Pasi: ai) a

Alex. Agassiz.

Ribrary of the Museum

OF

COMPARATIVE ZOOLOGY,

AT HARVARD COLLEGE, CAMBRIDGE, MASS.

Pounded by private subscription, In 1861.

Deposited by ALEX. AGASSIZ.

No. | bh 5)

pow b 1924 meee

‘“” / } ( ©

JUN 6 1927

Memoirs of the Museum of Comparative Sodlogy
AT HARVARD COLLEGE.

Wow, 265° INOS als

REPORTS

ON THE

RESULTS OF DREDGING,

UNDER THE SUPERVISION OF

ALEXANDER AGASSIZ,
IN THE GULF OF MEXICO (1877-78), IN THE CARIBBEAN SEA (1878-79), AND
ALONG THE ATLANTIC COAST OF THE UNITED STATES (1880),
BY THE

U. S. COAST SURVEY STEAMER “ BLAKE,”

Lievt.-Com. C. D. Sicsper, U.S.N., anp Commanper J. R. Barriett, U.S. N., Commanprinea.

XXIV.” Pree.
Report on the Echin. By ALEXANDER AGASSIZ.

(Published by permission of Cartite P. Parrerson and J. E. Hriearp, Superintendents
U.S. Coast and Geodetic Survey.)

WITH THIRTY-TWO PLATES.

CAMBRIDGE:

Wrinted for the fMluseum.
SepreMBer, 1883.

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INTRODUCTION.

Tur Preliminary Reports on the Echini of the Blake Expeditions for
1877-78, for 1878-79, and for the summer of 1880, were published in Vol.
V., No. 9, Bull. M. C. Z., and Vol. VIII., No. 2, Bull. M. C. Z. In the former
Report will be found all the Stations occupied in the Gulf of Mexico and
Straits of Florida; in the latter, the Stations explored along the West India
Islands and the Atlantic coast of the United States. I give in this Report,
therefore, only principal localities in sufficient number to indicate the geo-
graphical range and bathymetrical distribution of each species as determined
by the dredgings of the “Blake.” In the Report on the Echini of the
Challenger Expedition I have given a list of the bathymetrical and geo-
graphical distribution of all the species of Echini then known, including the
species collected by the Blake Expeditions. The Preliminary Reports on the
Deep-sea Kchini, collected by Mr. Pourtales off the Florida Reefs, were
published in the Bull. M. C. Z., Vol. I., No. 9. The final Report was incor-
porated in Part I. of the Revision of the Echini under the name of “ East
Coast Echini,” Ill. Cat. M. C. Z., No. VII. Mem. M. C. Z., Vol. III., 1872-74.

The importance of the collection of the Echini brought together during
the cruises of the “ Blake” is well shown by a comparative statement of our
knowledge of the Caribbean Echinid Fauna before and after the explorations
undertaken under the auspices of the United States Coast Survey.

There are now known eighty-three species of Sea-urchins from the Carib-
bean Fauna. Of these, eleven were added by the dredgings of Count
Pourtalés in the “ Bibb” and “ Hassler,” nineteen were discovered by the
“ Blake,” and thirteen species previously known from other districts were

dredged for the first time in the Caribbean and adjoining seas by the Coast

iv INTRODUCTION.

Survey Expeditions, so that the list of species has been more than doubled
by the dredgings made since 1876.

In consequence of the great delay in preparing the illustrations of the
more minute structure of the Salenidew, the Echinothuriz, and many of the
less well known Spatangoids, the concluding Part of this Report will appear
on their completion.

The details of the geographical distribution of the Echini of the “ Blake ”’
having already been given in the Prelimimary Reports (Bull. M. C. Z., Vol. V.
No. 9, 1878, Vol. VII. No. 2, 1880), to avoid repetitions I merely refer to
the previously published records, as well as to the list of the dredging sta-
tions occupied by the “ Blake” (Bull. M. C. Z., Vol. VI. No. 1, 1879, Vol.
VIII. No. 4, 1881). These give the position, the depth, the temperature, and
the character of the bottom. On the completion of the Reports by the differ-
ent specialists, who have kindly consented to work up the collections of the
“ Blake,” including the examination of the bottom samples, I hope to make
a revision of the geographical and bathymetrical distribution of the various
groups, so as to give a good picture of the animals associated at the prin-
cipal localities which make up the Fauna characteristic of certain well-defined
regions. Nothing can be more different, for instance, than the animals
found associated on the rocky bottom along the southern slope (in deep
water) of the Florida Reef, on the Pourtalés Plateau, with its predominance
of Corals, Rhizocrini, and Starfishes, from those found in the calcareous
ooze of the trough of the Gulf Stream (Lamellibranchiates, Holothurians,
&e.); and again from the association of the masses of Gorgonis, Saleniz,
and Terebratulx, off the north coast of Cuba, brought up in a single haul of
the trawl. Nor can there be a greater contrast between the inhabitants
of the Pteropod ooze in deep water off the west end of Santa Cruz, with
its preponderance of Phormosomex, of Asthenosome, and Hyaloneme, and
those of the forests of Pentacrini and Gorgonixw, and the accompanying
Comatule and Ophiurans, living in such abundance on the windward coast
of St. Vincent.

We may contrast, again, the deep-water Fauna off the Tortugas, in the

coral ooze, mainly made up of a most remarkable association of Fishes

INTRODUCTION. Vv

and Crustacea, with the hauls in deep water, at special localities, made up
entirely of thousands of specimens of single species, either of Ophiurans,
of Echini, of Comatulx, of Crustaceans, or of Gorgonie.

Take again the bottom along the ridges between the West India Islands,
or along the course of the Gulf Stream off the Carolinas, which are swept
nearly clear of all animal life, and compare that to the rich and varied Fauna
found at the same depths along the continental shelf farther north, and
along the western shelf of the Windward Islands, on the lee side, in the
Caribbean; or compare these Faune in turn with the mass of animal life,
mainly composed of Gorgonix, of Caleareous and Horny Sponges, found
upon the great plateau on the west of Florida and on the Yucatan Bank ;
there can be no greater contrasts within the narrowly circumscribed areas
I have mentioned, all belonging to the West Indian Fauna taken as a
whole. This clearly indicates great faunal contrasts in very limited areas,
differing principally in the character of the bottom, and where the physical
conditions, such as temperature, depending mainly upon currents and winds,

are in striking opposition within comparatively moderate distances.
ALEXANDER AGASSIZ.

Campripcn, Mass., September 1, 1883.

©. ON Gene Es.

SPECIES ARRANGED SYSTEMATICALLY.

Norr. — Species marked * were discovered by the ‘‘ Blake” ; those marked p were first dredged by Mr.
Pourtal’s ; species marked °* and °p were previously known from other localities, and subsequently dredged
in the Caribbean and along Florida by the ‘‘ Blake” or Mr. Pourtalés. The species without any notation were
previously known from the Caribbean region.

Pace

CipARIS TRIBULOIDES Bl.. . . . > 3 6 tt Ce oe ome ee meee Cones 9

FTN OROCIDARIS ME AR TEETIN Ae AG.) f-UelTe Hh gael O-=2//etsmectnCmn <n LV leu ntin Tunes 9
WDieovormovuene) 1Biskicae ING ING PARI IAE OG Jk ds) 5 5 ye 6 ll lll ll DD
“DID oon) NaNO NON DAG Ne Gm bo oll ll ll
FPLOROCIDARIS | SHARRERI elt pA fl, LL El ey ae Hig Selene me eels) seus) eames) uesnn Le?
*Sarenta Patrersont A. Ag. Pl. IV. Figs. 3-23; Pl. V.; Pl. VI. Figs. 18-23 . . 18
PISATENTAUGVAIRISPINAY Ate Aon 8PIs Vl Bigs. 117 en i a) ches mn LO
ATINGWA TUNER TCT G 6 bp bo oo oll lll
PALODOCID ARIST SCULETAW AT As 9. fa: RNC Na Soticl es oc Ge 22
PRLODOCIDARISESCULAT AWE AarA Gran 0) |.) 9 ol Cn IMEEM on ed er eet ee oO
PCGroprEnRus KLORMANUS AG Ao. Pl VAUE PIS VA ec) sy sO
DIADEMANSETOSUMalGIalyarc cin 21 acta GO EM UNTER Toemel fe, Gil <1 ao penis Se 24
INT AMO MDVAUN Now. G 6 0 6 OD 0 > 0 0% o 9 © BO OO ONO 55 Om re:
“o INGEODDVOOWUN PupunneAumene IAIN JAIL IDG 5 6 6 5 bo og 6 6 0 0 6 8 6 74)
<SNcemoon oon dNeora JN IN JAG IOME ) 3 5 6 5 o 0 6 60 6 6 8 8 OO
CASTHENOSOMA aystRIx AC Alo) (PE XU PL OXUV ae ee ss ee
°* PHORMOSOMA PLACENTA Wyv. Thoms. Pl. XJ, Pl. XV. Figs.38-19 . . . . - 30
OPHORMOSOMANURANTS) Wyv. Lhoms: PeXe PRX eee) se 2 OO
iGHINOMETRASSUBANGULARIS’ Desml: =) 4) ces eee Sle). 2 4 OO
SrRonGyLOcENTROTUS Droépacniensis A. Ag. . . . . - - s+ + + + + + + 36
AMOR 5 Gi wo wo so cee oo ooo 6 (oo
PiTumnnonnusrwmcuraus A; Ag. . 4 «2 » w 2 ee 2 ee we s 2 88
p TRigonocmamimMEIAAD AG << 66s 4 oh ss kt ee we FOB
PL CHINUST GRACIEISBAGEAC TEES jn thts on CM ch See mr eo os
CRIN CHINUS NORVEGICUSM DU OnXOLs seu) fee ee i oe
< HOnINUs? WArEISED ON CREAMS hao a Geis Sin ete oe ce 89
Toxopneustes vaRrecatus A. Ag. . 2 2 ee ee ee ee ee 8D
Hipponoé ESCULENTA A. Ag. «ooh (VEER Roar WS ie aaa NC mee

Vill CONTENTS.

mil Neasoroleh ae Wines) irises Veil Jia Ge pMOn OR 0 o G © 5 @ o & «
°* CLYPEASTER LAvTIssimus A. Ag. Pl. XV. Figs. 3,4; Pl. XV¢. Figs. 3, 4 .
°pCLYPEASTER Ravenetitit A. Ag. Pl. XV. Figs. 1,2; Pl. XV¢. Figs. 1, 2
CLYPEASTER sUBDEPRESsSUS Agass. Pl. XV“.
EcHINANTHUS ROSACEUS Gray
EcuiNaracunius PARMA Gray
NCOPERMUCHEDINT -AGaSs: QFc i. ¢ 1 bs eo Ree 8s
Ecuryoniéus semitunaris Lamk. :
pep NEOLAMPAS rosTELLATA A. Ag. Pl. XXII. ES, ear
°p EcHINOLAMPAS DEPREsSA Gray. Pl. XVI, Pl. XXIV. Figs. 1-5 .
Conotampas A. Ag. Sep ORaeENe ce
* ConoLampas Stasper A. Ag. Pl. XVII.
P POURTALESIA MIRANDA A. Ag. «1 Sa ae
°* UrRrcuinus narestancs A. Ag. Pl. XX VI. Figs. 1-3
°*PaLmorropus JOSEPHINE Loyén. Pl. XXIIL. Figs. 5-14
*PaLtmorropus Tnomsont A. Ag. - ia ae Pi eae ol
* PaL@osrissus Hirearpi1 A. Ag. Pl. XXIV. Figs.6-15 . ... .
P HomoLampas rracitis A. Ag. . it so
P PALEOPNEUSTES Cristatus A. Ag. Pl. XXI. oe eke: Wrote ee
* PALEOPNEUSTES HysTRIX A. Ag. Pl. XVII, Pl. XIX. Fig. 2 (lower fig.)
* LINOPNEUSTES LoNGISPINUS A. Ag. Pl. XIX. Fig. 1 (upper fig.) ; Pl XX. . .
* Macropneusres spaTaNcorpes A. Ag. Pl XXVIZ. ..... .
*THemiaster Menrzi A. Ag. .

* RHINOBRISSUS MICRASTEROIDES A. Ag. Pl. XXIIL. Figs. 1-4, Pl. XXVI. Fig. 4 .

°* BRISSOPSIS LyRIFERA Agass. Pl. XXVI. Figs. 7-18 .

Pp AGassiziA EXCENTRICA A. Ag. Pl. XXV.
Mroma ventricosa Liitk. . . . ee LEMS

°* SCHIZASTER FRAGILIS Agass. Pl. XXVIII. Figs. 8-14 . 1. . . ss .
* ScHIZASTER oRBIGNYANUS A. Ag. Pl. XXVIII. Figs. 1-7.
* ScuIZASTER (PERIASTER) Limicota A. Ag. Pl. XX VI. Migs.5,6. . . . .

OricIn or THE West Inpian (Carrpsean) Ecurip Fauna . . . . .

TABLE SHOWING THE GEOGRAPHICAL AND PALONTOLOGICAL RELATIONSHIP OF
WESTAINDIANJEIGHINE 5 = . . « < -« )s 0 Seen

THE

85

Ra EO ris

ON THE

RESULTS OF DREDGING,

UNDER THE SUPERVISION OF ALEXANDER AGASSIZ,

IN THE GULF OF MEXICO (1877-78), IN THE CARIBBEAN SEA (1878-79), AND ALONG
THE ATLANTIC COAST OF THE UNITED STATES (1880),

BY THE U. 8. COAST SURVEY STEAMER “ BLAKE,”

Lrevr.-Com. C. D. Siasser, U. 8, N., anyp Commanper J. R. Barriert, U. S. N., Commanpine.

XXIV) PAR

Report on the Echin, By ALEXANDER AGassiIZz.

Published by permission of Cartive P. Patrerson and J. E. Hiern, Superintendents
Y Pp ) SUE

U. 8. Coast and Geodetic Survey.)

Cidaris tribuloides Bu.

Off St. Kitts, 250 fathoms. Flanegan Passage. Dik ne
4/4990
Lat, 24° 44’ N., Long. 83° 26’ W. 37 fathoms. ies

*Dorocidaris Bartletti A. Ac.
Dorocidaris Bartletti A. Ac. Bull. M, C. Z., VIIL., No. 2, p. 69, 1880. we,
Montserrat to Barbados. 88-398 fathoms. vk age

Pl. IL. Figs, 16-27.

At St. Vincent and at Martinique were first collected a number of re-
markable spiny transversely banded radioles (Pl. II. Figs. 18, 19, 26, 27)
similar to those of Goniocidaris bispinosa, and which I had already noticed in
the earlier Preliminary Reports of the Blake Expedition for 1877-78. From
Barbados a few specimens of Cidaris were dredged, showing these radioles
to belong to a species of Dorocidaris differing from D. papillata and D.

"s * Species marked * were discovered by the “ Blake.”

10 DOROCIDARIS BLAKEI.

Blukei in the shape of the plates of the abactinal system (PI. I. Fig. 17).
The ocular plates are in contact with the extremities of the large anal plates
inserted between the genital plates; the other plates of the anal system are
of a more uniform size than in the other species of the genus. In a speci-
men measuring 50 mm. in diameter, there are 7-8 primary interambulacral
plates ; these are covered by a comparatively coarse, irregularly arranged
secondary granulation. The poriferous zone is somewhat flexuous, the fur-
rows more distant, and the median ambulacral granulation finer, than in
the other West India species of the genus. The ambulacral papille and
those at the base of the primary radioles of D. Bartletli are nearly of uni-
form size; in D. papillata, those surrounding the radioles are somewhat
larger, and in D. Blakei they are still more different, being comparatively

much wider and flatter than the narrow ambulacral papille.

*Dorocidaris Blakei A. Ac.

Dorocidaris Blakei A. Ac. Bull. M.C. Z., V., No. 9, p. 185, Pl. TV., 1878.
Dorocidaris Blakei A. Ac. Bull. M.C.Z, VIII., No. 2, p. 70, 1880.
Off Havana, 175-450 fathoms.
|

Santa Cruz to Barbados, 163-270 fathoms. [@ 3
Pl, Pl. IL. Figs. 1-16.

This species (PI. I.) is perhaps the most interesting of the recent Cidaridex.
Thus far the living Cidaride known have not shown any great or striking
variety in the form of the radioles. With the exception of some of the
recent species of the genus Gonocidaris, the radioles as a whole are charac-
terized by their great uniformity, while among the fossils of the family the
great variation in the shape and size of the radioles of some of the Jurassic
and Cretaceous species is most remarkable. In the description of species of
the recent Cidaridie, it has not been unusual to lay great stress upon the
differences noticed in the shape and ornamentation of the radioles, Com-
parative studies of recent and fossil types have shown the practice to be
dangerous, and the discovery of D. Blake’ plainly proves that hereafter we
must proceed most cautiously in the determination of species from the char-
acters of the radioles alone, no matter how strikingly they may appear to
differ. Certainly, if the present species had been dredged without its two or
three huge fan-shaped spines, it would have been unhesitatingly placed in the
genus Dorocidaris, and been perhaps referred even to D. papillata, although
there are differences in the coronal plates of the test and in the abactinal

DOROCIDARIS BLAKEI. 11

system (PIL. II. Figs. 1, 2) which would undoubtedly lead to their being con-
sidered specifically distinct. Yet, if the isolated huge fan-shaped radioles
had alone been dredged, radioles (Pl. H. Figs. 7-10) nearly identical in shape
with those of the Jurassic Rhabdocidaris remus Des. (Phyllacanthus Br.) few
paleontologists would have hesitated to refer them to that genus.

