 108, are simple lamine. The inner wings are convergent, not lamellated, fig. 147, the dental slide deep. The inferior surface is as in Laganum, convex, strongly arched, the middle compact part narrow, the sides much expanded, rounded, rising, not lamellated, but the reticular texture evi- dently radiating, fig. 104 Xx, 105, 107 Xx, 141; they are sepa- rated from the crest + not by a lacune, but only by an oval transverse impression. The 1 and 4, and 2 and 3 are inequi- lateral, as in Laganum. The labial process is broad, projec- ting. The lateral surfaces, the inter-muscular sheets, fig. 102, are obovate in the direction of the tr., truncated above for the epiphysis, with distinct curves of aceretion, but no radiating ridges and no perforations. The triangular area, tr., is broad above, for the large supra-alveolar process, and compact. The outer wing is broadly lunate, the inner short. The au-
70 SVEN LOVÉN, ECHINOLOGICA.
ricles arise from the interradium. They are united into one piece, broadly expanded at the base, faintly bilobated, fig. 109. The retractors are bipartite, attached to the auricle near its margin, slightly descending adorally, and inserted rather low on either side of the mesial ridge. The slender protractors are attached between the lower parts of the retractors and inserted a little above the middle of the under surface. The teeth, Pl. IX, fig. 102, Pl XI fig) 141, 145; long) low, ShEmv curved outward, are more erect and capable of being protruded than in the other genera. "Their backs, of a triangular sec- tion, are received in the deep groove of the slide, their prismal part being slightly more compressed than in the Laganum.
Among the leading forms of the Odontophora Irregularia here reviewed with respect to their maxillary system, the Echinocyamus has more of the Regularian type than any other. "The height of the whole system; the nearly erect po- sition of the teeth. which are low and curved outward; the form of the external surface of the pyramid, cordate, not ar- row-headed, fig. 104, 105, and the simply lunate symphysis recalling the Discoidea; the epiphysis, simplified in form but still proportionally of conspicuous size; the nearly compact, not lamellar nor lacunal structure of the wings, the two interior of which are slightly converging, all this, combined with the unin- terrupted sequence of the uniform interradia, which are half as broad as the likewise uniform ambulacra, but not compressed; the pedicellar pores confined to the ambulacra, not spreading upon the interradia;! the internal peritoneal layer forming on every interradium two simple partitions like those of the Galerites —, all this constitutes in the Echinocyamus an assem- blage of approximations towards the Regularia, archeeonomous features not inconsistent with the alleged but not fully con- firmed early appearance of the genus, earliest of the whole tribe as far as at present known, in the cretaceous strata at Maestricht.? In these strata the genus Fibularia is also said to be represented;? it is very similar to Echinocyamus, but has the lamellar structure of the wings fully developed.?
Near to these two forms comes the genus Laganum, with the teeth low, slightly curved outward, raised at an angle of
! Études s. 1. Echinoidées, p. 32, 47, P1. XLIV. ? E. placenta GLDpF, DEsor,. Synopsis p. 220. 3 Fibularia subglobosa GLDF., ib. p. 221.
-
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:o1. 71
30” to 40”, the 2 and 3 larger than the 1 and 4, the absence of any lacune on the upper alveolar side; the same broadly curvate form of the external side of the pyramid; the broadly lunate symphysis; the epiphysis not much reduced; and the sequence of the five compressed but very nearly uniform in- terradia uninterrupted. But the lamellate texture of the wings is fully developed.
Another group is here represented by the genera Echin- arachnius and Encope. They have the whole system low, the teeth, of which the 1 and 4 surpass the 2 and 3, long, high and compressed, curved inward, reclining at an angle of 10” to 15”; the symphysis not lunate but broadening adorally, the epiphysis diminished, the arrow-shaped form developed; the wings highly lamellated and lacunal. The ambulacra are nearly uniform; in the young animal they give free space to the continuous sequence of the interradia, but in the adult interrupt them more or less in the trivium, while the se- quence of the 5 is retained.
In these two groups the first plate of every interradium maintains its place in the adult, and bears the auricle, the branches of which are coalesed into one piece.
The genus Arachnoides stands alone. The whole system is low and signally stellate. The teeth, of which the 2 and 3 surpass the 1 and 4 in size, are high, almost straight or slightly curved inward, reclining at an angle of 16”; the pyramid is exquisitely arrow-shaped; the symphysis is ex- panded sublabially, but much more so above and outward, forming a hump; the forked crest renders the alveolar ambi- tus unconformable; the rotula is elaborate; the outer wing is produced, lanceolate; the inner wing very short. The auricles rise from the ambulacrum with separate branches. All this, combined with the great preponderance of the ambulacra, even to suppressing the first plate of the four interradia and ex- cluding that of the 5 from the peristome, gives the genus a highly neonomous character.
With the Arachnoides, its orbicular and depressed test and flat ventral surface, and the eminently stellate form of its dental system, the genus Clypeaster contrasts by its oblong test, its pen- tagonal system, by the peristomal region being strongly drawn in into the ventral surface at an angle of 45”, by the position and form of the teeth. But it agrees with Arachnoides in its
(20 SVEN LOVÉN, ECHINOLOGICA.
auricles rising from the ambulacra, in the prolongation of the outer wing of the pyramid and the figure of the symphysis area, in the greatly developed hump of the corpus, and in the position and number of the spheeridia. With Encope and Echi- narachnius it accords in the disposition of its ambulacra which interrupt the sequence of the interradials and give place in the peristome only to a diminutive first plate, and with the Echi- nocyamus in the nearly vertical position of the outward cur- ved teeth — but not in their form, — in the shape of the test and the pentagonal figure of the whole maxillary system. But from them all it differs by the fosse and by the form of the alveolar ambitus.
Important characters common to all the forms of the tribe indicate a mode of living very different from that of the Odon- tophora Regularia. By the more or less flattened form of the test its ventral half-part is brought into ample and con- stant contact with the ground along which it is dragged by minute but very numerous pedicels and dense but short and slender spines. The peristome of the young persists in the adult unaltered in composition, the solitary first interradial plate retains its place, and the primary first plates of the ambu- laera, not detached from their columns, remain as parts of the final torona, each with its characteristic pore and large pedicel. Accordingly the membrane that within the stoma surrounds the oral aperture, is labial, and presents no trace of reabsorbed ambulacral plates. The dental system offers great peculiarity: the bilaterally disposed pyramids, of which the axial 5 always is larger and higher; the total absence of the musculi radiales; the all but universal reduction of the rotula, the rudimentary condition of the epiphyses which in the Re- gularia play so essential a part in supporting the strain ex- erted by the retractors; the teeth feebly and variously arcua- ted, more or less reclining, bilaterally convergent, the axial 5 stronger, with the upper angle of its crown nearly right, the front pair, 2 and 3, working upon it, with their upper angle obtuse, the adoral angle more acute, the 1 and 4 intervening from the sides. The whole is evidently adapted to movements of no greatj vertical "amount and essentially horizontal, go- verned by muscles comparatively of no great strength, — inter- pyramidal muscles whose mode of attachment does not point to a habitual straining of their fibres; retractors, rather strong,
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:o1. 73
with the opposite points of attachment and insertion nearly on a level, and thus almost parallel with the ventral surface of the test; the protractors vertical but weak, generally not ca- pable of protruding the teeth far beyond the level of the small stoma, but well adapted to bringingtogether and to rub against one another their crowns and thus within the fixed peri- stome to grind the food substances introduced into the pha- rynx. Thus it seems that further researches will tend to exhi- bit, among the Odontophore, the Regularia as predacious and perhaps mainly carnivorous animals, the Irregularia in some sort as omnivorous.
I nm-pro. Mm.re. Vd
The position of the auricles in different types of Echinoidea. 1. Tripneustes. 2. Clypeaster. 3. Arachnoides. 4. Encope. 5. Echinocyamus. z 6. Cidaris.