A comparison of the differences in the test of this species and of D. papil-
lata shows that the coronal plates (PI. II. Fig. 1) have a comparatively larger
and more elliptical scrobicular area, surrounded by a single row of larger
secondary tubercles; the tubercle and boss are much smaller, and the tuber-
culated spaces of the median interambulacral area are also narrower. In a
specimen measuring 37 mm. there are 6-17 primary interambulacral plates,
while in a smaller specimen of D. papillata, measuring 55 mm., there are 7-8
primary interambulacral plates. In the ambulacral areas the poriferous zone
is nearly as broad as the median ambulacral spaces (PI. II. Fig. 1), while in
D. papillata it is narrower; the secondary ambulacral tubercles are also
smaller than in that species. It also differs from D. papillatu in having a
smaller anal system, but this is covered by a larger number of plates inside
the outer row (Pl. IL. Fig. 2) than in D. papllata. The ornamentation of the
radioles is the same on the long fusiform, or cylindrical, or the more or less
fan-shaped radioles of the test (PI. H. Figs. 8-10); these figures show well the
gradual passage from a long, sharp-pointed, cylindrical radiole (Pl. II. Fig. 3)
to a huge fan-shaped radiole (Fig. 10), through the successive stages of Figs.
4-9, in which the radioles become little by little more flattened and spread-
ing at the extremity. As the radioles become more fan-shaped, the rows of
spinules are gradually changed into minute serrations, spreading more and
more, and becoming somewhat less prominent towards the extremity, rows of
smaller serrations being intercalated as the extremity of the radioles becomes
more and more fan-shaped. The broad end of the fan-shaped radioles is
sometimes slightly concave.

In the first specimens of this species, dredged by Captain Sigsbee, there
were no radioles showing the intermediate stages here figured between
the long, sharp, cylindrical radioles of Plate Hl. Figs. 3, 4, and such tfan-
shaped ones as are figured in Plate II. Figs. 9, 10. Enough has been
shown from the examination of this species to show how little we are as
yet able to determine among the Cidaride the value of either generic or
specific characters. Before we can hope to make the much needed accu-
rate revision of this family we need a large mass of material, especially

12, POROCIDARIS SHARRERI.

from the fossil species, in the way of spines associated with their respect-
ive tests.

When alive these Echini were of a brilliant vermilion color.

Among the specimens of D. Blake there are a number without fan-
shaped radioles ; others, in which there were only one or two of the slightly
flattened radioles similar to those of Plate I. Fig. 5; others again, in which
there were a few radioles like those of Plate Il. Fig. 7; and others, in which
a few of the fan-shaped radioles took the extraordinary development we find

figured in Plate I.

Dorocidaris papillata A. Ac.

For localities see Bull. M. C. Z., V., No. 9, p. 185, 1878; Bull. M.C. Z., VIIL, No. 2, p. 70, 1880.

On our coast this species has been found by the “ Blake” as far north as
Lat. 32° 33’ N., Long. 77° 30’ W. Along the Florida reefs, in the Gulf of
Mexico, and along the West India Islands, it is the most common sea-urchin
found from about 100 to 500 fathoms. I have dredged it to a depth of 842

fathoms off the Grenadines.

* Porocidaris Sharreri A. Ac.

Porocidaris Sharreri A. Ac. Bull. M. C. Z., VIII., No. 2, p. 71, 1880.

Nevis, Barbados, 122-356 fathoms.

Pl. IID, Pl. IV. Figs. 1, 2.

This species differs from its Atlantic congener, P. purpurata Wy. Th., in
having a comparatively larger number of ambulacral plates, —no less than
fifteen for the median interambulacral plates (Pl. IV. Fig. 1) in the largest
specimen collected, while in a specimen of P. purpurala of nearly the same
size there are only ten; the ambulacral granulation is also much finer, and
the large areolar ring of comparatively large granules is flanked by smaller
granules arranged in irregular lines parallel to the suture. We find no
such arrangement in the coarse granulation of the interambulacral plates
of P. purpurata.

This is a larger species (PI. III.) than either of the other recent ones thus
far known. The two largest specimens collected were males; a single small
female, measuring slightly over an inch in diameter, shows that in this
species, as in P. elegans, the genital openings are placed within the genital
plates (Pl. IV. Fie. 2 ).

SALENIA PATTERSONI. its

The abactinal system (Pl. IV. Fig. 2), which is but sparsely covered by
papilla, is remarkable for the size of the anal system, comparatively larger
than in the other species of the genus, and for the elongate genital and
ocular plates.

The primary radioles are smooth, and uniformly tapering; in one of the
specimens, which was of a light greenish pink color when alive, the spines
are white with a delicate brownish-pink base. In the other large specimen
they vary greatly in shape, from the peculiar serrated, short, flattened spines,
surrounding the actinostome, characteristic of this genus, to long, slender,
cylindrical spines, straight, or sometimes slightly curved, equalling in length
twice the diameter of the test, and finely fluted for the whole length, or
to the shorter radioles, gradually becoming thicker towards the tip, with
coarser fluting ; we also find some spines with slightly cupuliform tips, as in

Goniocidaris. The largest specimen measures fully 72 mm. in diameter.

*Salenia Pattersoni A. Ac.

Salenia Pattersoni A. Ac. Bull. M. C. Z., V., No. 9, Fig. 1, p. 187, Pl. V., 1878.
Salenia Pattersoni A. Ac. Bull. M.C.Z., VIII, No. 2, p. 72, 1880.

Off Havana, Caribbean, West Indies.
Pl. IV. Figs. 3-23; Pl. V.; Pl. VL. Figs. 18-23.

This is the most exquisitely colored of the living Salenidee thus far known.
When alive the test is of a light cream-color. The shafts of the primary
spines are banded alternately with cream-color and brilliant vermilion, the
colors being nearly equally divided. This coloring at first glance gives to
this species very much the appearance of the Florida species of Coelopleurus,
The secondary spines are also cream-colored, separated at the base by dark
violet belts, extending from the apical to the actinal system along both the
median ambulacral and interambulacral lines. Similar dark violet lines
separate the genital plates and the superanal plate from one another, the
dark lines of the thedian ambulacra and interambulacra extending some dis-
tance into their corresponding genital and ocular plates. The primary spines
are from three to four times in length the diameter of the test, and carry mi-
nute, sharp, irregular serrations; these are frequently worn off, the radiole
then presenting a nearly smooth surface, slightly granular. These spines
are remarkably uniform in their appearance, differing merely in length,
and we do not find among them the great variation so characteristic of the
primary spines of S. varispina, the only exceptions being the Porocidaris-

14 SALENIA PATTERSONI.

like spines found near the actinostome. The papilla or secondary spines are
long, with a rounded slightly concave extremity. The outer edge of the abac-
tinal system and the median line of the ambulacral area are thickly studded
with minute globular pedicellariw. The plates of the abactinal system are
covered by a coarse granulation; this towards the outer edge of the geni-
tal plates becomes minute sessile spines. The sutures between the genital
plates, as well as the lines separating them from the abactinal part of the
ocular plates, are deep. The anal system carries short, stout, pointed spines.
None of the genital pores, with the exception of the madreporic genital, are
very distinct; the madreporite consists of a few minute pores adjoining the
large genital pore. The ocular plate opposite the superanal plate nearly
touches the anal system, approaching it much closer than is the case in
S. varispi.

In specimens measuring 12 mm. in diameter, there are usually from five to
seven primary tubercles in the interambulacral area. The secondary tuber-
cles, carrying the flat papillee, are arranged vertically in open ares round
them; and these ares, running together along the median interambulacral

PiVCS

line, form two wavy vertical rows of tubercles, closely packed, which g

to the median interambulacral area a somewhat sunken aspect, as in Go-

Y

niocidaris. The ambulacral tubercles, as in S. varispina, resemble in their
arrangement those of Hemicidaris, forming two vertical rows; they are
largest near the ambitus, diminish rapidly in size towards the actinostome,
and more gradually towards the apical system. The largest ambulacral
tubercles are not larger than the secondaries surrounding the primaries of
the interambulacral area, The ambulacral zone is narrow; the pores are
arranged in a slightly undulating line, following irregularly the outline of the
primary plates in the interambulacral area. Smaller and larger specimens
differ only in the size of the primary tubercles, those towards the actinos-
tome increasing but slowly in size as the diameter of the test enlarges. The
principal differences to be noticed are in the greater number of imbricating
plates which cover the actinal membrane in the older specimens, as compared
with the more simple arrangement of the plates and their smaller number in
earlier stages. In younger specimens the five pairs of large buccal tentacles
cover nearly the whole actinostome; they next become separated from the
actinal edge of the test by a few irregularly arranged imbricating plates, and
as the rows of plates increase they form also narrow zones between the pairs
of buceal plates in extension of the interambulacral areas, until in the older

SALENIA VARISPINA. 115)

stages collected the pairs of buccal plates are quite distant. In the abactinal
system the differences due to age are quite marked. The plates covering
the anal opening are few in number, and comparatively large in the younger
stages; with increasing size the plates become more numerous and relatively
smaller, and carry from one to two minute tubercles. The granulation of
the genital and ocular plates becomes also more distinct with increasing size,
forming more or less regularly radiating lines; the outer edges of the plates
of the genital ring become also somewhat indented, the inner edges of the
ocular plates are grooved in the extension of the radiating lines of the gran-
ules of these plates. The gills of S. Padersow are stouter and less branching
than the gills of 8. varispina, and the few spheridia noticed are remarkable
for their small size and globular outline; one or two spheeridia are placed in

the ambulacral areas close to the edge of the ocular plates,

Salenia varispina A. Ac,

This species, of which only a single young specimen had been collected by Mr, Pourtalés, has been
found from Lat. 24° 36’ N., Long. 84° 5’ W., as far as Granada and Barbados, in depths of
334-1,200 fathoms. It is most abundant in depths between 400 and 600 fathoms.

For other localities, see Bull. M. C. Z., V., No. 9, p. 186, 1878; VIII,, No, 2, p, 71, 1880.

Pl. VI. Figs. 1-17.

How far the obliquity of the axis of the apical system is a structural feature
of sufficient importance to be considered a generic difference, it is difficult to
decide. In Salenia we undoubtedly have in the asymmetrical arrangement
of the plates of the apical system a feature somewhat prominently developed,
which is found in all Echinoderms, and which is due to the original mode of
growth of the plates of the embryo Kehinoderm in a spiral curve. Traces of
this are plainly to be seen in the unequal development of the genital and
ocular plates throughout the group of Kehini, in no one of which do we find
the five plates either of the genital or ocular system symmetrically devel-
oped, or exactly symmetrically arranged in relation to a longitudinal axis.
We find this in the apical system of the Palechinide, the Echinothurix, the
Cidaridxe, the Echinidx, the Clypeastroids, and the Spatangoids, as well as
in the asymmetrical test of all young Echinoidea; and perhaps we may trace
the different degree of development of the five series of ambulacral and inter-
ambulacral zones throughout the group of Echini to such a primitive differen-
tiation. As Neumayr has suggested, the appearance of the suranal plate in
Salenia may not have the meaning or importance which has been attached to

16 SALENIA VARISPINA.

it from a morphological point of view when compared to the single large anal
plate of young Echini. Yet, while it may perhaps not be an embryonic fea-
ture of the Echini which runs back through the Echinoid series of the earlier
paleozoic times, it may yet be one of those cases of the sudden reappearance
of an ancient structual feature after a long period of time, as is also perhaps
the five-valved actinal opening of Palzeostoma. Iam inclined to look upon
the suranal plate of Salenia as strictly homologous with the central plate of
the dorsal surface of Starfishes, which, while it recalls the Crinoidal affinities
of the Echini, yet has not played the important part in the development of
the Echinoid series which it did in the Starfishes or Crinoids.

As far as the plates of the anal system are concerned, the embryonic type
of many plates arranged in more or less irregular concentric rows round the
anal opening, such as we find it in the oldest palseozoic Echini, has remained
remarkably persistent throughout the group to the present day. Even in
the Spatangoids and Clypeastroids, in which the anal system has become
disconnected from the apical system, the same general embryonic type has
been retained in nearly all the principal groups, with the exception of a few
types, such as Kchinocidaris, and some of the Clypeastroids and Spatangoids,
in which the number of anal plates has become reduced, and they form
a pyramid over the anal system; a structural feature, however, which we
should remember is already found in some of the earliest known Crinoids.
From what | have shown of the mode of breaking up of the anal system* in
some very large specimens of Arbacia, the pyramidal anal covering may have
been the earliest type of plates of the anal system in Crinoids, and the split-
ting up of the plates of the anal system, at first few in number, may be a
feature characteristic of the more recent Echini. Such a splitting up actu-
ally takes place in the growth of the plates of the anal system of Salenia.
In very young stages of S. Padtersoni we have a suranal plate and five anal
plates covering the anal system; while in old specimens the anal system is
covered by a number of smaller plates, due to the splitting up in part of the
original plates at their apex, and in part to the formation of new plates
round the anal opening with the increase in size of the anal system.

How far we are justified in considering the anal plates of the recent Des-
mosticha as homologous with the dorso-central plate of young Starfishes and
of Comatula, seems somewhat doubtful. P. H. Carpenter + has well discussed
some of the difficulties to be met in adopting the view Lovén and myself have

* Challenger Echini, p. 56. + Quart. Journ. Mie, Soc., XVIII. 357.

SALENIA VARISPINA. 17

taken of the homologies of the apical system of Echini and of the plates of
the embryonic Comatula in its Pentacrinus stage. Neumayr’s suggestion
of the morphological value of the anal plates of the Palaechinidx and Cida-
ridx has thrown considerable light on this question, and shows us the possi-
bility of a number of anal plates m Echini, say five for instance in Echino-
cidaris, being the homologue of the dorso-central plate of the Pentacrinus
stage of Comatula. Of course we should remember that, in making this
homology, we are comparing plates, which while they occupy the same
structural position, have a very different physiological value. As I have
already stated, we have the most positive proof of the origin of the dorso-
central plate of Starfishes and Ophiurans as a single Y-shaped rod appearing
simultaneously with the five basals; but we have no such definite data either
for the Echini or for the Comatule while within the Pluteus. Such informa-
tion would go far towards settling this disputed homology, for at present we
are obliged to draw our conclusions from a comparison of the more advanced
stages of development. The discovery of a pedunculated Starfish by the
“Travailleur,’ the Caulaster of Perrier,* may throw important light on the
homology of the centro-dorsal plate of the Starfishes and of the Crinoids.

The discovery by Laube in the Trias of the genus Tiarechinus of Neumayr
shows that the pyramidal anal covering, composed of a few large plates,
which appears in some of the earliest Crinoids known, has persisted or re-
appeared after a long lapse of time, during which the greater part of the
Palechini were provided with an anal system protected by one or two con-
centric rings of numerous plates; this Jast structural feature characterizing
nearly all the modern Echini, only a few Clypeastroids and Spatangoids, and
among the Desmosticha the Echinocidaride, still retaining the antique struc-
ture of the anal system, while in nearly all Echini from the oldest to those of
the present day we may imagine the numerous anal plates to have been the
result of the splitting up of the five (or more?) plates of the anal pyramids
into numerous smaller plates. Where this splitting up took place regularly,
we have the anal system of the Palwechinide, Cidaridee, etc.; where, on
the contrary, one plate resisted, we have what exists in Salenia and all the
recent Echini, in which one of the anal plates has a great prominence over
the others. The Salenia-like structure, therefore, may appear at any time,
and disappear again, without perhaps having so important a morphological
value as I was at first inclined to give it when I called attention to the

* Comptes Rendus, December 26, 1882.

18 SALENIA VARISPINA.

existence of a large permanent anal plate in the young of many Echini
among the Desmosticha.

I was in hopes that the examination of the series of young Saleniz dredged
by the “ Blake” might throw some light on the formation of the suranal
plate, and its homology with the single large anal plate of the early stages
of young Echini belonging to other families. On examining these young
Salenie I find that the abactinal system occupies a comparatively much
greater space of the abactinal surface of the test than in the larger speci-
mens. But in all the young stages, even when not measuring more than
1.5 mm. in diameter, the arrangement of the plates of the abactinal system
does not differ from that of the older specimens, the suranal plate being
only proportionally somewhat smaller. In the youngest Salenia collected
(1.5 mm. in diameter) the sutures between the genital and ocular plates are,
as in all young Kchini, somewhat indistinct, and it is difficult to define the
exact limits of the abactinal system. As I have already shown in other
young Kchini (Strongylocentrotus, Echimus, Arbacia, Diadema, etc.), the
coronal plates of the test and the plates of the abactinal system are very
indistinct in the stages immediately following the resorption of the Pluteus,
while the actinal system is well defined. It is only later that the separation
of the ambulacral and interambulacral areas can be traced ; at about the same
time the limits of the abactinal system become defined; and still later, the
separation of that system into its component plates surrounding the anal
system, which from the earliest stages is readily recognized. In the young-
est stage of Salenia the anal system is distinctly pentagonal, and covered
by eight large triangular plates with rounded tips; the plates carry small
granules supporting minute sessile papille similar to those found on the
genital and ocular plates, but smaller.

As in other young Echini, the anal system is comparatively large; the
suranal plate is at first quite small, a narrow plate on the side of the anal
system opposite to the nearest ocular plate. It appears to gain in size at the
edges adjoining the genital plates. As fast as the plates of the genital ring
increase, the pentagon they form round the suranal plate enlarges, and the
outer edges of this plate keep pace in their growth with that of the imer
edges of the adjoining genital plates. The genital and ocular plates carry
three or four large granules irregularly placed on the plates, with a row of
granules forming a line round the edge of the anal system. There are as
yet no traces of the genital or ocular openings. The whole of the abactinal

SALENTIA VARISPINA. 19

ring is striated, the lines forming irregularly lozenge-shaped figures, arranged
as they have been figured by Lovén for Salenia goésiana (Lovén, Etudes sur
les Echinoidées, Pl. XIX.). The limits of these figures, both in the smallest
specimen and in one measuring 2 mm. in diameter, are somewhat indistinct,
owing to the coarse, spongy granulation of the limestone tissue of the plates
of the abactinal system. In the majority of the young specimens examined,
this striation could not be detected at all, and in older specimens, measuring
from 4-8 mm. in diameter, I was unable to do more than trace portions of
this striation on account of the granulation of the plates.

TI am now inclined to consider Salenia goésiana of Lovén as identical
with S. varispina ; it certainly agrees very closely with the young of S.
varispina of the same size (3.5 mm.) collected by the “ Blake” in the West
Indies. These young specimens show, as I have stated above, the peculiar
striation of the abactinal system of S. goésiana, though the size of the tuber-
cles of the ambulacral system is somewhat smaller in the young of our
S. varispina than in the figure given by Lovén. The abnormal position of
the madreporie body in the original type specimen of S. varispina is also
accounted for in the description which follows.

As regards the actinal system, in young specimens we find ten large
plates in the continuation of the ambulacral system, spreading laterally so as
to form a continuous ring. The space between the inner edge of these
plates and the teeth is filled with small plates irregularly arranged. The
ten large buccal tentacles are sometimes reduced to five, one in each ambu-
lacrum being frequently atrophied or much smaller than the other. In these
young specimens, the spheridia first detected in this genus by Duncan *
stand out very prominently between the first and second pair of ambulacral
tentacles. I have only observed one in each ambulacral area in the smaller
specimens; in older ones, we find sometimes as many as three at the base of
the ambulacral area. The spheridia of the younger Saleniz are nearly
hemispherical with a rather long peduncle; in older specimens, they become
more ellipsoid, and are supported upon a comparatively shorter stem.

The primary spines of the youngest Saleniw are very remarkable; the
short, sharp spiny processes of the main shaft, which have been figured as
characteristic of the primary spines of Saleniaw, are in these specimens
replaced by long, slender, curved filiform processes, arranged on each side
of the shaft, and equal in length three times the diameter of the shaft.

* Ann. and Mag. of Nat. Hist., XX. 70.

20 SALENIA VARISPINA.

These delicate processes appear, however, to be soon either worn off or
broken, as in specimens measuring from 2 to 3 mm. in diameter we generally
find only an occasional primary spine still retaining the filiform processes, or
a trace of them. As the spines become older, these processes are little by
little changed to the sharp spiny processes figured as characteristic of S.
varispina. The primary spines of these young stages are also marked for the
single prominent verticillation formed near the base of the shaft by the some-
what stouter filaments of that portion of the radiole.

The young spines found on the small primary tubercles near the abacti-
nal system on the ambulacral and interambulacral areas have a striking
appearance. They recall somewhat the fan-shaped, short spmy radioles
found on the test of very young specimens of Strongylocentrotus; they also
recall the peculiar umbrella-shaped spines of Aceste, and of some deep-sea
Ophiurans. The primary spines, when the shaft has as yet but a single pair
of filaments, could readily pass for modified pedicellariz ; they also resemble
the hook-like appendages of the Ophiurans. In the next stage the radioles
carry from four to five processes, when the central part of the shaft begins
to increase in length; with this increase commences also the formation of
the filaments, so characteristic of the large primary interambulacral spines
of the young stages. The primary interambulacral spines are usually simi-
lar, but shorter, slender-pointed radioles, with from six to eight processes and
a ring of filaments near the base of the shaft. In the youngest stages there
are as yet no papillze; these appear only later, in larger specimens, and at
first show no trace, in the interambulacral areas, of their regular Cidaris-
like arrangement round the base of the primaries, as in the older stages.
The papillae when they first appear are short slender-pointed spines, with
short, sharp processes, covered by lines of pigment-spots of dark violet.
With the growth of the test these papillz become club-shaped, curved,
and finally flattened and fan-shaped, as they appear in the older Salenizx.
The papille of the anal plates are articulated in the older specimens; at
first they are sessile, like the embryonic spines (club-shaped sessile papill)
covering the plates of the genital ring; with the increasing size of the
young Salenia they resemble more the coronal papilla. These abactinal
sessile papillx are interesting, as they develop exactly as do the embryonic
spines in young Echini, from the general granulation of the plates; but
they remain, as in the Arbaciadz, always sessile.

As I have stated, the genital openings are not yet formed in young speci-

SALENIA VARISPINA. 21

mens, and in the older ones there seems to be considerable variation in the
position of the madreporic body ; so that the position of the madreporic
genital can certainly not be taken as expressive of any generic value in this
family, if we are to judge by the recent species. It is not uncommon (five
specimens) to find two genital plates which carry traces of the madreporic
body ; and though the right genital is the one which is most commonly the
madreporic, yet in the first specimen of this species of Salenia described it
was the left genital plate which carried the madreporic body. This induced
Duncan * to refer this species to Peltastes.t

The crenulation of the tubercles can be traced in the earliest stages ex-
amined, but its distinctness varies greatly in different individuals. It is quite
distinct in the large primary tubercles near the abactinal region, it becomes
indistinct near the ambitus, and at the actinostome the tubercles are smooth.
The large primary pedicellaria, both in the ambulacral and interambulacral
areas, are not numerous. We do not find more than two large, short-
stemmed, long-headed, slender-pronged pedicellarix in each of these areas.
The others, very numerous, are quite small, short-stemmed, stout-headed
pedicellaria. In the ambulacral system these small trifid pedicellarix are
thickly placed throughout the area; and in specimens measuring 7 or 8 mm.
in diameter there are six or seven similar pedicellariz in each of the large
buccal plates of the actinostome.

The plates of the actinostome are more numerous than in S. Paétersoni,
and are not as regularly arranged asin that species, in which the acti-
nal imbricating plates resemble the actinal plates of the Cidaridz, both in
their regular arrangement and in forming the continuation of the ambu-
lacral and interambulacral coronal plates on the actinal membrane. In a
specimen of S. varispina measuring 7 mm. in diameter, there are four or
five concentric rows of actinal plates between the large buccal plates and

* Ann. and Mag. of Nat. Hist., XX., 1877.

+ This species is retained in the genus Salenia, although Dr. Duncan has proposed to remove it to
Peltastes. As I have already stated in the Revision of the Echini, and in the Bulletin of the Museum
(L., No. 9), when first describing this species, it differs somewhat from Salenia proper, but it does not seem
to me to belong to the group of Salenidee with which Peltastes is associated, in which the suranal plate is
placed directly opposite one of the genital plates, while in all the recent Salenidze thus far described
they at least all agree in having an ocular plate opposed to the median line of the suranal plate, the
adjoining genital plates uniting just in front of this imaginary median line so as to separate the ocular
plate more or less from the anal system. (Vide A. Agassiz, Revision of the Echini ; 8. Lovén, Echinotdées ;

M. P. Duncan, Ann. and Mag. of Nat. Hist., 1877, 1878; Wyv. Thomson, Voyage of the Challenger;
A. Agassiz, Echinoidea of the Challenger.)

22 PODOCIDARIS SCULPTA.

the actinal edge of the test. In a specimen of S. Padtersoni, measuring 14
mm. in diameter, we find only two or three rows. The granulation of the
actinal plates is coarser in S. varispina than in S. Pattersoni.

The gills in specimens measuring 7-8 mm. in diameter are well developed
as a short five-forked appendage covered by few pigment cells. In smaller
specimens measuring 3 mm., the gills only fork once.

The more we examine the Salenixw, the more we are inclined to consider
the group as holding a position intermediate between the Cidaridze and
the Echinidz. For while the general structure of the coronal plates of the
actinal and abactinal system, of the spines, and of the papilla, recalls the
Cidaride, yet the structure of the teeth, the presence of gills with actinal
cuts for their passage, and the existence of spheeridia, are all features which

associate them with the Echinide proper.

Arbacia punctulata Gray.

Yucatan Bank. 14-84 fathoms.

Podocidaris sculpta A. Ac.

Off Morro Light. 250-400 fathoms.

It is not out of place while speaking of Podocidaris to call attention to
the remarkable genus Tiarechinus of Neumayr,* one of the most character-
istic embryonic genera I know. ‘This diminutive Sea-urchin from the Trias
of St. Cassian represents the young stages of Podocidaris at a time when
neither the abactinal system nor the plates of the mterambulacral area have
become specialized. The whole abactinal part of the test appears from the
figures of Neumayr to be still in the condition preceding the division of the
abactinal system into an anal system and a genital ring, before the formation
of the plates of the anal system or the division of the anal ring into its
component parts. There are very faint indications of what I take to be the
dividing lines between four genital plates in the figure of Neumayr. The
actinal surface, on the contrary, is far more developed; the large primary
tubercles of the interambulacral areas, and the structure of the ambulacral
system, agree most strikingly with the condition of the actinal surface of
young stages of Podocidaris and Arbacia. Compare the figures I have given
in the Revision of the Echini, Plates IV., V., and Figs. 68, 69, p. 734.

* See the figure given in Plate II, Vol. LXXXIV. 1 Abth. p. 169, Sitzungsb, d. K. K. Akad. d.
Wiss. Math. Nat. Cl., Wien, 1882.

CQELOPLEURUS FLORIDANUS.

bo
[S)

* Podocidaris scutata A. Ac.

Podocidaris scutata A. Ac. Bull. M. C. Z, VIIL., No. 2, p. 72, 1880.

Off Santa Cruz. 580 fathoms.

Only one specimen of this species was collected. It is much larger
than either of the others of the genus. Test depressed, remarkable for
its large abactinal system. The whole abactinal surface of test covered
by small, distant, fine, slender fixed spines contrasting with the correspond-
ing coarse granulation of P. scu/pla; fewer large primary tubercles close to
the ambitus on the actinal surface. Actinal membrane entirely covered by
prominent imbricating plates; five anal plates, as in P. prionigera, to which

it is most closely allied. Test light grayish brown when alive.

Ceelopleurus floridanus A. Aa.

Lat. 23° 52’ N., Long. 88° 5’ W. West India Islands, — Barbados. 56-1,323 fathoms ; most
abundant from 100-200 fathoms. :
For other localities, see Bull. M. C. Z., V., No. 9, p. 188, 1878; VIII., No. 2, p. 73, 1880.

PUV ie PR Vide

Many of the specimens of this species dredged in the Caribbean, off the
Windward Islands, are much larger than the small specimens from which the
species was first described. (PI. VII. Fig. 1.; Pl. VIII. Figs. 1-6.) Quite a
number of specimens measured 18 mm. in diameter and a few 28 mm. This
species, however, does not seem to attain the size of the large C. Maillardi.

When alive it is most brilliantly colored, the test varying from a rich light
chocolate in the interambulacra to the brilliant orange or yellow ambulacral
areas. The primary radioles vary greatly in color, from a delicate straw,
often nearly white, to a bright carmine or orange, the base of the spines
being usually colored and the shaft more or less irregularly banded.

On Plate VIII. are given figures of specimens of different sizes, show-
ing the changes they pass through due to growth. The larger specimens
(Pl. VUI. Figs. 1-6), when compared with specimens of (@. Muillardi of the
same size, show that the Florida species differs from it in having a larger
anal system, in the shape of the genital and ocular plates, which is quite
different, being nearly triangular in the Florida species, in having a much
wider bare interambulacral area, and comparatively larger primary ambu-
lacral tubercles, concentrated nearer the ambitus; these tubercles do not
extend to the genital ring, as they do with C. Mail/ardi in specimens of the

same size.

24 ASPIDODIADEMA.

The deep pits at the base of the median ambulacral area are larger and
more numerous than in the Indian species. (Pl. VII. Figs. 2, 3, 5.) The
most striking features due to changes of growth are the comparatively late
period at which the genital pores are developed, even specimens measuring
11 mm. in diameter (Pl. VIII. Figs. 7, 8) showing no trace of such openings.
The genital plates of earlier stages are markedly pentagonal (Pl. VIIL Figs.
11, 12, 15, 18); the granulation of the anal edge of the genital plates is
a character not found in the younger stages. In these young stages the
primary tubercles extend also but little above the ambitus. (Pl. VIII. Figs.
7,11, 15.) In Figure 15 the primary interambulacral tubercles are limited to
the actinal surface, and the primary interambulacral tubercles extend at first
but little towards the abactinal part of the ambulacral area. Compare Plate
VIII. Figs. 7, 11, 15, and Plate VIII. Fig. 1, with their corresponding profile
figures. The resemblance of these young stages of Coelopleurus to some of
the Cretaceous and Jurassic Echini, such as Tiarechinus, ete., is very striking.

The tendency to breaking up of the anal plates already noticed in some of
the species of Arbaciadz is shown in some of the younger stages by the ill-
defined subdivision lines, such as are represented in Plate VIII. Figs. 15, 18.

The function of the ambulacral pits of this genus I have been unable to
ascertain. The sutures present no trace whatever, in the specimens I have
examined, of the remarkable dovetailing observed by Duncan in the pitted

Temnopleuride.

Diadema setosum Gray.

Littoral to 115 fathoms. Florida and West India Islands.

ASPIDODIADEMA A. Ae.

A marked feature of this genus is the nearly uniform size of the secondary
radioles, both in the ambulacral and interambulacral areas. This charac-
ter is a structural feature which Aspidodiadema has in common with the
Cidaridx in addition to their similar abactinal system, to the structure of
the ambulacral areas, etc.; features to which I have already called atten-
tion in the Preliminary Report of the Challenger Echini,* and in the final
Report (p. 64).

I did not notice while examining the Challenger species of the genus

* Proc. Am. Acad., XIV. 199, 1879.

ASPIDODIADEMA ANTILLARUM. 25

a remarkable and interesting type of pedicellaris, which in A. Jucobyi are
quite large and numerous, and are found scattered over the whole of the
abactinal part of the test, especially in the ambulacral area. These are
sheathed pedicellariz, if I may call them so. The shaft consists of a long,
slender radiole, distinctly articulated, surrounded by a huge fleshy sheath,
swelling out into three large bags on the sides, covering a little more than
half the length of the shaft. This sheath extends from the base, where it
covers the articulation, to the extremity of the pedicellarix, at the tip of
which is placed a small head enclosed within this sheath. The sheath at the
extremity expands into a three-lobed cupuliform tip. These pedicellarix re-
call at once the remarkable sheathed secondary spines which I have described
in Asthenosoma Grubei, they form an additional link in the chain, proving that
pedicellarize are only modified spines. The diminutive heads of these pedi-
cellarix, if completely resorbed, would leave us a sheathed spine identical
with the sheathed spine of the Echinothuriz; the existence in that family of
club-shaped primary spines, as in Phormosoma bursaria, the tip of which is still
sheathed to a certain extent, shows how close is the relation of the sheathed
spines to true pedicellariz.

How far this sheath is analogous to the peculiar gland discovered by
Sladen * in some of the types of pedicellariz, I am unable to state positively
at present, but I am inclined to consider it as a modification of this gland.
If this be so, the sheathed pedicellariz are only an extreme modification
of the simple extension of the muscular system of the test over the shaft of
the spines, and over the stem of the ordinary type of pedicellarie ; this
extension being either modified into a sheath covering the whole of the sec-
ondary or primary spines, or merely a part of the shaft; or into a gland; or
into a sheath, such as we find it in Aspidodiadema and the Echinothurix.

* Aspidodiadema antillarum A. Ac.

Aspidodiaiema antillarum A. Ac. Bull. M. C. Z., VIL, No. 2, p. 73, 1880.
Aspidodiadema microtuberculatum A. Ac. Bull. M. C. Z., V., No. 9, p. 188 (non Chall.
Echinoidea).
Southeast extremity of Cuba, Santa Cruz to St. Vincent. 451 to 1,568 fathoms ; most abun-
dant between 400 and 800 fathoms. : :

PUT.
The genital ring of A. andtillarum is comparatively larger than that of A.
Jacobyi. The plates of the genital and ocular system are of nearly uniform

* W. P. Sladen, Ann. and Mag. of Nat. Hist., August, 1880.

26 ASPIDODIADEMA ANTILLARUM.

size ; the former carry larger miliaries than the latter; the ocular plates are
somewhat pentagonal, while the genital plates appear more rectangular with
rounded corners.

The anal system is covered with minute irregularly arranged plates; those
immediately surrounding the anal system are larger, and in older specimens
soldered together to form an irregular calcareous ring round the opening.
This ring carries larger miliaries than the other anal plates. The anal tube
itself extends as a sort of proboscis beyond the general level of the anal
system. It is strengthened by delicate longitudinal calcareous plates. In
A. fonsum we find six plates nearly covering the anal system; in A. iicrotuber-
culatum there are a number of smaller plates arranged irregularly round the
anal opening.

The actinal system is strengthened by ten large buccal plates, as in A.
microtuberculatum, covering nearly the whole of the actinostome. The gills
appear in the youngest specimen | have examined (3.5 mm. in diameter) as
one-forked digits; they do not even in larger specimens take a great develop-
ment, judging from alcoholic specimens.

We do not find in younger specimens any marked differences from the
adult in the structure either of the actinal or of the abactinal system. The
primary spines are proportionally larger and longer, but with the exception
of the smaller number of coronal plates the differences due to growth do not
seem to be important.

The sphzeridia of this species when fully grown are large, globular, short-
stemmed ; they are placed mainly in the abactinal region of the test, but are
also found near the actinostome and scattered over the whole length of the
ambulacral system. Their number varies from two to four, and sometimes
as many as six are found in each area.