In concluding these remarks I have great pleasure in ex- pressing my obligation to Mr GEorRGE LILJEVALL for the assi- duous care he has taken to elucidate them with his truthful pencil, and for the highly valuable assistance I have received from his keen eye and nice perception, and from his lively interest in my endeavours to throw some light on points of Echinoidean morphology hitherto not much studied.
Al: ext., Al. int.,
Avur., Camn., Cond., Corp., (Öl JBX- Ep., HO:
Gl. Int., Lam. int
M. int. M. phar., M. pro. M. re;
M. ro. e.
Os.,
Pe. buc., Er: 00: Pr, sup, Eh., 00... Sept., Sph.,
IS. de.,
Su. med.,
Symplh., Tr. PUNG
Abbreviations.
the external wing in the Clypeastride.
the inner wing of the lateral inter-muscular sheet, separated by the triangle, tr., from the al. ext.
an auricle or its branch.
the central canal in the alveole.
the condyloid eminence of the rotula.
corpus, the compact middle body of the pyramid in the Clypeastride. the supra-alveolar crest.
the tooth.
the epiphysis.
the fossa of the pyramid in Clypeaster. The fossa of the rotula in the Regularia.
the glenoidal cavity of the epiphysis.
the intestine.
. the lateral sheet of the pyramid, to which the inter-pyramidal muscles are attached.
the inter-pyramidal muscles.
the external muscles of the pharynx.
the protractor muscles of the pyramid.
the retractor muscles of the pyramid.
and m. ro. i., the external and internal rotular muscles, fig. 42, 44, 45, 46.
the mouth.
the buccal pedicels.
the labial process.
the supra-alveolar process.
the rachis.
the rotula.
the septum between the fosse in Clypeaster.
a spherid, fig. 80, 56.
sulcus dentalis, the dental slide.
the mesial suture of the pyramid.
the syvmphysis of the half-pyramids.
the triangular area that separates the wings in the Clypeastride. nd tu. e., the tubercles, internal and external of the epiphysis, fig. 42, 49, 51.
PAD ST.
Figures 1 and 2.
1. Gomocidaris canaliculata AL. AG. Young specimen, in spirits, side view, the large provisional suckers extended.
2. Another young specimen, in spirits, from above, showing the calyx with the dorso-central disk well defined. The provisional suckers contracted.
Bihang till K. Sv. Vet. Akad. Handl. Bd.18, Afd. TV, NM I. BIE
Fig. 1
G. Liljevall del. Ljustryck af C. Westphal, Stockholm.
ETRATYR TT: Figures 3 to 9.
Fig. 3. Goniocidaris canaliculata. AL. AG. Dorsal view of another specimen.
Fig. 4. The radial III of the same, with the provisional sucker extended from under its adoral margin.
Fig. 5. Dorsal view of another specimen, with the dorso-central disk.
Fig. 6. The dorso-central disk, a thin lamina of calceified tissue, the soft substance being removed.
Fig. 7. Dorsal view of another specimen, 1,45 mm. in diameter, dried.
Fig. 3. Side view of the same, seen from the ambulacrum II.
Fig. 9. Ventral view of the same, showing the inner circle of the five pairs of primary ambulacral plates and the second of five large, solitary interradials and five pairs of fixed ambulacrals.
Billang till K. Sv. Vet. Akad. Handl. Bd.18, Afd. TV; Vv: 1 BIS
rig. 7 RR ML 7
Ljustryck af C. Westphal, Stockholm
GG. Liljevall del.
PIA NE EE.
Figures 10 to 24.
10.
l; 12.
19:
. 20:
Goniocidaris canaliculata AL. AG. Same specimen as Pl. II, fig. 3, opened so as to show the intestine, seen from above, a the anterior, p the posterior termination of the intestine; = the rectum, the aqui- ferous canal. the ovoid gland and the blood lacunes in connexion. The same, side view.
The same, ventral view of the intestine. The six lines refer to the
. 13—18. Six vertical sections through the intestine, and fig. 15 through
the oesophagus, fig. 17 through the rectum.
Another specimen, decalcified, seen from above. Horizontal section showing the test with spines, pedicels, ambulacral vessels and the intestine. The plane of the section is somewhat slanting, from TIIT, where it cuts the uppermost ambulacrals, to about IT, falling in there with the third pore from the radial. a is the anterior termina- tion of the intestine, oes. the oesophagus; p its posterior termina- tion, near the anterior end the aquiferous canal, the ovoid gland, and the blood lacunes are seen cut through.
Another horizontal section. Both ends of the intestine; oes. the esophagus.
The innermost layer of the costal 2 with the water-pore; ». the rec- tum, int. the intestine; cal. part of the calyx.
The same specimen as fig. 10. Inside view of peristomals I, 5 and V, showing the two half-pyramids of 5 with the tooth and the mus- cles, m. re. and m. pro. attached to the solitary peristomal 5, the beginnings of the epiphyses, ep., and of the rotule, ro.
Side view of the dental apparatus of another specimen with the rai- sed half-pyramids beginning to enclose the tooth.
Horizontal section, tinctured with borax carmine, of the two half- pyramids and the tooth, d.; me. the enveloping membrane.
l
7 Av. Ce. for. I.
> RESET SSA ER
G. Liijevrall det. Ljustryck af C. Westpbal, Stockholm.
BRATE:
Figures 2925 to 28.
Fig. 2
Strongylocentrus drcäebakensis O. F. M. Young specimen, of 1,2 mm., from spirits in Canada balsam, ventral half seen from the outside. The primary ambulacral plates I, V, IV b, drawn as if transparent. The peristome beginning to be- eroded, the solitary first plates of the interradia remaining for a great part intact. The primary ambulacrals still close to their columns.
The same specimen, ventral portion, seen from within. The au- ricles beginning to form under the retractor muscles.
The same specimen, dorsal half viewed from the outside. The dorso- central disk still for a great part retains its original pentagonal shape.
Another specimen, 2,2 mm. in diameter. The mouth opened. The primary ambulacrals, heterotropic, still close to their columns; the peristome slightly more eroded than in fig. 25, a lesser part of the solitary first interradials remaining; the gills have appeared.
Bihang tl Ko Sv. Vet. Arkad. Handl.-Bd.18;, Afd.IV, ARI. PIEARV Ag TES Fig.25 rn
Ljustryck af C. Westphal, Stockholm
GG. Liljevall del.
CAT SE LL Blok bart SA
PLATE V. Figures 29 to 38.
Fig.
20.
Echinus miliaris LESKE, a young astomous specimen, 2,5 mm. in diameter, denuded and dried; ventral aspect. The stoma is covered all over with the larval envelope, within which the teeth are seen protruding. The ten pairs of primary ambulacral plates free from the corona, encircling the future mouth. The peristome eroded. The buccal membrane with large flakes of calcified tissue. The gills formed. The position of the ambulacral pores heterotropic.
Inside view of a part of the peristome seen obliquely, from above and from the ambulacre IV, so as to show the rotule, the compasses, the radial muscles, and the epiphyses. The auricles are rising on the ambulacra.
Two auricular branches, more magnified, to show the sutures marking their bases.
Diagrammatic section of the stoma showing the central conical pro- trusion caused by the teeth, the primary pedicels, and the gills.
A gill, in dried state.
The specimen fig. 29, in dorsal aspect, aproctic. The epistrome, on the corona spread around the verruce, is highly developed on the costals and radials of the calyx, but absent on the dorso-central disk, which is thinning off, but still is entire though rounded.
35—98. NSpinary verruc&e breaking through the epistroma.
Bihang till K. Sv. Vet. Akad. Handl: Bd.IS, Afd: CV, NET. PEN
Fig.29 a I 3 ip Ka &
Fig.35
G. Liljevall del Ljustryck af C. Westphal, Stockholm.
PISATE VI.
Figures 39 to 51.
Fig. é
Fig.
Fig.
40.
41.
ig. 42.
. 43.