The pedicellarix are similar to those previously described as characteristic
of the genus; they are either long narrow-headed and long-stemmed, or
short-headed and stout-stemmed, or short-stemmed and pyramidally headed ;
the last are not numerous. The sheathed pedicellariz are smaller and com- .
paratively more slender than those of A. Jucobyi, the shaft is very slender,
and the head quite diminutive; the sheathed pedicellariz are most numerous
in the ambulacral area above the ambitus near the abactinal region; those
of the interambulacral areas are slightly larger and far less numerous.

In a specimen measuring 11 mm. in diameter, there are six interambulacral
plates; in one measuring 7 mm. there are five. The secondaries and miliaries

ASPIDODIADEMA JACOBYT. 27

are less numerous in this species than in A, sicrotuberculatum ; it also differs
from it in having three or four ambulacral plates (in the median region of
the test) to each interambulacral plate, while there are no less than five or
six in A. microtuberculatum. The proportions of the spines to the test and the
general appearance recalls more A. donswm, while the coloring when alive
is more that of A. microtuberculatum, with a light violet or grayish pink test
and the spines of the same tint but lighter. The primary spines are slender,
as in A. ¢onsum, but they are more curved than in that species. The abac-
tinal part of the test of A. anfillarum is more flattened (Echinostrephus-like )
than is the case in either of the species collected by the Challenger.

The largest specimens of this species collected did not measure more than
15 mm. in diameter.

In a specimen measuring 7.5 mm. in diameter, the anal system measured
3 mm., the abactinal 5 mm., and the actinal 3.75 mm. in diameter; the height
of the test measured 5.75 mm.

In a specimen measuring 11 mm. in diameter, the anal system measured
3.6 mm., the abactinal 6.50 mm., and the actinal 5.50 mm. in diameter; the
height of the test measured 6 mm.

* Aspidodiadema Jacobyi A. Ac.
Aspidodiadema Jacobyi A. Ac. Bull. M. C. Z., VIIL., No. 2, p. 74, 1880.

Cayman Brac, Lesser Antilles. 95 to 297 fathoms.
Pr XS

The largest specimen of this species collected by the Blake measured

32 mm. in diameter. As in A. microtuberculatum, the primary spines are
rather stout, curved, and comparatively short, they are somewhat more
closely packed than in that species, from the greater number of primaries in
the interambulacral areas, a specimen measuring 28 mm. in diameter having
11:12 primary tubercles. The miliaries are more distant than in that spe-
cies, forming a belt of distinct irregularly arranged miliaries in the median
interambulacral space. We find in this species, as in A. fonsum, large pri-
mary ambulacral tubercles, extending nearly to the abactinal system; all
the largest tubercles being placed above the median line of the test, and
gradually increasing in size from that point to the abactinal region, much
as they do in Echinostrephus.

There are not more than three ambulacral plates to each interambulacral
plate. The miliaries extend in horizontal lines between the pores, and form

28 ASPIDODIADEMA JACOBYT.

a narrow irregular vertical line, separating the ambulacral from the inter-
ambulacral region. The primary spines of the two areas are similar, those
of the ambulacral areas being smaller and more slender. The secondaries,
though not numerous, are remarkable for their uniform size in both areas,
and their arrangement recalls to a certain extent that of the papille of the
Cidaridxe. In life the test is of a light greenish pink color, the areolas
darker; the secondary spines are of a light pinkish tint, darker at the base ;
the primary radioles yellowish green, with a greenish chocolate base. In
some specimens the test is also of this greenish chocolate color, the spines
more whitish, or tending towards a dirty yellow.

The sheathed pedicellariz are most numerous above the ambitus toward
the abactinal region; the shaft of the pedicellariz is nearly as long as that
of the secondary spines; from their size the sheathed pedicellariz are very
prominent objects on the test.

The actinostome is covered by ten large buccal plates, as in A. xwcrotuber-
culatum and A, antillarum, but these plates form a ring round the actinal open-
ing, leaving a bare ring between them and the edge of the test.

There are eight large elliptical plates round the anal opening, somewhat
as in A. fonsum, but having a larger ring covered by minute plates between
them and the genital ring. The anal plates are closely tuberculated by
miliaries nearly of the same size as the miliaries of the ocular plates; the
genital plates are coarsely and closely tuberculated by miliaries.

Smaller specimens differ from the larger ones mainly in the lighter coloring
of the test and spines, and the more flattened abactinal region of the test,
which loses its peculiar Echinostrephus-like shape as it increases in size,
becoming more regularly arched, as in Amblypneustes. The plates of the
actinal and anal system cover a comparatively larger space in younger
specimens.

In a small specimen measuring about 3 mm., the anal plates appear as
forming close to the genital ring; the difference in size of the genital and
ocular plates is already apparent. The anal proboscis is quite long at that
stage, equalling in length the diameter of the anal system.

In a specimen measuring 28 mm. in diameter, the anal system measured
5.50 mm., the abactinal 10 mm., and the actinal 9 mm.; the height of the
test was 20 mm.; and there were eleven and twelve plates in the inter-

ambulacral areas.
In a specimen measuring 12 mm. in diameter, the anal system measured

ASTHENOSOMA HYSTRIX. 29

3.25 mm., the abactinal 5.50 mm., and the actinal 5 mm.; the height of the
test was 9 mm.; with nine and ten plates in the interambulacral areas.

In a specimen measuring 5 nim. in diameter, the anal system measured
1:25 mm., the abactinal 3 mm., and the actmal 2 mm.; with seven and eight

plates in the interambulacral areas.

Asthenosoma hystrix A. Ac.

Asthenosoma Reynoldsii A. Ac. Bull. M. C. Z., VIIL, No. 2, p. 75, 1880.
Montserrat, Santa Cruz, Barbados. 103-373 fathoms.
=

Pl, XE A ey

The differences which I noticed (Preliminary Report on the Blake Echini,
Bull. M. C. Z., VIII., No. 2, p. 75) in some of the larger specimens of Asthe-
nosoma collected by the Blake, seemed to be of sufficient importance to
separate them from A. /ystrixy under the name of A. Reynolds. A more
careful examination of the large series of Asthenosoma collected by the
Blake has satisfied me that the differences, striking as they appear at
first sight, are merely due to age, and that what I had called A. Reynolds
in the Preliminary Report are only large specimens of A. hystrix. Spe-
cimens measuring about 125 mm. in diameter are figured by Thomson in
the Porcupine Echini, Pls. LXIV., LXV.; and by me in Pl. HU. of the Hassler
Echini (70 mm. in diameter). I have figured on Pls. XIII. and XIV. two
specimens 165 mm. in diameter, showing the features characteristic of the
largest A. Reynoldsii collected, which measured about 170 mm. in diameter.

In the smaller specimens, less than 70 mm. in diameter, the coronal plates
of both areas are relatively narrower than in larger specimens, and while
the general arrangement of the primary tubercles does not differ greatly in
specimens of different sizes between 50 and 120 mm. in diameter, in the
ambulacral areas, or in the two areas above the ambitus, yet there are very
considerable differences to be noticed in the interambulacral areas on the ac-
tinal side. We find in larger specimens a third, and sometimes even a fourth,
vertical row of primary tubercles extending from near the actinostome to
above the ambitus. Compare Pl. XIV. Fig. 4, with the figures of Thomson
in the Porcupine Echini, and those of the Hassler Echini quoted above.

The smaller specimens less than 70 mm. in diameter are usually of a
brilliant claret-color, but often of a light pink color with only darker
patches of deep claret on the actinal side; we find larger specimens

30 PHORMOSOMA PLACENTA.

usually of a paler color tending to pinkish brown, with dark claret patches
on the actinal side; these patches often disappear completely, and the test
is then of an ashy light-brownish pink, with spines of a lighter color and of a
greenish tint.

The sharp, small secondary spines which cover the test, as has already
been noticed by Thomson and Moseley, cause very severe pain to the hands
and arms if these urchins are handled carelessly, and nothing can be more
disagreeable than the sharp pain which shoots up one’s arm on rashly taking
hold of these prizes as they are first brought up by the trawl. The after
effects resemble those produced by nettles; the disagreeable feeling often
does not disappear for twenty-four hours.

Phormosoma placenta Wvv. Txows.

Phormosoma Sigsbei A. Ac. Bull. M. C. Z., VIII., No. 2, p. 75, 1880.
Lesser Antilles, — Lat. 41° 29’ 45” N., Long. 65° 4710” W. 154-1242 fathoms.

Pl. XID, Pl. XV: Figs. 3-19.

To the leeward of the Lesser Antilles this species is found between 150
and 400 fathoms. On the east coast, in the Atlantic, it has been dredged
from 810 to 1242 fathoms.

1 owe to Mr. Murray the opportunity of examining an excellent series
of specimens of P. placenta collected by the “Knight-Errant” in the Faroe
Channel. The single specimen collected by Thomson in the “ Porcupine,” and
from which his description was made,* was quite imperfect, and I was misled
in describing this species again under the name of P. Sigsbei from specimens
collected by the “ Blake” in the Caribbean and off the east coast of the
United States as far north as Lat. 41° 30’ N. This species has also been
collected by the U. 8. Fish Commission off Martha’s Vineyard.

In the younger stages of this species we find great differences m the
thickness of the test, and the relative size of the abactinal and actinal sys-
tems as compared with the diameter of the test. We find the same sort
of differences, so marked in Toxopneustes from different localities, as regards
the permanence of the primary tuberculation and the number of principal
vertical rows. The tuberculation of the actinal surface does not differ
greatly in specimens of different size ; but in some specimens the tubercu-
lation of the abactinal surface may be limited to a couple of principal vertical

* Transactions of the Royal Society, Vol. CLXIV. Pt. 2, p. 732, Pls. LXIL, LXIIT.

PHORMOSOMA PLACENTA. 31

rows along the outer edge of the interambulacral plates, or the plates in
specimens of the same size may carry the same vertical rows nearly to the
apical system, but placed in the central part.

This arrangement, together with the greater thickness of the test, gives to
these specimens a very different facies, closely resembling in the arrange-
ment of the tubercles P. rigida and other small Echinothuriz, which, when
writing the Report on the Echini of the Challenger, I could not refer to any
of the species collected by that expedition.

The color of the specimens with a thick test is of a deep claret, while
usually the majority of the specimens of P. placenta with a thinner test are
of a brick color, or of a yellowish orange, darker on the actinal side, and
near the ambitus on the abactinal side, and becoming quite light-colored,
either pinkish or yellowish, towards the apical system.

In the youngest specimen of Phormosoma collected by the Blake,
measuring 8 mm. in diameter, the plates of the actinal system have
already assumed the characteristic arrangement of the adult, although there
are as yet but three rows of imbricating plates. We do not find in this
species, as in two of the species of the Challenger collection (P. tenuis and
P. wranus ? Challenger Echini, Pl. XVIII°. Figs. 7, 12), that the buccal ten-
tacular plates differ in size from those following them, recalling the general
arrangement of the buccal plates of young Echinidew proper. On the con-
trary, although the Blake specimens were no larger than the correspond-
ing stages of the Challenger species, they show that in this species of
Phormosoma the characteristic structural features of the Echinothurix are
already developed. This, as I have already shown, we also find to be the
case in young Cidaride. It thus appears that in some of the species of
Echinothuriz the Kchinid features of the actinostome seem to be retained
much longer than in others, and do not even seem always to be developed,
if we may judge from the young stages of the West Indian Phormosoma
here described.

The mode of formation of the coronal plates, and of the actinal and
abactinal systems, is well shown in the series of the young of Phormosoma
I have had occasion to examine. As I have suggested before, the Kchino-
thurize are the most embryonic of the Echini. The coronal plates when
they first appear, somewhat indistinctly defined, in young specimens measur-
ing about 8 mm. in diameter, show very clearly that there is no special line
of demarkation to be drawn in the young stages between the abactinal and

32 PHORMOSOMA PLACENTA.

coronal system. From seven to nine of the coronal plates appear at the
same time, the division line of the sutures being traced with difficulty in
young specimens measuring 8 mm. in diameter, but becoming well defined
in somewhat larger specimens of from 17 to 20 mm. in diameter.

In the youngest stage (§ mm. in diameter) the actinal plates are separated
from the coronal plates, and are developed, as I have shown, in the same
manner as the imbricating plates of the Cidaridx, independently of the
coronal plates; new plates forming on the distal surface of the actinostome,
which are intercalated between the old plates and the coronal plates. On
the abactinal system, on the contrary, while the plates of the genital ring
are well defined and seem to be distinctly separated from the coronal plates,
yet new interambulacral plates are not added independently, as in the
ambulacral system, and as in the interambulacral system of other young
Echinoids where the genital ring remains permanently closed. The new
interambulacral plates are found to be pushing out from the plates of the
anal system on each side of the genital plates. As the ocular and genital
plates of the genital ring become separated, with increasing size, the addi-
tional anal plates formed in the intervening spaces are pushed out, and
become a part of the abactinal portion of the interambulacral area.

This mode of growth of the interambulacral areas combines to a certain
extent the modes of formation of the plates of the abactinal system of young
Starfishes and of young Ophiurans, in which the interambulacral plates are
derived directly from the plates of the abactinal system. This shows a far
closer relationship between the young of some of the Sea-urchins of the
present day with Starfishes and Ophiurans on the one side, and Holothurians
on the other, than had been suspected formerly. The plates are formed by
a close-meshed reticulation of small, comparatively thick Y-shaped rods,
with bare interstices for the joints of the plates. The tubercles of the
miliaries and of the pedicellarix are built up by a close accumulation of
these meshes, forming what appears a fine granulation. The small tuber-
cles are formed by the clustering together of five or six larger cells,
arranged concentrically round a central space, which eventually forms the
perforation of the tubercle; as this increases in size, the mammary boss is
gradually formed from a similar concentration of the limestone meshes,
and finally the edge of the boss becomes indistinctly crenulated. The
tubercles, when arrested in their development in any one of these success-
ive stages, form what are known as miliary, as secondary small primary,

and as primary tubercles.

PHORMOSOMA PLACENTA. 33

The characteristic pedicellarix of the genus appear early. A few pedi-
cellariz of the different kinds noticed in the adult of this species are found
in young specimens scattered over the test, mainly on the actinal surface.
Spheeridia are also present in these youngest stages; they are found extend-
ing from the plates of the actinal membrane, close to the teeth, to the
abactinal area, along a line at the base of the ambulacral tentacles, usually
one for each tentacle ; in older stages they are rarely seen, being probably
broken off. If the Cidarids possess spheeridia, we may perhaps look for
them, in the young stages, on the imbricating plates of the actinal mem-
brane.

In the early stages of growth the plates of the genital ring are in contact
along their edges; as the young become older, the space between the ocular
and genital plates increases, and they become separated by a number of anal
plates. The anal system is at first, in the youngest specimens, covered by
plates of a nearly uniform size, with only a few smaller ones occasionally
intercalated between them; with increasing size the number of these inter-
calated plates becomes larger, and the original larger anal plates are then
separated by a greater number of accessory ones. The large original plates
retain their prominence in later stages of growth, and, much as the single
embryonic anal plate of young Kchinoids, can easily be traced, in older
stages, among the other anal plates of subsequent growth.

I do not quite understand Neumayr’s statement that in the young Cly-
phostomes the anal plate is first formed, and that the plates of the genital
ring are formed later and become detached from it laterally. That certainly
is not the case in any of the young Echini I have had occeasion to examine.
While undoubtedly the anal plate is the first plate to appear, yet the genital
and ocular plates are formed outside and independently of it, just as much
as in the young stages of Comatula the basalia arise independently of the
dorso-central plate, and just as independently as the same plates arise inde-
pendently in the young Starfishes. See my Embryology of the Starfishes,
and Lovén’s figures.

As I have previously shown in speaking of the apical system of the
Palechinide and Echinothurie, the plates of the apex of the anal system
hold a very different relation to the interambulacral system in those groups
from what they do in the Echinide, in which the genital ring is closed, a
condition of things which begins only with the Echini of Mesozoic times,
and is represented in the Cidaride by their having still a number of plates,

34 PHORMOSOMA PLACENTA.

no one of which becomes more prominent than the others. This is the
case only in the Salenize and in the young stages of Echmide, and does
not seem to have reached as yet its greatest development in the Echini
of the present period. Unfortunately there is no Pluteus of Echinus figured
in a stage showing the first appearance of the calcareous rods. Such an
observation might throw very important light on the homology of the
Echinoid apical system.

The apical system of two specimens of Asthenosoma varium, figured by
Ludwig,* is interesting, as it is the only species of Echinothuria in which the
genital ring is closed, connecting the structure of the apical system with
that of the Diadematidxe proper. It is true that the specimens of which
Ludwig figures the abactinal system were not fully grown, and were much
smaller than the specimens of the allied species A. Grube, figured in the
Echini of the Challenger Report, Plates XV.—XVIL., in which the genital ring
is less open than in any other species of Asthenosoma I have had occasion
to examine. It will be seen, on examining the figures of young Echinothurize
in the Report on the Echini of the Challenger, that, while the plates of the
genital ring are placed nearer together in the young stages than in older
specimens, yet they are more or less separated even in the earlier stages by
the anal plates, which force their way between the ocular plates and the two
sides of the genital plates in the two zones of the apical part of the inter-
ambulacral area.

In the early stages (S mm. in diameter), the ambulacral tentacles are
arranged in a single vertical row, extending from the actinal opening to the
ocular plate. It is only in specimens measuring from 28 to 40 mm. in
diameter that we can find the characteristic generic arrangement of the
ambulacral tubes. In specimens measuring from 17 to 25 mm. in diameter,
the actinal imbricating plates have increased to four, the gills are well de-
veloped, and the final arrangement of the primary tubercles both of the
actinal and abactinal surface is indicated in a general way on the plates
adjoining the ambitus, in both the ambulacral and interambulacral areas.
The marginal fasciole can already be made out in specimens measuring
about 28 mm. in diameter; in specimens of 50 mm. in diameter it is quite
prominent.

The lapping of the coronal plates takes place at a later stage of growth
than that of the plates of the actinal membrane; the latter are distinctly

* Zeitsch. f. Wiss. Zool., XXXIV., Pl. II.

PHORMOSOMA URANUS. 35

imbricated towards the actinal opening from their first appearance. It is
only when the young Phormosoma has attained a diameter of from 35 to
45 mm. that the lapping of the coronal plates of the ambulacral and inter-
ambulacral areas becomes distinct.

As in the young of other Echini the genital and ocular plates are not
perforated in the youngest stages, nor can the madreporic genital be dis-
tinguished from the others, owing to the similarity of the calcareous meshes
of the young genital plates to the openings of the madreporic canal. In
somewhat older stages, however, the madreporic genital is readily distin-
guished from the others (in a specimen measuring 20 mm. in diameter).
This is also the stage at which the other plates of the abactinal system
begin to show the perforations for the genital and ocular pores.

It is interesting to compare the structure of a young Astropyga (Pl. XV.
Figs. 1, 2), measuring 13 mm. in diameter, with these young stages of Phor-
mosoma (Pl. XV. Figs. 5-19). This comparison clearly brings out the strik-
ing difference between the structure of the actinal and abactinal systems
in the Diadematide and Echinothurie. In Astropyga the genital ring
always remains closed, and the actinal system is provided with the ten
large buccal plates characteristic of young Echinide, and with an irregular
imbricating system of small imperforated plates forming a regular ambula-
eral and an irregular interambulacral series. The peculiar forked band of
pigment cells of the abactinal part of the coronal plates so characteristic
of Astropyga seems to be the remnant of the pigment spots which are
irregularly scattered over the test of young Echinothurix, and which in the
Diadematide have a regular arrangement. These large pigment spots are
eminently an embryonic character, for we find the test of the young stages
of regular Echini thickly covered with large prominent patches of pigment.

Phormosoma uranus Wyv. THoms.

Phormosoma Petersii A. Ac. Bull. M. C. Z., VIII., No. 2, p. 76, 1880.
Lesser Antilles, —Lat. 39° 45’ 40” N., Long. 70° 55’ W. 399-1224 fathoms,

Pie PE OEE

Thomson figured in the “ Voyage of the Challenger” (I. p. 146, Fig. 33,
p- 147, Fig. 34) a small specimen of Phormosoma which he called P. wranus.
It differed very strikingly from specimens of a closely allied species collected
by the Blake, which I had provisionally named P. Petersi. The principal

36 PHORMOSOMA URANUS.

structural feature of P. wranus consists in the extreme tenuity of the test,
and in the fact that “there is but little difference in character between
the upper and lower surfaces of the test, and the species thus holds a place
intermediate between the genera Phormosoma and Calveria.” While this is
true of specimens of the size of that figured by Thomson, and of younger
ones, it does not hold good for larger specimens, in which we find that
the larger tubercles of the actinal surface are comparatively small, and not
limited to a narrow band of the actinal and abactinal surfaces immediately
adjoming the ambitus. But, on the contrary, in older and larger speci-
mens the primary tubercles of the actinal surface become larger with age,
extending at the same time over a greater portion of the actinal surface
from the ambitus towards the actinostome, as in other species of the genus
Phormosoma. Of P. wranus I had on former occasions only the opportunity
of examining the very imperfect specimen described by Thomson. Since
that time Mr. Murray has sent me for examination the Echini collected by
the Knight-Errant in the Faroe Channel. Among them was a specimen
of P. uwranus intermediate in size between the smaller specimen described
by Thomson and the larger and older specimens collected by the Blake
from the West Indies and off the southern part of the Atlantic coast of
the United States, which I had named P. Pefersii. A renewed comparison
of the specimens with this additional material plainly shows that the differ-
ences which had been noticed between them were merely due to age, and
that in this species the great development of the large primary tubercles
of the actinal surface takes place at a late period of growth. The abactinal
system also seems to increase more rapidly in size in proportion to the rest
of the test, as the specimens grow larger; so that in younger specimens
the abactinal system is relatively smaller compared with the diameter of the
test than in the larger ones. The specimens collected were all of a brilliant
claret-color.

Echinometra subangularis Dzsmt.

Florida, West India Islands. Littoral to 250 fathoms.
’

/ Ce te 2
G, MrwlA ra hy

Strongylocentrotus Drobachiensis A. Ac.

(East Coast of United States,) Lat. 41° 30’ N., Long. 66° W., in 73 fathoms.

TEMNOPLEURID. 37

TEMNOPLEURID &.

Duncan * has, in interesting articles on the pits and sutures of Temno-
pleurus and on the structure of Pleurechinus, called attention to the im-
portant differences existing between the Temnopleuride of the type of
Temnopleurus proper and its allies, and such genera as Temnechinus and
Trigonocidaris, which have been associated with them.

He proposes to place on one side the genera Pleurechinus, Temnopleurus,
Salmacis, and Amblypneustes, which have true pits, and on the other side
the genera Temnechinus, Trigonocidaris, Paradoxechinus, and Glyphocy-
phus, which have raised ribs.

The structural difference so well pointed out by Duncan is an important
one ; he says he was unable to find, in the specimens of Temnechinus from
the Crag which he examined, any trace of the remarkable “deep inward
undermining or penetrations of the test’ of Temnopleurus. The specimens
of Temuechinus maculatus of different sizes which I have examined show
no trace of pits, nor of this system of dowelling at the junction of the
plates. I have also again examined specimens of the recent Trigonocidaris
albida, and do not find in that species either the sunken pits of Temno-
pleurus proper or the dowelling.

Duncan and Sladen ¢ have figured in the fossils of Western Sind two other
genera closely allied to Trigonocidaris: Dictyopleurus and Arachnopleurus,
in which the grooved and pitted ornamentation of the test is produced
entirely by ribs and elevations. The peculiar structure of the ornamentation
of the genus Progonechinus shows how difficult it may become to maintain
the distinction suggested by Duncan.

I had already called attention in the Revision of the Echini, p. 286, to
the character of the ornamentation of the test of some of the Temnopleuride,
and to its probable derivation from a more simple type of ribbed ornamen-
tation, such as is formed by the radiating arrangement of miliaries and
secondaries round the primary tubercle of some of the Triplechinide and

* P. M. Duncan, On some Points in the Morphology of the Test of Temnopleuride, Journal Linn,
Soc, London, 1882, Vol. XVI. p. 343. On the Genus Pleurechinus, L. Agassiz, Journal Linn, Soe.
London, 1882, Vol. XVI. p. 447.

+ Mem. Geol. Survey of India, Ser. XIV., Vol. I, The Fossil Echinoidea, Fascicul. II. Cal-
cutta, 1882.

8 TEMNOPLEURIDZE.

Oo

Arbaciade. The next stage being the formation of low radiating spokes
round the primaries formed by the running together of flattened miliaries or
secondaries. From this type of ornamentation the passage is an easy one
to the marked and prominent ridges of Trigonocidaris, Dictyopleurus, and
the like. But,as I have shown when speaking of the changes due to growth
in young Temnopleuride, the presence of pits and sutures is a feature only
developed with age, and the transition is insensible between the types in
which the pits and sutures are formed by the modification of a flat surface
due on one side to the thickening or elevation of nearly the whole plate, or,
on the other, of only a portion of it. This still leaves, however, as charac-
teristic of the Temnopleuridx and their nearest allies as limited by Duncan,
the remarkable dowelling of the sutural faces.

The peculiar sunken pits of the Clypeastroids extendmg around the
primary tubercles reach deep into the thickness of the test; they are not
to be regarded as merely sunken areolas. In some of the Nucleolidz we
have a similar sunken area round the primaries; on the actinal side, round
the actinostome of such genera as Rhynchopygus, these pits are independent
of the tuberculation, and form very deeply sunken and irregularly shaped
grooves in the thickness of the test. In Goniocidaris, another genus in
which we have pits and sutural bands, they are not deep, and do not extend
into the thickness of the test.

Temnechinus maculatus A. Ae.

Lat. 26° 31’ N., Long. 85° 53’ W. Lesser Antilles, Florida. 73-229 fathoms.
For list of Stations, see Bull. M. C. Z., V., No. 9, p. 189, 1878; VIII., No. 2, p. 76, 1880.

This species has also been dredged by the U. S. Fish Commission off New-

port in deep water.

Trigonocidaris albida A. Ac.

Lat, 24° 15’ N., Long, 82°13’ W. Florida, Lesser Antilles. 124-450 fathoms.
For list of Stations, see Bull. M. C. Z., V., No. 9, p. 189, 1878; VIII., No. 2, p. 77, 1880.

Echinus gracilis A. Ac.

Straits of Florida, West Indies, East Coast of U.S., and as far north as off Martha’s Vineyard,
by the U. S.'Fish Commission. 93-200 fathoms.

-_

ee fprdrive wheres G Y 133 ~- Fo
\/ ’

V

ECHINUS WALLISI.

isk)
io)

| Echinus norvegicus Dvs. o. Kor.
™

Off Newport, in Lat. 39° to 41° N. Very common in 1242 fathoms.
For list of Stations, see Bull. M. C. Z., VIIT., No. 2, p. 77, 1880.

It seems almost hopeless to attempt to distinguish the species of Echinus
known as L. elegans, L. norvegicus, LE. melo, and L. Fleming. While the speci-
mens from the same localities usually vary but little, those of adjoming or
distant localities vary to such an extent that they generally combine more or
less the specific features by which we have become accustomed to separate
the above-named species.

A large series of EF. norvegicus from 1242 fathoms shows but the slightest
possible variation among the different individuals; yet they all have the anal
system which thus far has been considered characteristic of Z. elegans.

The largest specimens I have seen of this species were collected by
the “Porcupine,” but they differ in no marked way from the typical Z.

norvegicus.

A *Echinus Wallisi A. Ac.

Echinus Wallisi A. Ac. Bull. M. C. Z., VIII., No. 2, p. 77, 1880.
Atlantic Coast of U.S., Lat. 31°-41° N., Long. 65°-74° W. 257-1047 fathoms.

This species is evidently closely allied to, if not identical with, Eehinus
Alexandri, subsequently described (1882) by Danielssen and Koren. They
have given a very characteristic and excellent figure of this species in
Plates III. and IV., Figs. 7-16, of Nyt. Mag. for Naturvid., XXXVII. For
their description, see page 294 of the same article. 2. Alezandri was dredged
from a depth of 536 fathoms, Lat. 69° 18’ N., Long. 14° 32”.7 E.

This is a large species allied to £. Plemingii and £. elegans. The test is
somewhat depressed. It is readily distinguished by the close secondary
tuberculation surrounding the primary tubercles, and by the arrangement
of the pairs of pores in sets of two, The primary spines are long and
sharp, like those of H. Flemingii. The anal system is intermediate in size
between that of HL. Flemingii and that of L£. elegans.’ When alive it was of a
brilliant dark reddish pink color, the test of a darker shade than the spines ;
these are darkest at the base and pinkish at the tip. The smallest specimen
collected measured about half an inch in diameter. A fine large specimen
of this species, measuring three and a half inches in diameter, was collected.
It has also been found off Newport by the U. 8. Fish Commission.

40 ECHINOCYAMUS PUSILLUS.

Toxopneustes variegatus A. Ac.

Yucatan Bank, Florida, Lesser Antilles. Lat. 32° 25’ N., Long. 77° 42’ 30’ W. 14-300 fathoms.
For list of Stations, see Bull. M. C. Z., VIII, No. 2, p. 78, 1880.

Hipponoé esculenta A. Ac.

Yucatan Bank, Cuba, Florida, Lesser Antilles. 14-451 fathoms.
For list of Stations, see Bull. M. C. Z., VILL, No. 2, p. 78, 1880.

Echinocyamus pusillus Van Pu.

4

Florida Bank, Florida, Cuba, Lesser Antilles. 98-805 fathoms ; most abundant between 150 and
400 fathoms. ao
For list of Stations, see Bull. M. C. Z., V., No. 9, p. 189, 1878; VIII., No. 2, p. 78, 1880.

An immense number of dead tests of this species were dredged in the
Caribbean, the Gulf of Mexico, and the Straits of Florida. It has not yet
been found to the northward of the Straits of Bemini. The number of
living specimens brought up is small. It is interesting to note, in this
connection, that the dead tests of species of Clypeaster, of Echinanthus,
of Encope, of Schizaster, of Macropneustes, of Agassizia, of Echinolampas,
of Linopneustes, of Toxopneustes, of Trigonocidaris, of Temnechinus, of
Salenia, and of Cidaris, were also frequently dredged, and sometimes in
considerable numbers, This has an important bearing as indicating the
species which are likely hereafter to be preserved as fossils, and shows us
how difficult it may become, even when we have such an abundant and
characteristic Echinid fauna as that of the West Indies, to reconstruct it
from the future fossils. It is also interesting to note that the genera
(except Echinocyamus) of which we so frequently find the dead tests are
the same which have been known as characteristic of the West Indies
since the earliest tertiary. Evidently, except under the most favorable
circumstances, we cannot expect to find represented as fossils the Echino-
thuriz, Pourtalesiz, and many of the Echinidee, which after death readily
fall to pieces, and may be dissolved by the excess of carbonic acid at
great depth before they become protected by a covering of deep-sea
ooze.

CLYPEASTER LATISSIMUS. 41

Clypeaster latissimus A. Ac.

Laganum latissimum Hopi, 1856, Castel Voy. Am. Sud., p. 98 (non Lam.).
Yucatan Bank, Lesser Antilles. Santa Cruz, 248 fathoms ; Dominica, 98 fathoms ; Montserrat,
88 fathoms ; Lat. 18° 12’ N., Long. 64°, 1952 fathoms ; Granada, 92 fathoms.

Pl, XV". Figs. 3,4; Pl. XV’. Figs. 3, 4.

The Blake dredged a number of specimens of the flat Clypeastroids.
With this additional material I have made a renewed comparison of the
species I had been led to unite under the name of Clypeaster subdepressus in
the Revision of the Echini. I am now inclined to recognize three West
Indian species of the genus Clypeaster, all of which had been before de-
scribed on what I presumed to be insufficient data, and from the great
variations I had observed in the shallow-water C. subdepressus of Florida I
was induced, at the time of writing the Revision, to consider these so-called
species as all belonging to the common Florida species. The remarkable
constancy of certain characters, however, in the series I have collected, has
led me to return to the old specific distinctions, and to recognize three
well-marked specific types in the genus.

The typical Clypeaster subdepressus, with a large rosette, a thick rounded
edge, and the test but slightly arched in the petaloid region, and with close,
remarkably uniform tuberculation extending over the whole of the actinal
surface of the test, close to the ambulacral furrows, which disappear in the
tuberculation near the edge of the test. On the abactinal side the whole
surface is covered by a close tuberculation, smaller than that of the oral
surface, and the tubercles are separated by a fine granulation.

The second species, C. dadissimus, is marked for its thin test, and for its
small ambulacral rosette, which does not extend more than half-way from
the apex to the edge of the test; the whole abactinal surface is covered by a
close pavement of minute miliary granulation, with the exception of a small
part of both the ambulacral and interambulacral areas adjoining the apex,
where we find a few large distant primary tubercles. On the actinal side the
tuberculation is very striking ; primary tubercles similar to those of the apex
extend around the edge of the test, as they pass towards the actinostome
diminishing rapidly in size on the ambulacra towards the median part
of the furrow, which is covered by fine miliary granulations. Along the
edge of the furrow there are small primaries passing into larger primary

42 CLYPEASTER LATISSIMUS.

tubercles with three or four still larger primaries towards the outer edges
of the ambulacral plates. The interambulacral plates carry huge primary
tubercles, three or four to each plate, arranged in irregular concentric
rows. These tubercles increase in size towards the central part of the
interambulacral area, and then diminish again in size towards the actino-
stome. The intertubercular space is closely packed by a minute miliary
granulation. The miliary granules of the actinal and abactinal surface carry
short, sharp, straight miliary spines; these are somewhat larger, and curved
on the edges of the furrows and over the petaloid ambulacra. The large
primary spines of the interambulacral areas of the actinal side are long,
stout, curved, slightly spathiform, and recall somewhat for Clypeastroids
the Lovenia type of spines and of tuberculation.

The color of these flat Laganum-like specimens is bright yellowish green
when alive; the large spines are of a lighter yellow color, ‘This species is
undoubtedly the one Hupé referred to Laganwn latissimun.

The third type, which I have figured on Plate XI°. of the Revision, and
described under the name of S/olonoclypus Lavenellii, 1s characterized by
the thick-swollen edge and the high central part of the test, by the large
open petals with the distant pairs of pores, succeeding pairs being about
twice as far apart as in @. subdepressus and C. lalssimus, and by its distant
uniform primary and coarse intertubercular granulation. As in CL subde-
pressus, the granulation covers the abactinal surface uniformly. On the
actinal side it is coarser, more distant, the tuberculation becoming smaller
as it passes into the ambulacral areas, leaving the greater part of the am-
bulacral plates merely covered by a fine miliary granulation.

The figures I have given in the Revision of the Echini as characteris-
tic of the young stages of Clypeaster subdepressus are on Plate XIII. Figs.
10-18; these, however, all belong to the swollen-edge type, C. Ravenelhi ;
the other, Plate XII". Fig. 4, is a young of C. datissimus. An excellent
series of the young stages of C. /alissimus shows that im these very flat
Clypeastroids the needle-like or separate lamellar pillars forming the mner
partitions become united together at their extremity, either simply at the
base or along the whole height of the pillar, so as to form more or less
irregular concentric and dendritic partitions or isolated pillars arranged in
concentric rows.