2 DI
Cidaris papillata LEsKkeE. The pyramid 5 with its muscles, from above, showing the upper surface of the epiphyses, the compass, and the m. radiales. On the auricular branch a the m. protractor and m. retractor are both preserved; on the b the m. re. is exposed, the m. pro. being removed.
The peristomal part of the interradium 5, seen from the stoma. On b both muscles are cut away, their attachments left. On a both muscles are in situ, entire, with their lines of insertion in the sub- marginal groove of the pyramid.
The pyramid 5 from without, the auricular branches being removed. On the a the m. pro. is entire, the m. re. is removed save its in- sertion; on the Db the insertion only is left of the m. pro., while the m. re. is entire.
The half-pyramid 5 a, side-view. The m. re. and m. pro. both in situ. The articulation of the epiphysis: the glenoidal fossa, gl., for the condyloid prominence, cond. fig. 44; the interior and exterior tubercles tu. i., tu. e, for the fo. i. and fo. e, and the rotular mus- cles, m. rot. i. and m. rot. e.
The half-pyramid 5 a from the side. both muscles in situ, the ten- dinous part of the m. re. in view.
A rotula from the under side, the inner end in front; letters as in fig. 42.
Section of rotula and epiphysis with »m. ro. 4.
Section of the same with m. ro e.
Echinometra Lucwnter L. The dental apparatus seen from the interradium 5. The broad and linear protractors arising from it, the retractors from auricular branches I a and V Db.
The motor muscles seen from the interior, the pyramids being re- moved; the m. pro. entire, showing their insertion on the upper part of the pyramid 5; the two m. re. of the 5 from I a and V b; the re I b removed, the V a, belonging to the pyramid 4 b, entire.
The epiphysis with the articulation and the m. rotulares. Asthenosoma varium GruBE. The dental apparatus seen from the interior. The tender auricies, which give attachment to the retrac- tors, supported by the flexible ambulacrum, are stayed by means of muscles from the »longitudinal muscles», and others from the buccal membrane.
The epiphysis, with the articulation and the m. rotulares.
Bilang till K. Sv. Vet: Akad. Handl. Bd.18, Afd. TV, MI. SAVA
2-pro. I Fig. 49 FR
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ip SVG
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Ljustryck af C. Westphal, Stockholm.
GG. Liljevall del.
PLATE VII.
Figures 52 to 64.
. "9 « DA.
-
Clypeaster reticulatus L. The half-pyramid 5 b seen from the am- bulacral side, cut vertically in the direction of the line B, fig. 58, and partly fractured so as to lay open the fossa, the alveolar cavity and the dental groove. The tooth is represented as if transparent. The same, the auricle being removed, to show the muscles, X the attachment line of the m. re. 1.
Part of the same seen from the interradial side, the pyramid being removed.
The auricular branches V b and I a seen from above; X as in fig. 59. Vertical section along the line A fig. 52, seen interradially from the interior, in the direction of the arrow.
The pyramid 4 from its upper side, denuded.
The pyramid 5 from its under side.
The pyramid 5 a, lateral view of the inter-pyramidal surface of the wing.
The half-pyramid 4 a, from the side of the symphysis; the tooth drawn as if transparent.
The mouth with the ends of the five teeth.
A rotula, side view.
Echinometra Lucwnter L. A pyramid with the epiphysis seen laterally. :
The same from the external side.
Bihane till K. Sv. Vet. Akad. Handl. Bd.15, Afd. IV, Md. PISSVI
pr Sup.
re 2
A MT
<< DN am
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3 lam.int. Väne — pr sup.
G. Liljevall del. Ljustryck af C. Westphal, Stockholm.
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PLATE VII. Figures 65 to S5.
> LILL Fr
4 bökar. a SUM fen ; Nn SLET mån NA
Kar
Fig.
Fig.
65.
66.
Clypeaster reticulatus L. Adoral part of the pyramid seen late- rally, the sheet which serves for the attachment of the inter-pyra- midal musecles being removed in order to show the regular final ra- mifications of the lamels, their irregularity at the triangular area, and in the very short interior wing. Compare P1. VII, fig. 52, 59. Half-pyramid, vertical section rectangular to the symphysis, at about !/, from the dental slide, showing the compact corpus, the lamels and the rachis.
The texture at X fig. 66, magnified.
Part of the same more magnified.
The reticulated texture of a lamel, seen from its side, the rods pa- rallel to its upper margin.
Section in the line A B fig. 66, seen from above.
Part of a lamel with its final ramifications, seen sidewise obliquely and somewhat from behind.
A branchlet, by means of its ultimate ramification forming the inter- muscular sheet.
Arachnoides Placenta L. The dental system, side view, the pyra- mids 3 and 4, and the greater part of the 5 a being removed. From a dried specimen.
The half-pyramid 4 a to show the form of the symphysis, the al- veolar cavity, the rhachis. The tooth is drawn as if transparent The pyramid 4, dorsal aspect.
The pyramid 5, ventral aspect.
A rotula.
The mouth with the ends of the teeth. k Arachnoides Zelandie Gray. Adoral part of a pyramid seen late- rally, the inter-muscular sheet being removed.
Encope emarginata LEsKE. The dental system, side view, the pyramids 3 and 4 with the greater part of the 5 a having been removed.
The pyramid 4, dorsal aspect.
The pyramid 5, ventral aspect.
The half-pyramid 4 a, showing the area of the symphysis, the al- veole, the supra-alveolar process. The tooth drawn as if transparent. Side view of the halfpyramid 3 a, the intermuscular sheet being removed.
A rotula.
BIetUIEKOSY Vet kad. fandiBi18) Afd: IV, Ne. ARN
scr GOr
vv UUV Uv
55008 300
ta 3 Ove lamint
Pr Sup.
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G. Liljevall del. Ljustryck af C. Westphal, Stockhol:
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Fig.
386.
ST. 35. 59.
J0.
SSI SET
SE
94.
Echinarachwius Parma LaAMmcK. The dental system, side view, the pyramids 3 and 4, and the greater part of the 5 a being removed. The mouth and pharynx and the oesophagus cut through, showing the bands by which the pharynx is suspended, and the pharyngeal muscles.
The pyramid 4, dorsal view.
The pyramid 5, ventral view.
The half-pyramid 4 a, alveolar view, the tooth drawn as if trans- parent.
The half-pyramid 3 a, lateral view, the inter-muscular sheet being removed to show the lamels and the triangular area.
The rotule I and III.
Part of the peristome, amb. II, I and V, interradia 2, 1, 5, with the auricles and the external motor muscles.
Laganuwm decagonale Bry. The dental system, side view, the pyramids 3 and 4 and the greater part of the 5 having been re- moved. The mouth cavity, the pharynx and the oesophagus cut through.
The pyramid 4, dorsal view.
The same pyramid, ventral view.
The pyramid 5, ventral view.
The half-pyramid 4 a, alveolar view, the tooth drawn as if trans- parent.
The half-pyramid 3 a, the inter-muscular sheet removed to show the lamels and the triangular area.
The processus supra-alveolaris with the epiphyses and no rotula. Part of the peristome, inside view, as above fig. 93. Echinocyamus angulosus LEsKkKE. The dental system, side view, the pyramids 3 and 4 and the greater part of the 5 a being re- moved.
The pyramid 4 upper surface.
The same, lower surface; + and X referring to fig. 107.
The pyramid 5, lower surface.
The half-pyramid 4 a, alveolar view.
Part of the outer wings, upper side, + and X referring to fig. 104. A rotula.
Part of the peristome, internal view, as above, fig. 93, 101.
Bilaneg till K. Sv. Vet. Akad. Handl. Bd.18, Afd. TV, .v2 1. PIC Fig.I3 270.
”p ro.
mreå
Ljustryck af C. Westphal, Stockholm.
G. Liljevall del
Å 0 Pest) "ert
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ig. 135.
Fig.
Fig. Fig. Fig.