The structure of the partitions in ©. /afissimus, and the presence of ambula-
cral furrows, show a close relationship between the flat Clypeastroids and the

ECHINARACHNIUS PARML. 45

Laganide.* Among the specimens I have had occasion to examine I do
not find any marked difference due to age in the width of the marginal
edge which is occupied by the pillars. The structure of the test of the
flat Clypeastroids shows that they are closely connected with Conoclypus,
the ambulacral furrows and the teeth specially showing these groups to
have an intimate connection. Kchinolampas, on the contrary, although
superficially more closely related, in reality differs more from Conoclypus
than do the flat Clypeastroids.

Clypeaster Ravenellii A. Ac.

Stolonoclypus Ravenellii A. Ac. Bull. M.C. Z., L. p. 265, 1869.
West Florida Bank. 14 fathoms. Yucatan Bank. 84 fathoms.

PI. XV’. Figs. 1,2; Pl. XV. Figs. 1, 2.

Clypeaster subdepressus Acass.

Florida, Yucatan Bank, Lesser Antilles. 84-1952 fathoms.
For list of Stations, see Bull. M. C. Z., VIII., No. 2, p. 79, 1880.

PY Xe

Echinanthus rosaceus Gray.
Yucatan, Cuba, Lesser Antilles. 14-118 fathoms.

The specimens dredged by the Blake show the usual differences in the
comparative height and length of the test.

Echinarachnius parma Garay. A

Lat. 40° 59’ N., Long. 71° 22’ 30 W. Lat. 41° 30’ N., Long. 66° W. Off Newport. 71-306
fathoms.
For list of Stations, see Bull. M. C. Z., VIIL., No. 2, p. 79, 1880.

The genus Kchinarachnius extends to a greater depth than Mellita. The
former was very common beyond the 100 fathom line north of New York,
and on the George’s Bank, but to the south it was not found at the same
depth, nor were any of the species of Mellita, and but one of Encope,
dredged by the Blake beyond the 100 fathom line in the very districts in
which these genera are the most typical littoral species.

‘

* T would refer also to an article on the Laganide in Ann. and Mag. Nat. Hist., No. 62, for February,
1883. Ido not propose to discuss the statements made by Prof. F. J. Bell.

44 NEOLAMPAS ROSTELLATA.

Encope Michelini Acass.
Yucatan Bank. 14 fathoms.
‘ 7
Echinonéus semilunaris Lam.

Cuba. Littoral to 80 fathoms.

Neolampas rostellata A. Ac.
Florida Bank. 229 fathoms.

PP] XGKEE:

A number of specimens of this interesting genus, of all stages of growth,
having _been collected by the Blake in the Straits of Florida, I am able to
add considerably to our previous knowledge of the genus. As in all Cas-
siduloids, the affinities of the family to the Clypeastroids is more or less
marked. In the young specimens from Florida the changes taking place
in the actinostome, in the ambulacral system, and in the shape of the test,
as well as the structure of the pedicellaria and of the abactinal system, all
show strikingly the close affinities of the family with the Clypeastroids.

In the youngest stage examined, measuring only 2.5 mm. in length, the
test, instead of being globular, as is the case in the Spatangoids proper, is
quite flattened, its outline is elliptical, the anal system is covered by few
large plates, and the general aspect of the young Neolampas at this stage
and in the following one, when it measures about 4.5 mm. in length, closely
resembles the young of some of the true Clypeastroids which I have had
occasion to examine, such as Echinocyamus, Mellita, or Echinarachnius.

On their first appearance the bourrelets and phyllodes are with difficulty
made out, and in the earliest stages the actinostome shows no trace what-
ever of them. The ambulacral suckers are, like those of the Clypeastroids,
provided with powerful suckers near the actinostome, which are but slightly
developed above the ambitus; we find no fimbriated actinal tentacles, even
in the largest specimens collected, measuring 12 mm. in length, so character-
istic of the Spatangoids proper. The bourrelets are well developed in speci-
mens of 10 mm. in length, and in the largest specimen (12 mm. long) they
have become very prominent. The lateral crowding of the ambulacral plates
near the actinostome to form the phyllodes is well shown on comparing
the arrangement and size of the plates as seen from the interior of the test

NEOLAMPAS ROSTELLATA. 45

in two specimens, one of which measured probably 7-8 mm. in leneth, the
other from 10 to 11 mm. The interambulacral spines of the bourrelets are
slender and longer than those of the tubercles of corresponding size in other
parts of the test. The somewhat distant primary radioles, are short, sharp,
slender, and the intertubercular space of the whole test is thickly covered by
secondary tubercles, carrying small, slender, straight radioles, usually having
a slight cup-shaped extremity, which have been well figured by Thomson in
the Echini of the Porcupine Expedition; he has also figured the pedicellarixe
characteristic of this species. The principal large pedicellaria are more
closely allied by their structure to the Clypeastroid than to the Spatangoid
types; in addition to these, there are also in the ambulacral areas more
numerous pedicellarize with short stout stems, quite similar to the secondary
radioles but somewhat more slender, carrying a small trifid head set closely
upon the cup-shaped extremity of the stalk. Minute long-stemmed, small-
headed pedicellariz are found near the actinostome in the ambulacral and
interambulacral areas.

As the test increases in size its outline becomes more angular, the posterior
extremity more elevated, and the Spatangoid features of the genus more ap-
parent. There is, however, even in the largest specimen collected, no trace
of petaloid ambulacra on the abactinal surface; the ambulacra retain as far
as we know their simple embryonic structure. The apical system is compact,
the genital openings are large, the ieft anterior and posterior genitals are
atrophied. This was not the case either in the specimens collected by
Thomson or in those previously dredged off Florida, in which the left
anterior genital pore was wanting, in addition to the odd posterior one. In
a specimen measuring 10 mm. in length there are two or three madreporic
openings in the space between the genital openings. In Thomson’s speci-
mens, which are larger than any I have dredged, there are two such
openings. I was unable to distinguish the line of sutures between the
different genital plates. When covered with spines, the genital openings
are protected by long secondary spines, and genital tubes are seen to
project through the large openings beyond the level of the spines. ‘Two
or three, and sometimes four, spheridia are found near the actinostome
in each ambulacral area.

46 ECHINOLAMPAS DEPRESSA.

Echinolampas depressa Gray.
Yucatan Bank, Lesser Antilles. 82-101 fathoms.
Pl. XVI, Pl. XXIV. Figs. 1-5.

The Blake dredged in the Caribbean a number of specimens of this
species. They are interesting as showing that the important modifications
in the petaloid region of the ambulacral system, which characterize this and
allied species in different stages of growth, make their appearance very
early. In the younger stages I have figured (Revision of the Echini, PI.
XVI. Figs. 6, 7, 17, 18, 19, 21), the early development of the petaloid am-
bulacra and the unequal growth of the different poriferous zones of the
ambulacra are quite striking. In a specimen measuring 57 mm. in longi-
tudinal diameter, the left petaloid poriferous zone of the odd anterior ambu-
lacrum is four pairs of pores shorter than the right. The anterior zone of
the anterior ambulacra is fourteen pairs of pores shorter than the posterior
zone, and the posterior zone of the lateral posterior ambulacra is seventeen
pairs of pores shorter than the anterior zone. In a specimen measuring
45 mm. the difference in the number of pairs of pores between the same
poriferous zones was greater by three in the anterior ambulacra, and less by
four in the posterior ambulacra. This striking numerical difference still
existed in specimens measuring no less than 50 mm. in length (Pl. XVI. Figs.
1, 3, 6), but is by no means constant, the difference between the number of
pairs of pores in the anterior and posterior zones of the lateral ambulacra or
in the right and left zones of the odd ambulacrum sometimes varying from
the ratio stated above as much as four to six pairs. Similar differences in
the length of the zones of the ambulacral petals are known in several recent
and fossil species of the genus. This naturally suggests the propriety of
subdividing the genus Echinolampas. This has been attempted in part
by Bell, who has separated as Paleeolampas a species of Echinolampas with
straight ambulacral zones, and in which the outer rows of pores are the
largest, and form with their rudimentary furrows embryonic petals. De
Loriol has shown the difficulty of taking this character alone as basis for a
generic division ; but it would be convenient were we to take the living types
alone, and subdivide the genus Echinolampas proper into sections, one con-
taining the ovoid forms with distinctly petaloid ambulacra of equal length,

ECHINOLAMPAS DEPRESSA. 47

another containing those in which there is a marked difference in the length
of the poriferous zones of the ambulacral petals, and a third, which Bell has
called Palxxolampas, characterized by the straight apetaloid ambulacral zones.
The differences in the petaloid ambulacra are accompanied by other struc-
tural features, such as the position and outline of the anal system, and the
character of the phyllodes and bourrelets, forming combinations of characters
which a revision of the genus may show justify this subgeneric division.
But as has been already pointed out by Cotteau and De Loriol, such a sub-
division is impracticable if we take into account the numerous fossil species
of Echinolampas. The subdivision of the genus to which Lchinolampas depressa
belongs is also marked by the absence of intercalated plates in the formation
of the phyllodes (Pl. XVI. Fig. 4), and by the prominent apical button
formed (Pl. XVI. Fig. 5) by the madreporic body, much as in Conoclypus.
The characteristic uniform tuberculation of the test of #. depressa is seen in
the different figures of Plate XVI. On the actinal surface there is a narrow
band in the median ambulacral areas towards the actinostome. The abac-
tinal surface of the test is covered by slender radioles; the radioles of
the abactinal region are slightly shorter, increasing in length towards the
ambitus, and becoming somewhat longer on the actinal side. The mili-
ary spines are about a third of the length of the primary spines. When
alive, the spines are of a greenish yellow color; the test, of a dirty yellow
color. It is interesting to note that, of the many fossil species of Echino-
lampas described by Cotteau* from the West Indies, only two, £. Castroi
and FZ. Anguilla, show any marked difference in the length of the poriferous
zones of the petaloid ambulacra.

On Pl. XXIV. is figured the youngest stage of Echinolampas I have seen.
It measures 5 mm. in longitudinal diameter. The apical system is already
eccentric ; but in this stage the ambulacra are simple, showing no trace at
the apex of rudimentary petals. The actinal system is circular, and the
anal system is still on the posterior face of the test; the bourrelets are in
the simplest form possible, a slight swelling of the ambulacral area at the
actinostome, but the tuberculation is not different from that of the other
part of the ambulacra,

* Cotteau, Ann. Soe. Géol, de Belgique, 1881, IX., Pl. Il. Echinides Tertiaires des Isles St. Barthéle-
my et Anguilla, K. Vet. Akad. Handl., B, XIII., No. 6, Pl. 1V., 1875.

48 CONOLAMPAS SIGSBEI.

Conolampas A. Ac.

Conoclypus A. Ac, Bull. M.C. Z., V., No. 9, p. 190, 1878 [non aucet.].

*Conolampas Sigsbei A. Ac.

Conoclypus Sigsbei A. Ac. Bull. M. C. Z., V., No. 9, p. 190, Pls. I. II., 1878.
Yucatan Bank, off Havana, Lesser Antilles. 76-450 fathoms.
For list of Stations, see Bull. M. C. Z., VIII., No. 2, p. 80, 1880.

Pl, XM:

This magnificent species is by far the most striking Sea-urchin I have
seen. I shall always remember the particular haul, when, on the edge of
the Yucatan Bank, the dredge came up containing half a dozen of these
huge brilliant lemon-colored Echini.

The test is covered by small primary tubercles of uniform size, quite regu-
larly arranged on the plates of the test, both on the ambulacral and inter--
ambulacral areas. The tubercles on the actinal side are similarly arranged,
with the exception of the vicinity of the ambitus, where they are” more
closely crowded together. The primary tubercles are surrounded by a deeply
sunken scrobicular area, much as in Echinolampas and Rhynchopygus. The
miliary tubercles are uniformly scattered between the primaries, and are
separated by irregular transparent glassy ridges and elongated pits, much
as we find them on the actinal side of Rhynchopygus; but near the ambitus
on the actinal side, where the primary tubercles are most closely crowded,
they are separated by closely packed secondary tubercles. The actinal
bourrelets are very prominent; the floscelle is large, broad, well defined, ex-
tending nearly one third the distance from the actinostome to the ambitus.
There are small, elongate, short-stemmed, slender pyramidal pedicellariz
scattered irregularly over the actinal surface; they are much less numerous
on the sides of the test. The primary spines are short, slender, cylindrical,
rapidly tapering at the extremity; the miliary and secondary spines are
similar to the primary ones, but smaller. The apical system is compact,
the genital plates all coalesce, the centre of the apex is occupied by the
madreporie body, which is developed into a prominent knob, on the sides
of which the ocular plates rise. There are four large genital openings ;
the odd posterior genital is wanting. The ambulacral zones are all iden-
tical in structure, two rows made up of distant pores extending two thirds

CONOLAMPAS SIGSBEI. 49

of the distance from the apex to the ambitus, forming the rudimentary
petaloid ambulacra. At the extremity of these petals, the pores suddenly
come close together, the poriferous zones becoming extremely narrow, and
continue thus narrowed to the ambitus, and over to the actinal side, until
they meet the floscelles. The anal system is covered by an outer row of
three large plates and one smaller one, with a few smaller plates closing the
outer edge of the anal system.

It was with considerable hesitation that I referred this species, when first
deseribed, to the genus Conoclypus. While it undoubtedly agreed with it in
having a central apical system, a high conical test, and the five ambulacra
of the abactinal side equally developed, yet the arrangement of the pores
(Pl. XVIL. Fig. 7) and the development of the phyllodes and of the bourrelets
(Pl. XVII. Fig. 5), the transversely elliptical anal system (Pl. XVII. Fig. 6),
and the structure of the apical system (Pl. XVII. Fig. 3), seemed to ally
it more closely to Echinolampas. From the latter genus it differed, how-
ever, in the arrangement of the petaloid ambulacra, which do not form open
petals as in the species of Echinolampas thus far known, but merely straight
poriferous zones, not furrowed (Pl. XVII Fig. 2), extending close to the
ambitus. This feature alone would perhaps seem insufficient as a generic
distinction, for we find in L. depressa of Gray that the ambulacral petals are
modified somewhat from the characteristic Echinolampas type (2. oviformis),
and besides not having closed petals, the poriferous zones of the different
ambulacra are all of unequal length, somewhat as in EF. Alexandri De Lor.
(see Pl. XVI. Fig. 1), one of the characters by which Prof. F. J. Bell*
attempted to separate the genus Paleolampas from Echinolampas. De
Loriol+ is of opinion that the characters on which Mr. Bell attempts to
establish the genus Palzolampas are insufficient, yet we may find it con-
venient from the great variation we find in the petaloid areas of Echino-
lampas to adopt Paleeolampas as a subgeneric type. +

Zittel was the first to show, in his Handbuch der Paleontologie (I. 515),
that some species of the genus Conoclypus possessed teeth. This led De
Loriol to make an examination of this genus, and he found that it really
contained two generic types, one with phyllodes, which was edentate, and
another in which there is no trace of phyllodes, but an enormous develop-
ment of the bourrelets, which is provided with teeth. For the first type

* Proc. Zodl. Soc. London, 1880, p. 43. $ See page 46.
+ Mém. de la Soc. de Phys. et d’Hist. Nat. de Genéve, 1880, XX VII. 88.

59 CONOLAMPAS SIGSBEI.

De Loriol has proposed the name of Phylloclypeus.* These discoveries
led me to make a renewed examination of Conoclypus Sigshe. On opening
a specimen I found that it was edentate, as had been suggested by De
Loriol from the presence of the well-developed phyllodes (Pl. XVII. Fig. 5)
characteristic of Echinolampas and of the edentate Conoclypus type he
called Phylloclypeus. On comparing the structure of the actinostome in
Conoelypus Sigshei, as seen from the interior, with that of Echinolampas, J
found very striking differences. As is well known, im Lehinolampas Hellet
(Pl. XV. Fig. 9, Rev. Echini) the test immediately round the actinal open-
ing rises slightly, in a conical shape, above the general level of the actinal
floor. This is also the case in £. depressa, but in both cases the edges of
this conical elevation form a smooth ring round the actinostome, the cone
being in fact merely the turning up of the outer edges of the last plates
immediately adjoining the actinostome. In Conoclypus Sigsbet, on the con-
trary, the structure of the ring of plates round the actinostome is quite
similar to that described by Zittel and De Loriol m Conoclypus with
teeth ; the processes which support the jaws, although wanting (Pl. XVII.
Fig. 4), are still indicated by slight angular knobs, and we also find the
deep pits described by these authors in the interambulacral areas at the
base of this elevated ring.

This structural feature is one of the most interesting found among Echini,
as it seems to show us the direct passage, as it were, between the edentate
Echini and those provided with teeth. We have no full description as yet
of the jaws of Conoclypus, but enough is known to show us how closely
allied they are to those of the Clypeastroids. In Conoclypus they are evi-
dently held in place by vertical processes, very similar to those which thus
far have been considered as characteristic of the Clypeastroids. With the
diminution in size of the jaws in these types we must expect to find genera
in which the supporting processes alone are left, and we thay look for them
in the forms allied to the genus Phylloclypeus of De Loriol. The next stage
will be the practical disappearance of these processes, their former presence
being indicated by mere knobs, as in Conoelypus Sigsbet, until we get the
typical modern Echinolampas, in which the plates forming the actinal ring
rise only as a low cone above the general level of the actinal floor, and all
traces of these processes and of the interambulacral actinal pits have dis-
appeared. It may be convenient for the present to call this modern rep-

* Mém. de la Soe. de Phys. et d’Hist. Nat. de Genéve, 1880, XX VII. 79.