4 10:
SORT & 12: Ber >, 114: ig. 115. Sn all Ae 0 INGE ig. 119. ig. 120. ig. 121. ig. 122. IT : 124, 125:
. 126. 127 ig. 128. ig. 129. H30
LTS . 182. g. 183.
g. 134.
136.
137. 138. 139.
Cidaris papillata LesKeE, Section of a pyramid with its tooth; in this and following figures X the rough area and + the fibrous tissue. The dental slide with the two »line& eminentes» VAL.
A tooth, side-view.
The half of the alveolar cavity.
Discoidea cylindrica, LamecKk. The dental slide.
The halt of the alveolar cavity.
Asthenosoma varium, GRUBE. Section of a pyramid with its tooth. Tooth seen from the side and from behind.
The half of the alveolar cavity.
Diadema saxatile, L. Section of a pyramid with its tooth. Echinus esculentus, L. Section of a pyramid with its tooth.
A tooth, side-view.
The half of the alveolar cavity.
The dental slide.
A tooth, back view.
Section of a part of the pyramid at X and of the tooth, to show the fibrous tissue + that connects them.
The structure of the rough area, magnified.
The same, longitudinal section.
The same, transverse section.
The symphysis of the pyramid.
Strongylocentrus lUvidus LameK. Section of a pyramid with its tooth.
Clypeaster reticulatus L. Section of a pyramid with its tooth. The dental slide; X the rough area.
The tooth, back view; X the rough area.
Section of a part of the pyramid and of the tooth showing the extension of the rough area X and the fibrous tissue +. Echinarachnius parma, LAMcK. Section of a pyramid with its tooth. The mesial suture is serrated; XX the compacted tissue ending in the »triangle>. ;
Section showing the extension of the fibrous tissue and the mesial suture; X and + as above.
The dental slide.
ÅA tooth, back view area.
Laganum decagonale, Brv. Section of a pyramid with its tooth.
Bihang till K. Sv. Vet. Akad. Handl. Bd.18, Afd. TV, .V 1. ENA / Fig113 Fig. a 2 a Fig.112
[0] frO oe DH Oo (2)
G. Liljevasll del. Ljustryck af C. Westphal, Etockholwmw
SV dena TT TEEN Bab tetsire h Mek Er Lan JNA vänn Qujlanas
sp per och km URL
. 140.
Echinus nmiliaris LEsKE. Section of the dental system, showing the five pyramids with their teeth and the inter-pyramidal muscles. Echinocyamus angulosus LEsKE. Section of the dental system, the five pyramids with the teeth and the inter-pyramidal muscles. Echinarachnius Parma LaAmcK. Section like the preceding. Lagamwm decagonale Brv. The dental system, entire, seen from above.
Clhypeaster reticulatus L. The same.
Echinocyanvus angulosus LEsKE. The same.
Araclhmoides Placenta L. The same.
Echinaraclwvius Parma. LaAmcK. The same.
Encope emarginata LEsSKE. The same.
Clypeaster reticulatus L. Crowns of the five teeth, front view. Clypeaster reticulatus L. Crown of a tooth seen sidewise. Echinarachnius Parma LAMcK. OCrowns of the five teeth, front view.
Laganwm decagonale BLv, the same.
Bihang tul K. Sv. Vet. Akad. Handl. Bd.18, Afd. TV, .M I. PIC:
Fig. 141
ur
Fig.145 Pig.143
Fig. 152
G. Liljevall del Ljustryck af C. Westphal, Stockholm.
PEATH XI Figures 153 to 166.
Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig.
Fig. Fig.
Fig. Fig. Fig.
153. 154. 155. 156. 157. 158. 159. 160. 161.
162. 163.
164. 165. 166.
Diadema saxatile L. Part of the buccal membrane. Centrostephanus coronatus AL. AG., the same.
Aspidodiadema Antillarum AL. AG The whole buccal membrane. Echinus esculentus L. Part of the buccal membrane. Echinometra Mathei Buv. The same.
Lytechinus semituberculatus VAL. The same.
Echinocidaris nigra. Mor. The same.
Salenia Pattersomi. AL. AG. The same.
Asthenosoma varium. GRUBE. Part of the ventral region. The lighter lines denote the overlapped portions of the plates.
The pore of the 3" from the lip.
A the pore of the 8" plate detached into the buccal membrane, with the next, B, still fixed.
The same of the 24" plate.
The pore of the entire plate in V b, the 92" from the lip.
The same of the demi-plate 93.
Bilange till K. Sv. Vet. Akad. Handl. BOSSE Ad TNE Sven PISA
a Qt Sy NDS Fig. 157
Fig. 165
G. Liljevall del Ljustryck af C. Westphal, Stockholm.
BIHANG TILL K. SVENSKA VET.-ARAD. HANDLINGAR. Band 18. Afd IV. N:o 2.
ICHTHYOLOGISCHE NOTIZEN
VON
EINAR LÖNNBERG.
IE
MITGETHEILT DEN 10 FEBRUAR 1892 DURCH Fk. A. SMITT.
STOCKHOLM 1893. OKTRYCKERIET. P. A. NORSTEDT & SÖNER.
VASTTON THIGIHOJO1 rH ANV ATA KÖL HATE | "I SN ad to rv Vd: RER Vr MS ku
vägt (sense
säte Åå TTO AR
Uber die Variabilität bei Petromyzon.
Die Charaktere, die unsere beiden Petromyzonarten von einander unterscheiden, scheinen bisweilen schwankend zu sein. Um diese Sache näher aufzuklären habe ich bei Elfkarleö, wo eine Unmenge von Petromyzon fluviatilis gefangen wird, eine Serie von Messungen vorgenommen, deren Resultat ich hier vorlegen möchte. Wie bekannt wird angenommen dass bei Petro- myzon fuviatilis die beiden Rickenflossen von eimander voll- ständig getrennt sind. Misst man den Abstand zwischen den Räckenflossen, so muss, wenn keine Variationen stattfinden, das Verhältniss zwischen diesem Mass und der ganzen Körperlänge bei gleichgrossen Individuen gleichgross und konstant sein. Bei jängeren (kleineren) oder älteren (grösseren) Exemplaren wieder könnte sich die Sache verschieden verhalten, je nachdem der Abstand mit dem zunehmenden Alter grösser oder kleiner wurde, im letzten Falle durch den Zuwachs der Flossen, im vorigen durch die Zunahme .des Zwischenraumes ohne eine Ver- längerung der Flossen. Die erwähnte Zahl, die das Verhältniss zwischen Körperlänge und Flossenabstand ausdräckt, zeigt uns indessen das Gesetz der Veränderungen oder die Variationen, auch wenn sie nicht gesetzmässig sind.
Hier folgt das Resultat der Messungen:
ÖS Ä HAS = | SS ÅA HSE DO. &S =S Stolar AROR aa FÖ SE O: BE FaR SA SEN ro: HOS Herr 2383 DE Sa =E FT = ch S BYN fe =) His CR NN S Fe = TB cm = Fo EEE OO mA —] —- ES RIE SS --sc PP IE me AR NES = > Ef MM 25 HR = ce 5 | = DARE $ EA NE Sr od sc 0 -——N F&S = | kol He- max? PO 0-0 SN 3 mm I8 c BoES BE Sö N sm OK SISTA SNES FINGER FORN NR SNES SE 0 za P8 KR 200 SÅ CIN Da SD 2 EAfes TS GE z ER TT 2a | A-s 5 & E | = SR ms KH ee sr Se | = Or oe SI a & RJ = oc 4 2 I = 2: os 3 | vw = —E: Boss ce SES SER oe OEM cr 3 be na E N 5 5 S&S = | ö ole =7e" | SL Yr Säe | || I I - | 2 Q | - € 245 | 1 18.8 i 250 12) 19.2 245 | 12 20.4 | 255 10 ÖS z z | | 250 12 20.8 II 205 1 200 | 3 då | - I 250 || HR 25.0 | 255 15 Lö0A ou
TSG
EINAR LÖNNBERG, ICHTHYOLOGISCHE NOTIZEN.
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BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:O0 2. 5)
I = SR Å é Se spel vERSE B$Tel sit rie 2 08 FÅ SE =E 03 - SÄS | 2 EN ESR EN a EA SLE FREGE sög |AgfR|fsasr) fos |Astea a PP ek BOR. CR - a GF IR BEA I SA 2 22 SE TEE mv ae 20 | or EJ a a KR ER ES Ge SN cs I. Ö > + I & I I | | | 305 dl ant Sd fär | d825 12 Gr 305 re Ng fia I ROR 12 27.0 305 16 19.0 350 15 22.0 305 15 20.3 330 3 25.3 305 9 30.8 330 3 25.3 | 305 10 30.5 330 | 12 NES 305 11 MR 3304 15 22.0 | 305 14 21.7 3801 | 13 25.3 310 adl 28.1 330 | 9 36.6 310 15 20.6 335 | 15 22.3 310 12 25.8 335 14 23.9 310 9 34.4 330 fll 16 20.9 310 17 18.2 235 Ia | 15 22.3 315 1 18.5 SYLVAN 15 22.6 315 12 26.2 340 12 28.3 315 2 26.2 340 16 21.2 315 16 19.3 SAM Kål 19 17.0 315 16 19.3 Säby | 18 18.0 320 12 26.6 345, | 20 17.2 320 17 18.3 350 | 16 18.7 320 15 ME 350 | n (2) TEE: | 320 16 20.0 60 (Få Släng Ju | 320 12 . 26.6 365 | 17 21.4 320 12 26.6 365 | 17 21.4 320 13 25.3 370 | 7 21.8 325 12 27.0 sin PI 18.7 325 20 16.2 |
Aus dieser Tabelle geht es hervor, dass das kleinste Exemplar 245 Mm. und das grösste 375 Mm. mass. Der kleinste beobachtete Flossenabstand ist 5 Mm., der grösste aber 23 Mm. Wir finden weiter, dass weder die grössten Exemplare die grössten (oder die kleinsten) Flossenabstände haben, noch die kleinsten Exemplare die kleinsten (oder grössten) Flossenabstände. HEine sorgfältige Berechnung zeigt uns doch, dass die absolute Grösse der Flossenabstände mit dem Zuwachs der Körperlänge etwas, wenn auch nicht regelmässig, zunimmt. So ist z. B. der betreffende Abstand bei einer Körperlänge
6 EINAR LÖNNBERG, ICHTHYOLOGISCHE NOTIZEN.
280 Mm. durchschnittlich! etwa 12 Mm., bei einer 295 durchschnittlich etwa 13 Mm., bei einer Körperlänge von 300—325 Mm. etwa 15 Mm. und bei einer Körperlänge von 330—375 etwa 17 Mm. Dies ist im grossen und ganzen gesehen, aber aus der Tabelle findet man, dass innerhalb aller der angefährten Gruppen zahlreiche Abweichungen von der Regel und grosse Schwankungen äberall auftreten. Diese Variationen werden durch die Zahlen der dritten Reihe ausgedräckt. Aus diesen geht es hervor, dass die Grenzen der Variation in den hier untersuchten Fällen sich zwischen 56.0 und 12.8 befinden d. h., dass der Flossenabstand wenigstens
von 245 Körperlänge von 285
= und höchstens Te der gesammten Körperlänge beträgt. In den 141 untersuchten Fällen war der Flossenabstand 7
NG rad) TT EE Mal kärzer als 30 56.0” 30.2” 366 34.4”
1 1 . i å = RE v — dazu Zell Mal -) und zwei M Kör 58.50 B5-s und s0å la we al sv) u e al grösser
der Körperlänge (resp.:
1 i | 1 2 1 als Ta (resp. 6 1 und dazu ein Mal 53)
Vergleichen wir die relativen und absoluten Schwankungen in Betreff der Grösse des Flossenabstandes, zeigt es sich, dass ihre Maxima und Minima in ungefähr demselben Verhältnisse zu emander stehen; 23:5=4.60 undi536.0: 12.81= 4129 Fine bedeutendere absolute Grösse fällt doch nicht immer mit einer relativen zusammen.
Was ich oben Flossenabstand nannte, ist der Abstand zwischen den wirklichen, ausgebildeten Rickenflossen, da aber die hintere von diesen vorne nicht scharf begrenzt ist, sondern sich in einen Hautkamm oder bisweilen nur in einen niedrigen Grat fortsetzt, wird die Sache noch mehr kompliziert. Der erwähnte Hautkamm ist nämlich bald kaum sichtbar oder nur sehr schwach entwickelt, bald ist sie von beträchtlicher Länge? aber so niedrig, dass sie nur von oben wahrzunehmen ist, in anderen Fällen wieder bekommt sie auch eine gewisse Höhe. In keinem von mir beobachteten Falle war doch der betreffende Hautkamm zugleich hoch und so lang, dass er die Flossen mit einander verband. Solche Hautkämme bilden natärlich den fylogenetischen Ursprung der Flossen und da sie fortwährend
! d. h. das arithmetische Medium des betreffenden Abstandes. 2? Sie kann sich bisweilen beinahe bis zur vorderen Riäckenflosse aus- dehifen.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:02. 7
die Potentialität sich zu Flossen zu entwickeln besitzen, ist auch ihre Variation von gewisser Bedeutung.
Da ich die Variation beim Petromyzon fluviatilis in Bezug auf die Ausdehnung der Räöckenflossen gefunden hatte, wurde es mir angelegen auch eine grössere Zahl von Petromyzon Planeri zu untersuchen, weil die Variation der ersten Art eingehend ein Speciesmerkmal beriährte. Hätte nämlich auch die letzte Art auf eine entsprechende Weise variirt, sollte es kaum möglich sein die beiden Formen von einander völlig ab- zutrennen.
Bei Untersuchung einer sehr grossen Zahl von Petromyzon Planeri, teils vom Wettersee teils vom kleinen Fluss Fyris in Upsala, ergab es sich aber, dass bei dieser Art beinahe immer die Räckenflossen! einander berähren oder sogar mit einander zusammengeschmolzen sind. Nur bei einem Exemplar waren sie durch einem Zwischenraum von 4 Mm. getrennt, aber in diesem Zwischenraum dehnte sich ein hoher Hautkamm aus, der die Flossen mit einander verband. Da aber der letzte Fall den Karakter einer Ausnahme besitzt, scheinen freilich die erwachsenen Petromyzonten durch den Flossenabstand leicht in zwei Arten sich unterscheiden zu lassen. Schwerer ist es mit den Jungen und Larven. Bei ihnen sind die Flos- sen natiärlich kleiner und daher ihre Grenzen noch weniger markiert als bei den alten, es wird daher schwer zu sagen, wie gross der Zwischenraum ist und dies desto mehr, weil der erwähnte Hautkamm recht gut entwickelt ist. HEinige Messungen von Jungen, die aller Wahrscheinlichkeit nach der Art Petromyzon fluviatilis zugehörten, weil sie in solchen Fläössen gefangen sind, wovon man nur diese Art kennt, er- gaben folgende Zahlenverhältnisse:
Körperlänge in Mm. Flossenabstand in Mm. Relation:
MM 22 28.5 60 1 60
30 3 26.6 S noch nicht vollständig 3 26.6 on; entwickelt vom Ammo- > Sö
30) coetesstadium. 3.5 22.8 97 2 48.5 95 3 31.6
! Die Riickenflossen sind bei dieser Art verhältnissmässig grösser und höher. ? Die Flossen doch durch einen Hautkamm verbunden. .