CONOLAMPAS SIGSBEI. 51

resentative of the Conoclypei, with its central apex and characteristic ambu-
lacra, by the name Conolampas, until we know more of the structure of the
interior of the actinostome of the Cretaceous genus Phylloclypeus of De
Loriol, as well as of the species of Echinolampas with high test, to which
this species of Conolampas may perhaps be more closely related than now
appears. Cotteau has figured such a species of Echinolampas (£. semiordis,
Guppy) from the Eocene of St. Barthélemy, and he likewise calls attention
to its resemblance to several species of Conoclypus.

As I have already stated in the Preliminary Report of the Blake Echini
(Bull. M. C. Z., V., No. 9, p. 191), I deseribed in the Revision of the Echini,
and figured on Pl. XVI. of that work, several stages of the young of Cono-
lampas ( Conoelypus Sigshei A. Ag.) as the young of Echinolampas. I had not
at that time dredged Conolampas, and was thus misled, by the examination
I had made of only a few young stages either of Echinolampas or of Cono-
lampas, to consider them all as belonging to the same genus.

Additional young specimens of Echinolampas and of Conolampas having
been obtained in the Caribbean by the Blake, Iam now able to rectify my
error, and, by referring to the figures given on Plate XVI. of the Revision,
to indicate those which belong to Echinolampas, and those which represent
young stages of Conolampas.

It will be seen that in corresponding stages of growth of these two genera
we find in one case, in young specimens of Echinolampas, already the first
trace of the peculiar petaloid development of the ambulacra characteristic
of this species (Pl. XVI. Figs. 6, 7, Rev. Echini); while in the corresponding
young stages of Conolampas (Pl. XVI. Figs. 4, 11, 12, Rev. Echini) the
ambulacra have the characteristic structure of the genus. To recapitulate,
Figs. 6, 7, 17. 18, 19, 21, of Plate XVI. of the Revision, belong to Kchino-
lampas, while Figs. 1-5 and 8-16 of the same plate belong to the young
stages of Conolampas.

The Pygaster or Echinoconus * stage, if I may so call it, of both Echino-
lampas and Conolampas, appears to be a most characteristic stage of these
genera, and it is possible that the recent species mentioned by Lovén as
Pygaster relictus, may after all only be a young stage either of Echinolampas
or of Conolampas. This is very probable judging from the size of Lovén’s
specimen, 3 mm. in diameter, and from its origin, the Virgin Islands.

* See the excellent figures of a fine series of Echinoconus given by Cotteau in Bull. Soc. des Scien. Hist.
et Nat. de ’Yonne, (2,) IV., 1881, Pl. I.

52 URECHINUS NARESIANUS.

Pourtalesia miranda A. Ac.

Off Havana, Grenada. 242-576 fathoms.

The fragments of other Pourtalesix, dredged principally oif the Barbados,
to which I referred in Bull. M. C. Z., VIII., No. 2, p. 80, 1880, belong prob-
ably to the genera Cystechinus and Spatagocystis. The fragments are too
imperfect for determination, and have no value beyond the fact that they
indicate the presence of other species of the group in the West Indies.

Urechinus naresianus A. Ac.
Lesser Antilles, Lat. 41° 24’ 45” N., Long. 65° 35’ 30” W. 422-1242 fathoms.

Pl. XXVL. Figs. 1-8.

The greater part of the specimens collected by the Blake measured
about 50 mm. in length, but varied greatly in height. They agree quite
closely with what I have designated as the normal stage in the Report of the
Challenger Echini. (See Chall. Ech., Pl. XXX*. Figs. 7-9, p. 146.) The
specimens examined all show but three genital openings. The structure of
the subanal fasciole shows that in this genus it assumes all the stages of de-
velopment intermediate between a well-defined subanal plastron, such as is
figured on Plate XXX*. of the Challenger Echini Report, and a stage in
which this fasciole is indicated merely by irregular accumulations of mili-
ary tubercles. So that the genus Urechinus is the representative of the
oldest Spatangoids with a disconnected apical system, large ambulacral and
interambulacral plates with simple linear ambulacral pores, in which the
subanal fasciole (the only one existing) is still in process of formation ; this
type of Spatangoid leading us little by little to Spatangoid genera in which
the ambulacra become more or less petaloid, as in Homolampas, Paleopneus-
tes, and the like, till we get the modern type of Spatangus proper, with.
well-defined petaloid ambulacra, and a highly developed subanal fasciole,
the lateral fasciole existing in some of these genera, Paleopneustes, Lino-
pneustes, Calymne, Maretia, ete., in a rudimentary form, as accumulations of
miliary tubercles along the ambitus. On the other hand, a slender peripeta-
lous fasciole is in some genera, Paleopneustes, Homolampas, Rhinobrissus,
ete., developed as a slender thread, or as a more or less well-defined fasciole
extending across the termination of the more or less rudimentary petals.

We find the lateral fasciole developed from the peripetalous fasciole in

PALAOTROPUS JOSEPHIN.®. 53

such genera as Hemiaster, Rhinobrissus, Linthia, Schizaster, etc., on the one
side; and on the other, in such genera as Paleopneustes, Maretia, Lino-
pneustes, Homolampas, ete., we find the more or less rudimentary lateral
fasciole plainly developed from the anal or branches of the subanal fas-
ciole, or independently.

This corresponds fairly well with the two series we find among the fossil
genera, in one of which the lateral fasciole is the appendage of the peri-
petalous fasciole, and in the other of the fasciole of the anal system, or has
arisen entirely independently as an ambital lateral fasciole, if I may so

call it.

Palzeotropus Josephine Lovuy.

Off Havana, Lesser Antilles. 82-242 fathoms. a _f *
For list of Stations, see Bull. M. C. Z, VIIL, No. 2, p. 81, 1880. | Ae

Pl. XXIII. Figs. 5-14.

A small specimen 10 mm. long did not differ from that figured by Lovén
(Pl. XU. Figs. 108-113, Eludes sur les Echinoidées). Older specimens ineas-
uring 23 mm. in length, figured on Plate XXIIL, are comparatively less
globular and more flattened, but otherwise do not vary greatly in appearance
from the younger specimens. In the Preliminary Report * on this collection
I had referred a few larger Spatangoids to this species; but on denuding
them from spines I find that they have nothing in common with Palotro-
pus, and they are described in this Report as belonging to a new genus
(Palzeobrissus) intermediate between Platybrissus and Argopatagus.

The test of this species is comparatively bare (Pl. XXIII. Figs. 5-11), car-
rying but few primary spines; these are generally straight, with a smooth
shaft, only a few of the very largest spines being slightly serrated. The
miliaries and secondaries are more numerous, generally club-shaped at the
extremity, often curved, and many of them with serrated shafts. The mili-
ary tubercles of the anal fasciole carry comparatively long, slender, slightly
club-shaped spines.

The coloring of small specimens is of a greenish violet, the whole test
being irregularly covered with distant dark violet pigment-spots. With in-
creasing size these spots become less numerous, concentrating mainly about

the base of the primary spines.

* Bull. M.C. Z., VIIL, No. 2, p. 81.

d4 PALAOTROPUS JOSEPHINE.

There is little difference in the arrangement of the ambulacral plates in
older or younger specimens. The two large genital openings, already present
in the youngest specimens known, have greatly increased in size, and the
madreporic openings are better developed in larger specimens (Pl. XXIII.
Fig. 12). The mode of formation of what has been called a compact abacti-
nal system is admirably shown in the structure of the apex of Paleeotropus,
in which the exterior sutures of all the plates adjoining the interambulacral
areas are most distinct, while the interior junction of the genital plates has
become completely obliterated (Pl. XXIII. Fig. 12), they being still sepa-
rated by the odd imperforate genital plate which is intercalated between
them, and of which the posterior and lateral sutures are still well marked,
while the interior anterior sutures are no longer visible. In Paleobrissus
the sutures of all the plates of the apex can be distinctly detected.

In the youngest stages, as well as the larger, we find near the actino-
stome in each ambulacral area one or two unusually elongate spheeridia.
They have a comparatively long reticulated stem, and it is interesting to
note that in some of the larger specimens we find near the ambitus on the
actinal side peculiar miliary spines which I am inclined to consider as modi-
fied spheridia. These peculiar spines have the shaft of a miliary, but the
tip is swollen out to a clear sphere resembling in all respects the head of
spheeridia, of which the base of attachment is usually merely rudimentary, as
described by Lovén; in addition we have such types as the spheeridia typical
of the actinal side of the genus Paleotropus. This would seem to show
that the spheeridia, like the pedicellaria, the spines of the fascioles, and
perhaps other appendages of the test of Echini, are only modified forms of
spines.

Danielssen and Koren* have figured peculiar spines of Hymenaster,
which also throw considerable light on the nature of the spheridia. They
are clusters of reticulations at the base of a central shaft, much like the
reticulations figured by Lovén as characteristic of the base of sphezeridia.
These spines are surrounded by a bag-like pouch representing undoubtedly
for Starfishes the bag-like appendages of certain spines of Asthenosoma and
Aspidodiadema, which in their turn seem to have close affinities with the
peculiar gland of certain Kchinid pedicellariz described by Sladen and
others, as I have already noticed in the description of some remarkable

spines occurring on the test of Aspidodiadema.

* Plate II. Figs. 2, 3, Nyt. Mag. for Naturvid., XXVIII.

PALZOTROPUS THOMSONI. 55

In the larger specimens of Paleotropus Josephine there is a slight tendency
to the formation of very rudimentary bourrelets. The larger outer plates
of the actinal system carry a few minute miliary tubercles and spines. (PI.
XXIIL Fig. 14.) On the abactinal surface the ambulacral suckers are
slender, surmounted by a small indistinct sucker, the tentacles increase in
size towards the ambitus, and near the actinostome there are four or five
large fimbriated tentacles in each ambulacral area.

The pedicellariz are most varied, representing types characteristic of the
Clypeastroids as well as the Spatangoids. On the actinal side there are in
the ambulacra, near the outer edges, minute slender, long-stemmed, two-
jointed pedicellarize with small pear-shaped trifid heads. At the ambitus,
interspersed among the preceding, are short-stemmed, large-headed, stout
pedicellariz resembling the Clypeastroid types. In the bare interambulacral
spaces there are a few large-headed, short-stemmed, trifid pedicellariz, some
with short prongs, others with long crossing prongs. Scattered irregularly
over the abactinal surface are few distant triangular-headed trifid pedicel-
lari, with long, slender stems, and short, flexible head-joints. The heads
of these last pedicellarix are of two very different sizes, but otherwise they
do not differ.

* Paleotropus Thomsoni A. Ac.

Paleotropus Thomsoni A. Ac. Bull. M. C. Z., VIII, No. 2, p. 80, 1880.
Lat. 32° 43’ 25” N., Long. 77° 20’ 30” W. 233 fathoms.

At Station 321 a single broken specimen of this species was collected,
which differs most strikingly from all the other specimens of Palzotropus.
It is closely covered by uniform tubercles on the abactinal side. It has a
proportionally greater number of coronal plates, and a high test, with a
keeled posterior interambulacral median line. Apex more posterior than in
P. Josephine.

The color of the test is yellowish white when alive. The large P. Josephine
are of a dirty greenish red color, and when young more pinkish. This
species is also remarkable for its broad, bare posterior lateral ambulacra on
the abactinal side, and for its prominent keeled, very elongate actinal plas-
tron, and its longitudinally elongate anal fasciole, still very prominent at a
time when in P. Josephine the posterior extremity has become flattened, and
the fasciole quite indistinct.

ob PALAZOBRISSUS HILGARDI.

*Paleobrissus Hilgardi A. Ac.

Station No. 300. 82 fathoms, Barbados.
Station No. 295. 185 fathoms, Barbados. t

Pl XXIV. Figs. 6-16.

At the time of writing the Prelimimary Report on the Echini of the
Blake cruise in the Caribbean, the specimens of this species were not
distinguished in the first examination from Paleotropus Josephine, to which
they have, when covered with spines, a general resemblance both in shape
and coloring (Pl. XXIV. Figs. 6-8). Palaeobrissus is one of the most inter-
esting generic types collected by the Blake. From the structure of its
ambulacra it is closely allied to both Platybrissus, Nacopatagus, and Argo-
patagus. The ambulacra are not petaloid, as in the former genus. The
pores of the lateral ambulacra are arranged in straight, double, diverging
rows (PI.-XXIV. Fig. 10). The pairs of minute pores of the abactinal region
increase rapidly in size towards the extremity of the rudimentary petals,
the last four pairs being large and well separated, the outer pore of each
pair slightly larger than the inner one ; the lateral ambulacral petals extend
nearly to the ambitus (Pl. XXIV. Figs. 11, 12). The odd anterior ambula-
crum is not as prominently developed as the lateral ambulacra, the pores
remaining all small (Pl. XXIV. Fig. 10). There are four genital pores (PI.
XXIV. Fig. 15), the anterior pair the smallest, separated from each other
by the well-marked madreporic pores, which conceal the sutures between
the anterior genital plates. The posterior genital plates are comparatively
large, adjacent, becoming intercalated with the median posterior interambu-
lacral plates. The anterior part of these genital plates is perforated by the
large elliptical posterior genital pores. The structure of the apical system
of this genus shows how the abactinal interambulacral plates are derived
from the terminal plates of a compact apical system; these are not neces-
sarily the genital plates, but may be intercalated plates formed from the
subdivision of any of the abactinal interambulacral plates at the apical junc-
tion of the posterior lateral interambulacra with the odd interambulacrum.

The upper part of the test (Pl. XXIV. Fig. 10) is covered by small pri-
mary tubercles of uniform size, somewhat distant, quite regularly arranged
on the plates, increasing in number towards the ambitus. The intertuber-
cular space is filled by distant miliaries, also quite uniformly scattered over

HOMOLAMPAS FRAGILIS. 57

the test. The primary spines are small, slender, and straight. The miliary
spines, similar in structure to the primaries, are not more than a third
to a quarter their length. When covered with spines, the coloring is of a
dark greenish violet ; denuded, the test is of a pinkish gray.

On the actinal side (Pl. XXIV. Fig. 9) the primary tubercles are more
closely packed in the interambulacral areas and on the actinal plastron,
but the anterior ambulacral plates towards the actinostome, as well as the
posterior lateral ambulacral areas on each side of the actinal plastron, are
left bare. The posterior lip of the actinostome is but slightly developed
(Pl. XXIV. Figs. 9,15); there is a tendency to the formation of rudimentary
bourrelets from the crowding of small secondary tubercles on the interambu-
lacral edges of the actinostome (Pl. XXIV. Fig. 13). The anterior part of
the actinal opening is covered by eight large polygonal plates of irregular
outline ; the remaining space on the posterior part of the actinostome along
the actinal lip (Pl. XXIV. Fig. 15) is covered by smaller irregulaily arranged
plates.. The actinal plates all carry minute secondary tubercles.

The anal system (Pl. XXIV. Fig. 14) is circular, surrounded by two or
three concentric rows of irregularly arranged plates.

The large actinal tentacles are fimbriated; towards the ambitus and _ be-
yond it, until they reach the extremity of the petals, they become simple
with a slight sucker. The tentacles of the petaloid region are broad, flat-
tened, with an indistinct sucking disk,

The ambulacra carry, as in Palxotropus, short-stemmed, stout-headed, and
short-stemmed, large-headed trifid pedicellarix. Scattered irregularly over
the test are long-stemmed, large, slender, open-headed trifid pedicellariz.

Homolampas fragilis A. Ac.

Homolampas fragilis A. Ac. Bull. M. C. Z., V., No. 9, p. 191, 1878.
Florida Bank, Lesser Antilles. 734-1920 fathoms.

Fragments of a large specimen of Homolampas, very probably the adult of
LT. fragilis A. Ag., of which young specimens were dredged by Mr. Pourtalés
(see Revision of the Echini, Pl. XVII. Figs. 13-21). These fragments show
H. fragilis to be closely allied to the large species of the same genus (JZ.
fulva, A. Ag.) described and figured in the Report on the Echinoidea of the
Challenger (Pl. XXIV.). The Caribbean species differs from it, however,
by the closer tuberculation of the miliaries, the larger number of primary

98 PALEOPNEUSTES CRISTATUS.

tubercles in the interambulacral areas near the abactinal system, and the
coarser tuberculation of the odd anterior groove above the ambitus; also in
having a larger number of primary plates. No part of the anal system or

of the actinal system was found among the fragments.

Paleopneustes cristatus A. Ac.

Off Havana, S. side of Cuba, Lesser Antilles. 56-450 fathoms.
Most common to the leeward of the West India Islands, between 90 and 150 fathoms.
For list of Stations, see Bull. M. C. Z., VIII., No. 2, p. 81, 1880.

PE XX.

A number of specimens of this species have been collected by the Blake,
which are interesting as throwing additional light on the variability of the
so-called lateral fasciole of this genus, and in showing the changes due to
growth. Thus far only large specimens of this genus had been described,
both from the Hassler and the Challenger expeditions. I have added to
the figures of two of the principal stages of growth given on Plate XXI.
Figs. 6-14, details of the actinostome (Fig. 5), of the apical system (Fig. 3),
of the termination of the lateral petaloid ambulacra (Fig. 1), of the edge of
the test near the ambitus from the abactinal side (Fig. 2), taken from a large
specimen of this species measuring nearly 150 mm. in length and 80 mm. in
height, as these details could not be very clearly seen in the photographic
illustrations of this species in the Memoir on the Echini of the Hassler
Expedition (PI. IV. Figs. 1-3, Ill. Cat. M. C. Z., No. 8).