8 EINAR LÖNNBERG, ICHTHYOLOGISCHE NOTIZEN.
Beim letzten, der von Elfkarleö war, dehnte sich ein Hautkamm bis auf einen halben Millimeter vorne zwischen den Flossen aus. Aus diesen Zahlen ersehen wir, dass bei den Jungen der Flossenabstand nicht nur absolut, sondern auch relativ kleiner als bei den alten ist. Ein Unterschied zwischen den Arten wird also hierdurch sehr schwer.
Im Ammocoetesstadium wird der Ubergang zwischen Flosse und Hautkamm ontogenetisch gezeigt. Man kann hier kaum die Grenze zwischen diesen beiden Gebilden ausfinden, indem vorne in jeder Flosse die zarten Strahlen noch feiner werden und allmählich nicht mehr sichtbar sind. Hiervon ergiebt es sich, dass die Entwicklung jeder Flosse von hinten nach vorne von je ihrem Entwicklungsherd schreitet!. Bei den Ammocoeteslarven, die ich untersucht habe, sind die beiden Flossenanlagen von einem niedrigen Hautkamm vollständig verbunden. Da also die ganze Strecke weit die erste Anlage und die Potentialität Flossen zu bilden vorhanden ist, sind in dieser Hinsicht die Larven der beiden Formen gleich und man sieht leicht ein, dass der grössere Abstand bei der einen Form eigentlich ein Stillstehen oder Verbleiben auf einem fräheren Standpunkte, also urspränglich eine Hemmungsbildung ist. Ob- wohl man also die leicht begreifliche Enstehungsweise versteht und durch sie auch die zahlreichen Variationen als mehr oder weniger ausgeprägte Hemmungsbildungen zu deuten vermag, glaube ich doch, dass man die beiden Petromyzonformen (flu- viatilis u. Planeri) gegenwärtig als zwei Arten betrachten muss, die doch fylogenetisch genommen ganz jung sind, und sie geben glänzende Beispiele von individuellen Variationen, wie man von spät gebildeten Arten erwarten kann. Wahrschein- lich sind sie durch verschiedene Lebensweise ausgebildet worden und zwar auf eine analoge Weise wie Salmo salar und Salmo trutta. Petromyzon fuviatilis entspricht dann dem Salmo salar und P. Planeri dem S. trutta. Das erste von diesen beiden Paaren ist mehr mariner Natur und ist durch die reich- lichere Nahrung, die ihnen die grösseren Gewässer, in denen sie den grössten Teil ihres Lebens zubringen, darbieten können, grösser geworden, und durch andere Bedingungen traten auch allmählich andere Veränderungen ein. Es ist von Interesse
! Deshalb ist auch bei den ausgewachsenen Neunaugen die hintere Grenze der Rickenflossen scharf, die vordere aber nicht.
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:02. 9
zu finden, dass auch beim Salmo salar die Flossen des hinteren ; Körperteils und zwar die Schwanzflosse eine Veränderung gelitten hat, indem sie mehr ausgeschnitten wird. Ich darf aber nicht behaupten, dass dies ein Analogon zu der verhält- nissmässig geringeren Entwicklung der Riäckenflossen bei Pe- tromyzon fuviatilis sein kann. Es scheint doch als ob in beiden Fällen eine Anpassung zu einem kräftigeren und schnel- leren Schwimmen statt fand, denn bei den Petromyzonten könnte die allzu grosse Höhe der weichen Flossen nicht vor- teilhaft sein.
Mit Salmo salar hat auch Petromyzon fluviatilis, wie ent- fernt von einander in systematischer Hinsicht sie doch stehen, einige biologische Eigentimlichkeiten gemein, wie die Gewohn- heit, die Wanderungen in die Flässe um den Laich abzulegen vollständig ohne Nahrungsaufnahme während der Wanderung vorzunehmen. Wenn man einen in unsere in die Ostsee aus- fallenden Flässe aufsteigenden Lachs! fängt und ihn secirt, wird man seimen Darm und Magen ganz leer oder nur ein wenig gelbes Schleim enthaltend finden. Der Darm der auf- steigenden Neunaugen ist auch ganz leer und zu einem dännen Strange reduziert. Bei beiden Fischarten ist also die Nahrungs- aufnahme för eine gewisse Periode abgeschlossen. Beim Lachs dauert diese Periode nicht länger als bis zum Ende der Laichzeit, nachher wandern sie oder eher treiben sie mit dem Strom hinab in die See, wo sie wieder zu fressen anfangen und stark genug werden um nochmals nach kärzerer oder längerer Zeit laichfähig zu werden, da sie wieder in die Flässe aufsteigen. Die Veränderung geht beim Neunauge noch weiter: mit der Taichzeit wird ihr Leben zu Ende gebracht, man könnte daher erwarten, dass der Darm eine weitgehendere Reduction unter- gehen wirde. Bei den von mir untersuchten Exemplaren aber; die im November gefangen worden waren, schien die Reduction eigentlich sich zu Grössenreduction zu beschränken. Das Lumen war zu einem Minimum reduzirt und durch eine längsgehende
! Wenigstens in unseren in die Ostsee ausfallenden Flässen ist es nicht möglich solche um den Laich abzulegen aufsteigenden Lachse mit Angeln zu fangen, man mag Fliegen oder kleine Fische als Köder gebrauchen. Wie es sich mit den Lachsen an unserer Westkäste und in Norwegen verhält, die sich in den Flissen auf die erwähnte Weise fangen lassen, ob sie steril sind oder nicht, kenne ich nicht, finde es aber wahrscheinlich, dass sie per analogiam während der Periode, als sie Nahrung aufnehmen, steril sind.
10 EINAR LÖNNBERG, ICHTHYOLOGISCHE NOTIZEN.
Falte hatte der Darm sich in sich selbst hineingestälpt, so dass er in einem Querschnitte beinahe solid erschien. Das Epi- thel aber war nicht zuriäckgebildet, sondern sah ganz normal aus.! Es ist doch möglich, dass der Darm sich noch während des Winters mehr reducirt, ja, es ist sogar wahrscheimlich, dass so der Fall sein muss, da die Laichzeit nicht eher als im April oder Mai eintrifft, die Fische aber schon im September bis November aufsteigen und folglich 5—7 Monate ohne Nah- rung zubringen missen.
Die Flussneunaugen steigen in grossen Massen jeden Herbst in die in die Ostsee ausfallenden Flisse des nördlichen Schwe- dens hinauf und werden dann gefangen. Vom Umeå-fluss wird erzählt, dass die Neunaugen in Sonnenschein sich bisweilen am Damme bei Baggböle ganz an der Oberfläche des Wassers festsaugen und so den ganzen Tage hängen bleiben.
qv
Zur Biologie des Salmo salar.
Während einer Reise in Norrland im Sommer 1891 erfuhr ich. dass ein Lachsfischer, E. ANDERSSON, in der Nähe der Stadt Skellefteå geschlechtsreife Lachse im botnischen Meer- husen bekommen hatte. Da diese Sache sowohl von praktischem als wissenschaftlichem Interesse war, wurde es mir angelegen die Verhältnisse näher kennen zu lernen. Bei der Nach-. forschung ergab sich dann folgendes. Der erwähnte Fischer hatte sich seit mehreren Jahren mit Lachszucht beschäftigt; es war ihm aber oftmals schwer »Stammlachse» zu bekommen, weil er diese vom oberen Teil des Skellefteå-Flusses holen musste, selbst aber am Meeresufer wohnte. Es erwachte des- halb bei ihm der Gedanke sich selbst solche zu verschaffen. Es war ihm bekannt, dass die Lachse, die in die Flisse hinauf- steigen um ihren Laich abzulegen, schon im Mai und Juni die Wanderung antreten, obwohl das Laichen nicht fräher als im Oktober stattfindet. Er dachte also, wenn ich in den erster-
! Zwischen den Epithelzellen fanden sich doch Zellen, die ich als Leuco- cyten zu deuten geneigt bin, und diese spielen dann eine wichtige Rolle bei der Resorption.
BIHANG TILL K. SV: VET:-AKAD. HANDL. BAND 18. AFD. IV. N:O 2. 11
wähnten Monaten einige von diesen Lachse einfange und sie bis zur Laichzeit lebend halten kann, werde ich wvielleicht ge- schlechtsreife Exemplare bekommen. Obgleich dies jetzt nur scheinbar logisch richtig war, gelang es ihm die Sache zu einem gläcklichen Ausgang zu bringen. Er baute sich in der See einen Fischbehälter von Balken, deren Dimensionen die folgenden waren: Länge 40 Fuss, Breite 15 Fuss.
Bei niedrigster Wasserhöhe war er doch 6 Fuss tief hin- untergesenkt und ragte auch bei höchstem Wasserstand we- nigstens ein Paar Fuss öber die Wasser-Fläche um vorzubeugen, dass die eingesperrten Lachse iäbersprängen. Ausserdem war der Behälter eben fir denselben Zweck teilweise iberdacht. In diesem Behälter wurden jetzt die im Juni und Juli ein- gefangenen Lachse eingesetzt und lebend bis Ende Oktober und Anfang November gehalten. Da die Balken des Behälters nicht dieht an einander befesttigt sind, hält sich das ent- haltene ”"Wasser immer frisch und das Dach beschattet auch die Fische. Sie finden sich somit recht wobl.
Als die Laichzeit sich nähert, werden die Lachse getrennt und jeder fär sich in untertauchten Körben eingeschlossen um zu vermeiden, dass sie im Behälter laichen,! da der Laich fir die Zuchtanstalt abgesehen ist. Diese Körbe sind lang aber recht eng und der Körpergrösse der Tiere abgepasst, und sie missen natiärlich auch mit Deckeln versehen sein, damit die Lachse nicht hinausspringen.
In den Fischbehälter, der durch drei Steinkasten am Boden festgehalten ist und so stark gebaut ist, dass er Stärme und Wellen aushalten kann, werden am Ende Juni oder An- fang Juli eine gewisse Zahl in Netze gefangener Lachse ein- gesperrt, wie oben erwähnt ist. Natärlich werden die am wenigsten beschädigten ausgewählt und an ihnen heilt sich und versehwindet bald jede Spur der gelittenen Verletzungen. Die Lachse werden nicht gefättert und Fätterungsversuche wirden auch zweifellos ohne Erfolg sein, teils weil sie ein- gesperrt sind und teils weil sie niemals während der Wan- derung zum Laiechplatz, welehe Wanderung schon angefangen war als sie in den Netzen sitzen blieben, Nahrung aufzu- nehmen pflegen.
Wie ich oben erwähnte, bekam E. ANDERSSON schon beim ersten Versuche gönstige Resultate. Er hatte dann 6 Lachse
! Dies ist nämlich nach den Angaben E. ANDERSSON'S einmal geschehen.
12 EINAR LÖNNBERG, ICHTHYOLOGISCHE NOTIZEN.
(2 3, 49) eingesetzt, den letzten von diesen am 3 Juli, und am Ende Oktober hatte er Laich fär seine Zuchtanstalt. Bei meinem Besuch am 20 Juli 1891 hatte er in seinem Behälter 5 Lachse und durch Briefe habe ich später erfahren, dass er von 20 Oktober bis 3 November reifen Laich bekam.
Die Eier werden in Quellenwasser ausgebritet. Die Jungen werden meist in Flisse und Bäche ausgesetzt, aber es wurde auch gepräft, ob sie direkt in die See ohne Schaden versetzt werden könnten. Es wurde eine Grube am Meeresufer gegra- ben und mit Wasser von der See gefällt. Da die Jungen hier mehrere Tage leben konnten, wurden sie aus ihrem Gefängniss befreit und durften in die See auswandern.
Von dem obigen geht jetzt hervor, teils dass die Lachse in der See geschlechtsreif werden können, teils dass die Jungen sogleich in die See ohne abzusterben versetzt werden können. Von dem ersten dieser Befunde ergiebt sich, dass fär den Lachs weder der chemische Reiz des sässen ”"Wassers noch der fysische Reiz der Ströme und Wasserfälle nötig ist um bei ihm die Geschlechtsreife zum volligen Abschluss zu bringen. Es lag nämlich eine derartige Annahme nahe vor- handen, da der zum Laichplatz wandernde Lachs sich immer beiden aussetzte. Von NSchottland kennt man doch noch ein Beispiel von dem Reifwerden des Lachses in der See. Der Wert der oben erwähnten Resultate der Experimente E. AN- DERSSON'S wird aber nicht dadurch beeinträchtigt, weil sie för uns von einer besonderen Bedeutung sind. Durch sie wird es nämlich praktisch gezeigt, dass keime Hindernisse existieren, die es absolut unmöglich machen, dass die Tachse sich in der Östsee fortpflanzen können. Experimente, die man in Schottland angestellt hat, erzählen uns, dass es frei- lich mit dem dortigen Meereswasser sich nicht ausfähren lässt Lachseier auszubräten, aber es ist ein sehr grosser Unterschied zwischen diesem und demjenigen des botnischen Meerbusens, wenn man auf ihren respectiven Salzgehalt Röcksicht nimmt. Das Wasser im letzteren ist durch so vieles Sässwasser von den zahlreichen grossen Flässen, die da ausfallen, vermischt, dass man sich denken kann, dass es nicht unmöglich wäre in demselben Lachseier auszubräten. Dies scheint desto annehm- barer, als die kleinen neulich ausgebriteten Lachsjungen da ohne Beeinträchtigung ihrer Lebensfähigkeit ausdauern kön- nen. Die Möglichkeit ist also nicht ganz ausgeschlossen; eine
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:02. 13
Lachsrasse zu zichten, die sich in der Ostsee oder wenigstens im Bottenbusen fortpflanze. Es wäre wirklich von grosser Bedeutung, wenn etwas solches stattfinden könnte, und es ist um so mehr wichtig, diese schmackhafte und kostbare Fischart beizubehalten und wenn möglich kiänstlich zu vermehren, da gegenwärtig teils durch das SERVE erden der Flussmindungen känd teils arch die Holzflössen ihre alte Laichplätze mehr und mehr verloren gehen.
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BIHANG TILL K. SVENSKA VET.-AKAD. HANDLINGAR. Band 15. Afd IV. N:o 3.
UBER EINIGE
OBER-SILUNINCHE GIRRIPEDEN AUS GOTLAND -
CARL W. S. AURIVILLIUS.
MIT EINER TAFEL.
STOCKHOLM, 1892. OKTRYCKERIET. P. A. NORSTEDT
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Ja einem Bruchstäcke von Crinoideenfihrendem weichen Mer- gelschiefer aus der Schicht e der gotländischen Formation dicht bei Wisby wurde von Professor G. LINDSTRÖM im Mai 1891 ein Fragment eines Cirripeden entdeckt, welches zu der fol- genden Darstellung Anlass gegeben hat. Die Schicht ist nach seiner Angabe dieselbe, in welcher fräher die bekannten Reste von dem Scorpion Paleophonus THORELL & LINDSTRÖM und Pterygotus osiliensis F. ScHmioT gefunden wurden, und folglich mit der älteren Ludlowzeit gleichwerthig.
Der Fund ist mir von Prof. Linpström gätigst zur Be- schreibung iberlassen worden, dem ich auch die Ueberreichung der ibrigen unten erwähnten Cirripedenreste verdanke, welche -grösstentheils aus der Schicht c im Obersilur Gotlands her- stammen.
Alle diese sind deshalb so wichtig, weil fröher von der ganzen Gruppe der Cirripeden nur die Reste zweier und zwar nicht hinreichend begriändeter Gattungen, Turrilepas "Woopw. und Anatifopsis BARRANDE von der Silurzeit bekannt waren, während der bisher älteste sichere fossile Cirriped (Pollicipes rheticus MoorrE) aus der Rhätischen Formation stammt. Die unten erwähnten Funde zeigen aber an, dass sowohl die letzt- genannte Gattung, als auch die fräher nur bis in den Jura gefundene Scalpellum LrEAcH schon in der Silurzeit vertreten waren.
Alle der folgenden Darstellung zu Grunde liegende Exemplare sind in der Palzecontologischen Abtheilung des Reichsmuseums zu Stockholm aufbewahrt.
Stockholm im Januar 1892.
4 AURIVILLIUS, OBER-SILURISCHE CIRRIPEDEN AUS GOTLAND.
POLLICIPES LzEACH.
Deutung des in Fig. 1 abgebildeten Exemplars.
Es besteht das Exemplar aus sieben annähernd triangu- lären Schalen, von denen jedoch eine bis auf die Hälfte zer- brochen ist. Rings um deren Basis steht zunächst eine Reihe winziger Schäppcechen, sodann kleinere, wahrscheinlich in der Entwicklung begriffene Stacheln, endlich lange Stacheln, und zwar sind diese Bildungen nicht in emmer Längsreihe, sondern abwechselnd geordnet, so dass die Schuppen die Basis der langen Stacheln decken.
Was nun zuerst die Schalen betrifft, so gehören diese un- zweifelhaft zu dem Capitulum einer Pollicipes, welches vom Pedunkel scharf abgegrenzt gewesen; obgleich geringer an Zahl erinnern sie durch die in gleicher Höhe stehenden Basal- theile sehr stark an das Verhalten bei Pollicipes mitella L.
In Betreff der Schippehen- und Stachelreihen kann ich gerade wegen der Stellung der grossen Schalen und weil sie ausserdem durch ihre Bildung von jenen sehr abweichen, nicht umhin, sie als zu dem Pedunkel gehörig zu betrachten, jedoch ohne damit behaupten zu wollen, dass dieser im ganzen auf ähnliche Weise bewaffnet gewesen sei. Es macht äbrigens die Frage nach der Grenze zwischen Capitulum und Pedunkel auch bei jetzt lebenden Arten der Gattung Pollicipes (P. sertus Darw., P. spinosus Quvor & Garmarp) Schwierigkeiten, wo einerseits die grösseren Schalen nicht auf derselben Horizontal- ebene stehen und andrerseits die Schuppen oder Dörnchen theils ebenso wie jene gebildet sind, theils nach vorn allmäh- lich an Grösse abnehmend in die Pedunkelstachelchen iber- gehen.
Um sodann die Capitulumplatten zu besprechen, setzt schon die Form der links belegenen grösseren Schale ausser
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:083. DD
Zweifel, dass sie ein Scutum ist. Ebenso kann die mittlere mit Gewissheit als ZTergum gedeutet werden.
Was die rechte Schale betrifft, ist aus den basalen Schäpp- chen- und Stachelreihen ersichtlich, dass eine Drehung der- selben aus der urspränglichen Lage durch Druck bewirkt ist, wodurch ihr Mittelkiel dem Zuschauer schief zugewandt wor- den, anstatt dass in natärlicher Lage nur deren Profil sicht- bar gewesen ist. Durch ihre Lage auf dem Ricken des Capi- tulum, wo sie unmittelbar an den Terga liegt, muss sie folglich als Carina gedeutet werden. Jederseits von ihrer freien Spitze wird im Schiefer eine ähnliche Skulptur bemerkt, wie sie auf den genannten Schalen vorkommt. Wabhrscheinlich riährt sie von Bruchstiäcken des zerquetschten linksseitigen Scutum sowlie des Tergum her.
In Bezug auf die vier kleineren Platten, halte ich die beiderseits die Carima umstehenden fär Carwnolateraliu, um 80 eher, als der gebrochene Zustand der rechten darauf hindeutet, dass sie, urspränglich auf der anderen Seite befestigt, gewalt- sam nach dieser Neite hinäber gepresst worden ist, was ausserdem durch die Richtung der basalen Stacheln gewisser- massen bestätigt wird. Die zwischen Tergum und Scutum eingeschaltete Platte nenne ich, nach der bei den Gattungen Pollicipes und Scalpellum gewöhnlichen Bezeichnung, Laterale. Ueber die Deutung der links vom Scutum belegenen Platte, die doppelt so breit als die letztgenannte ist, kann man frei- lich anfangs in Ungewissheit gerathen. Bei näherer Unter- suchung geht jedoch hervor, dass innerhalb derselben keine Spur von eimmer anderen Platte zu sehen ist, die fragliche da- gegen mit der rechten Kante dem Scutum sich eng anschliesst. Dass ferner die Platte keine seitliche ist, dafär spricht sowohl die winkelige Basalkante als die jederseits der Mittelecke ver- schieden gerichteten Stacheln. Und zwar muss ich aus solchen Grinden die Platte als ein Rostrum deuten, welches also, weil eigentlich in der Bauchseite des Capitulum belegen, ähnlich wie das linke Carinolaterale und Carina selbst, bei der Ein- bettung durch Druck umgedreht worden ist, wobei äbrigens die äussere Hälfte abgebrochen sein mag.
Dass ausserdem noch Platten von anderer Bedeutung da- gewesen sind, ist kaum wahrscheinlich.
Bei Beriöcksichtigung der gegenseitigen Lage der also identificirten Schalen zeigt das fragliche Thier, unter den jetzt
6 AURIVILLIUS, OBER-SILURISCHE CIRRIPEDEN AUS GOTLAND.
lebenden Lepadiden, mit der Gattung Pollicipes die meiste Aehnlichkeit; besonders aber sprechen fir seine Aufnahme in diese Gattung Form und Lage der grösseren Platten.
Es kann die Art folgendermassen charakterisirt werden.
Pollicipes signatus n. sp. (Figg. 1—8.)
Capitulum aus 10 subtriangulären, in gleicher Höhe
befindlichen Platten, von denen 5 — Scuta, Terga und Carina — grösser und mit feinen Gribchen skulptirt, und 5 — Rostrum, Lateralia und Carinolateralia — um '/,
kleiner und mit Längsfurchen versehen sind. Der Pe- dunkel trägt dem Capitulum am nächsten glatte Schupp- chen, sodann rudimentäre Stacheln, endlich lange ge- furchte Stacheln; die Reihen mit einander abwechselnd;
ibrigens unbekannt.
Die Art weicht in zwei und zwar sebr wichtigen Gesichts- punkten von allen bisher bekannten ab:
1:0) Sind die grösseren Platten — Scuta, Terga und Ca- rina — durch ihre ausgeprägte Skulptur von den kleineren, nur gefurchten — Rostrum, Lateralia und Carinolateralia — ver- schieden.
2:0) Sind die grösseren Platten unter sich, sowie die klei- neren gleichgross.
Dieser äusseren Verschiedenheit liegt unzweifelhaft eine ontogenetische zu Grunde, nach den Zeugnissen der Entwick- lung lebender Lepadiden — Lepas, Scalpellum — sowie nach der Bildung der Ergänzungsmännchen gewisser Scalpellum- Arten zu schliessen.
Bei Lepas kommen immer nur 5 Platten zum Vorschein, nämlich Scuta, Terga und Carina, und es werden diese sämmt- lich schon im Cypris-Stadium angelegt durch die Entstehung der eigenthämlich gebauten sogenannten Primordialplatten, welche auch nach der Häutung der Puppe auf den Umbones der Platten eine Zeit lang zurickbleiben,
BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 18. AFD. IV. N:0 3. TY
Bei den hermaphroditen Scalpellum-Formen kommt eine grosse Menge Platten (12—15) vor, aber bei ihren Jungen sind nur Scuta, Terga und Carina durch Primordialplatten vorgebildet.
Wiederum bei den Ergänzungsmännchen von Scalpellum- Arten, z. B. von Scalpellum villosum G. B. SowerBY, die mit 6 Platten versehen sind, tragen ebenso nur Scuta, Terga und Carina, aber nicht Rostrum, Primordialplatten.
Es gewinren nun diese Thatsachen eine