A small specimen measuring 45 mm. in length (Pl. XXI. Fig. 7) differed
from the specimen figured in the Hassler Echini merely in size, and in
having an indistinct lateral fasciole extending obliquely from the abactinal
end of the anal system to the edge of the test, reaching the ambitus at the
anterior lateral ambulacra, and extending faintly across the anterior part
of the test along the ambitus. See Plate XXI. Fig. 7, and Fig. 8, which
shows a small part of this fasciole close to the ambitus across the anterior
ambulacral area. This can hardly be termed a lateral fasciole; it reminds
us of a similar fasciole in Calymne, and it is difficult to decide in these cases
whether this single fasciole should be called peripetalous as it passes across
the posterior extremity of the test above the anal system, or a lateral
fasciole occurring isolated from a peripetalous one; or whether it represents
a rudimentary stage of the peripetalous fasciole, not crossing the ambulacra

PALEOPNEUSTES CRISTATUS. 59

at the extremity of the petaloid ambulacra or the petals themselves, as in
one of the species of Rhinobrissus, but crossing them below the petals at
an indefinite place of the test; so that we might have an interior fasciole, as
in Lovenia; a true peripetalous fasciole, as in Hemiaster; a transpetaloid
fasciole, as in Gualteria and Rhinobrissus ; or a marginal fasciole, as in some
stages of growth of Paleopneustes and in Linopneustes; all representing
different stages of development or modification of a petaloid fasciole. This
simple series becomes complicated with the possible simultaneous existence
of an internal and peripetalous fasciole or of a true peripetalous fasciole
with a more or less marginal fasciole, forming in that case a lateral fasciole
proper. In a specimen of this species measuring about 85 mm. in length,
the marginal fasciole is traced only with difficulty near the ambitus across
the anterior lateral ambulacra (Pl. XXI. Fig. 8), and it seems to disappear
completely in somewhat older specimens. But in ali the stages of growth
that part of the ambitus and’ of the test adjoming the course of the mar-
ginal fasciole is thickly studded with miliaries and small secondary tubercles
(Pl. XXI. Figs. 2, 6, 8).

In Linopneustes this marginal fasciole has assumed practically all the
characters of a peripetalous fasciole crossing the posterior lateral ambulacra
just at the end of the petals, while it still crosses the anterior ambulacra a
short distance below the end of the petals. Neither in Pa/eopneustes eristatus
nor in P. hystrix do we find any trace of a rudimentary subanal fasciole, either
as an indistinct band or a part of a band, or even as accumulations of miliary
tubercles ; and it is interesting to note that in species so closely allied as
P. cristatus and Linopneustes Murray there should be so striking a distin-
guishing feature as the presence or absence of a subanal fasciole, while
in other genera of Spatangoids, Paleotropus, Urechinus, and Schizaster, in
specimens of the same species, such as Urechinus naresianus, we should have a
complete series passing from a well-defined subanal fasciole to a mere accu-
mulation of miliary tubercles.

The smallest specimen collected, measuring about 16 mm. in length, is
somewhat more flattened than the older stages, and shows as yet no trace of
petals, the ambulacral plates and pores extending uniformly from the apex
to the ambitus and actinostome without the specialization of any portion.
(Pl. XXI. Figs. 9-11.) In this stage I could see no indication of a marginal
fasciole. The apex was compact, but there was no trace as yet of any
genital openings, and the madreporic body was very faintly indicated (PI.

60 PALEOPNEUSTES HYSTRIX.

XXI. Fig. 12). In the apical system of the large specimen figured here
(Pl. XXI. Fig. 3), the madreporic body covers nearly the whole of the space
between the genital plates; the two left anterior plates, as well as the right
posterior plate, are adjacent and perforated.

In the specimen measuring 45 mm. in length the apical system, as well as
the anal system and the actinostome, had already assumed all the charac-
teristic features of the larger and older specimens.

In the smallest specimen the actinostome is quite pentagonal (Pl. XXI.
Fig. 13), and the posterior actinal lip only slightly indicated. The plates
covering both the actinal opening and the anal system do not differ greatly
in number in the older and very young specimens (compare Pl. XXI. Figs.
13, 14, and Figs. 4,5). The few comparatively large and distant primary
tubercles of the interambulacral plates (Pl. XXI. Figs. 9, 10) give to the
young Paleopneustes a very different facies from its older stages.

* Paleopneustes hystrix A. Ac.

Paleopneustes hystrix A. Ac. Bull. M.C. Z., VIII., No. 2, p. 82, 1880.
Saba Bank, Guadeloupe. 21-208 fathoms.

Pl. XVII, Pl. XIX. Fig. 2 (lower figure).

Seen in profile (Pl. XIX. Fig. 2) this species is flatter and has a more
conical outline than P. crisfalus. I know of no Spatangoid which has such
large, stout primary spines as those which cover the interambulacral areas
of the abactinal side of the test, though in Lovenia they are longer, and in
Linopneustes they are as long but not as stout. They resemble more in ap-
pearance the spines of a large specimen of Echinus acutus than of a Spatan-
goid. They are straight, comparatively stout, some of the primary spines
measuring in length nearly a fourth of the test. These large spines are
carried on distant tubercles, not more than three in each of the larger inter-
ambulacral plates of the abactinal surface near the ambitus, and only two
towards the apical system. Four or five small secondary tubercles irregu-
larly placed on the plates, with distant minute miliary tubercles, compose
the whole tuberculation of the interambulacral part of the test (Pl. XVIII.
Fig. 2). The ambulacra carry no primary tubercles, only distant milia-
ries and a few small secondary tubercles in the median interpetaloid space.
Below the petals the ambulacral plates carry one large primary tubercle

PALEOPNEUSTES HYSTRIX. 61

surrounded by four or five secondaries with the same scattering of distant
miliaries.

The secondary spines of the abactinal surface are small, slender, sharp,
short, slightly curved, about 5 mm. in length ; the delicate miliary spines are
about half that length. Toward the ambitus the tuberculation becomes
closer, and on the actimal side (Pl. XVIII. Fig. 5) the primary tubercles
are somewhat smaller and arranged in three irregular horizontal rows, quite
closely packed on the interambulacral plates, with only a few scattered sec-
ondary tubercles and less numerous miliaries than on the abactinal surface.
This tuberculation extends also over the ambulacral plates on the actinal
side, so that in this species there is nothing of the broad bare ambulacral
avenues, extending from the ambitus to the actinostome found in other
species of this and allied genera. On the actinal side the spines are pro-
portionally smaller, more slender, shorter, slightly curved and spathiform,
as in other Spatangoids.

The phyllodes (Pl. XVIIE. Figs. 5, 6, 7) are remarkably prominent in this
species, and the actinostome is larger in proportion to the diameter of the
test than in P. erisfatus. In a specimen measuring 115 mm. in length, the
actinal opening measures 25 mm., while in a specimen of P. er7sfafus measur-
ing 144 mm. in length the actinostome measures only 27 mm. The other
principal differences of P. hystrix from P. cristalus are seen in the abactinal
system and the ambulacral petals. There are four genital openings; but
in some specimens the left anterior genital is not as fully developed as
the others. It is therefore probable that in some cases we may find only
three genital pores, as in P. cristatus. The ambulacral plates are compar-
atively higher and wider than in P. cvisfalus; in addition, the pairs of
pores are placed nearer the outer edges of the ambulacral plates than in
P. cristatus, where they are situated nearly in the centre of the plates.
This causes the semi-petaloid part of the ambulacra to diverge more rapidly
than in the other species of the genus, the pairs of pores at the lower
extremity of the petals being nearly twice as distant as in P. crisfalus.
There is considerable variation in the size of the pores of the petaloid
ambulacra; as a general rule, on the outer rows, the pores are comma-
shaped and much larger than the comparatively small pores of the inner
rows, but in other specimens this difference is not so striking. When alive
the color of the test varies greatly ; it is in some specimens of a rich light
chocolate color, from which stand out in striking contrast the long yel-

62 LINOPNEUSTES LONGISPINUS.

lowish gray primary spines of the abactinal surface ; in others, the test and
spines are of a greenish purple, the most common coloring of the test being

a light Indian-red with primary spines of the same tint.

* Linopneustes longispinus A. Ac.

Linopneustes longispinus, A. Ac. Bull. M. C. Z., VIII., No. 2, p. 82, 1880.
Eupatagus longispinus A. Ac. Bull. M.C. Z., V., No. 9, p. 191, 1878.
Off Havana, Lesser Antilles. 38-250 fathoms.

Pi. XIX. Fig. 1 (upper fig.); Pl. XX.

This species was first noticed as Lupatagus longispinus, from a number of
somewhat imperfect fragments, showing this large Spatangoid to be related
to Eupatagus, Platybrissus, and Paleopneustes. A number of specimens since
collected off the West India Islands show that it is closely allied to Lino-
pueustes Murray?.

The test of this species is depressed, apex slightly anterior. It holds in
the genus Linopneustes the same relation to L. Murrayi which Paleopneustes
hystrix holds to P. eristalus. Both P. eristatus and L. Murrayi are covered on
the abactinal side with a close tuberculation, carrying comparatively small,
stout, slender primary spines; while P. dystriv and L. longispinus both are
characterized by the few and comparatively large primary tubercles seated
on the plates of the interambulacral areas of the abactinal surface. In
all the specimens I have examined, varying from 65 to 110 mm. in length,
the marginal fasciole (Pl. XEX. Fig. 1) is most prominent, forming a nar-
row band carrying minute dark-colored miliary spines all round the abac-
tinal ambital edge (PI. XX. Fig. 8) of the test, passing at the posterior
extremity close to the upper part of the anal system. In this respect the
course of the fasciole of this species of the genus Linopneustes differs strik-
ingly from the tertiary Pericosmus, in which the marginal fasciole follows
the same course close to the ambitus, but its posterior extremity passes
under the anal system. Desor has called attention to the variability of
this fasciole, which in the fossil species of the genus Pericosmus appears to
be often as ill defined and as variable as in the recent species of Lino-
pneustes. j

The subanal fasciole of Linopneustes longispinus (Pl. XX. Fig. 8) is trans-
versely elliptical, irregularly hexagonal with rounded corners, and narrower
than the corresponding fasciole of Z. Murrayi. The anal system is also

LINOPNEUSTES LONGISPINUS. 63

comparatively smaller, and covered by smaller plates than in that species,
and is transversely elliptical. The apical system in both the species of
Linopneustes is more compact than in Paleopneustes.

The odd anterior ambulacrum of Z. dongispinus is more sunken at the ambi-

tus than in the Japanese species. The lateral ambulacra are more petaloid
than in any other species of either Linopneustes or Paleopneustes thus far
known; in some specimens they end at the extremity much as they do in
Eupatagus. (Pl. XX. Fig. 1.) The petaloid pores of the two rows are of
nearly the same size, placed close together on the outer edge of the ambula-
cral plates. The petals extend somewhat more than half-way from the
apex to the ambitus. Tle secondary tubercles are small, of uniform size,
and the whole surface of the test is uniformly covered by minute miliaries.
The primary spines of the abactinal surface are long, slender, curved, (PI.
XIX. Fig. 1, Pl. XX. Fig. 1,) some of them measuring nearly a quarter of
the test in length. The thin slender and straight secondary spines are not
more than 3 or 4 mm. long; the thin hair-like miliary spines are nearly as
long, and are generally curved.

On the actinal side of the test the primary tuberculation is close in the
posterior lateral interambulacral areas on one or two plates near the ambitus,
but towards the actinostome the primary tubercles increase in size (Pl. XX.
Fig. 5), and at the same time become less numerous. The tuberculation of
the actinal plastron is smallest along the median line, the tubercles increas-
ing in size towards the outer lateral edge adjoining the broad bare posterior
interambulacral areas. The spines of the actinal surface are shorter and
more slender than those of the abactinal surface ; they are curved, and those
adjoining the bare posterior ambulacral zones are more spathiform than the
spines on the rest of the actinal surface. The actinostome of this species
is comparatively smaller (Pl. XX. Fig. 6) than that of Z. Murray, meas-
uring only 10 mm. in longitudinal diameter in a large specimen of 105
mm., while in one of LZ. Murrayi of 85 mm. the actinostome measures
nearly 15 mm.

When alive, the test is pinkish or flesh-colored, the large primary
spines of the abactinal surface having a yellowish tint with a whitish
silvery lustre.

64 MACROPNEUSTES SPATANGOIDES.

*Macropneustes spatangoides A. Ac.

Spatangus purpureus A. Aa. (non Luske nec auct.). Bull. M. C. Z., VIII., No. 2, p. 83, 1880.
Lesser Antilles. 82-373 fathoms.

Pi. XX VAI.

The fragments of the Spatangoid which I referred in the Preliminary Re-
port to Spatangus purpureus, | find on closer examination to belong to the
genus Macropneustes. Although no complete living specimen was dredged,
yet a sufficient number of dead broken tests were collected to enable me to
restore this species satisfactorily, with the exception of the part near the
anal system. In general appearance and outline, as seen from above, this
species resembles Spatangus purpureus; but it can at once be distinguished
by the high anterior part of the test, which in the abactinal part of the odd
ambulacrum rises above the apical system.

The anterior ambulacrum is deeply sunken at the ambitus, in a groove
similar to that of Linopneustes longispinus. In old specimens the abactinal
part of the ambulacral petals are disconnected, much as in Echinocardium,
within the internal fasciole. On the actinal surface the tuberculation is quite
uniform in specimens of very different sizes. The larger primary tubercles
are found on the anterior part of the test, and in the posterior interambula-
eral area they diminish gradually in size towards the posterior extremity,
and become more closely crowded. The tubercles of the actinal plastron
are smaller and of uniform size. On the abactinal surface the primary
tubercles are limited to the interambulacral areas within the peripetalous
fasciole, except along the line of the middle of the posterior interambu-
lacral area, along which the V-shaped angular lines of primary and _sec-
ondary tubercles extend, gradually diminishing in size towards the anal
system. Within the peripetalous fasciole the arrangement of the primaries
varies greatly. In some specimens there are not more than nine or ten
large tubercles in the apical part of the interambulacral areas; in others
the primary tubercles form V-shaped figures in each plate, the smaller tuber-
cles on the lower side of the plates. In other specimens, again, the large
tubercles form merely irregular horizontal lines. The rest of the surface
of the test within the petaloid area to the actinal side is closely packed with
small miliary tubercles, often concentrated more or less on the lower part
of the coronal plates so as to form V-shaped areas. The petaloid ambulacra

MACROPNEUSTES SPATANGOIDES. 65

are closed at the extremity, the anterior pair is considerably larger than
the posterior pair. The outer rows of pores are the largest in both lateral
petals. The pairs of pores are sunken. The odd anterior ambulacrum con-
sists of lines of single pores, one for each ambulacral plate. Apical system
compact, with four genital openings and small madreporic body.

The most interesting structural feature of this genus is the composition of
the peripetalous fasciole, and the light which this throws on the possible
origin of the fascioles as a whole. As is well known, in Macropneustes the
peripetalous fasciole forms a clear, simple narrow band around the extremity
of the petals. This we find to be the case also in some specimens of this spe-
cies of Macropneustes. In others, the anterior part of the fasciole beyond the
extremity of the anterior petals becomes indistinct or disappears. In still
other specimens, the posterior part of the fasciole across the odd interambu-
lacral area widens, forming elongated V-shaped areas: sometimes there are
two or three such areas. In other cases a similar structure extends across
the lateral ambulacra. In other cases, again, only a few such disconnected
V-shaped areas take the place of the fasciole; as these become less numer-
ous and more indistinct, the fasciole disappears completely. These V-shaped
areas form as it were secondary posterior and lateral branches of the peripet-
alous fascioles, similar to the anterior bands observed by Troschel in Tripylus.
Across the anterior ambulacrum there are sometimes no less than six or
seven such secondary fascioles, some of the upper branches uniting agam
with the main fasciole, others extending parallel to the ambitus across the
ambulacra into the lateral ambulacra, where the extremities die out in the
crowded miliary tubercles covering that part of the test. In some of
the specimens the miliaries of the lateral ambulacral and interambulacral
areas below the peripetalous fascioles show a tendency to be crowded towards
the lower edges of the plates, thus forming indistinct V-shaped areas resem-
bling somewhat the V-shaped areas of the secondary fascioles, but made up of
course of larger tubercles. This suggests the question whether the bare
sutural bands characteristic of some of the genera of Cidaride, Arbaciade,
Temnopleuridx, and other Echinoids, are not the first trace of fascioles. So
that we may consider the concentration of the miliary and secondary miliary
tubercles on the edges of certain plates, or in the centre, so as to form bare
sutural lines or bands along certain parts of the test, either in the ambula-
cral or interambulacral areas, as the first indication of the formation of fasci-
oles, or as rudimentary or disconnected fascioles.

66 HEMIASTER MENTZI.

This concentration of the secondary miliaries seems in some other genera
to take place in old specimens. ‘This is particularly well shown in large
specimens of Metalia pectoralis (see Pl. XXI. Fig. 5, Revision of the Echini) ;
in small specimens measuring not more than half the size of the one figured,
this structure is very indefinite. In some large specimens of Spatangus
purpureus a slight tendency to a similar concentration of the secondary
miliaries could also be detected.

The anal system is transversely elliptical, measuring 16 mm. in a specimen
of 95 mm. in length. In the same specimen, the subanal fasciole is broad,
enclosing a somewhat heart-shaped area vertically elongate, measuring about

17 mm. along its greatest diameter.

*Hemiaster Mentzi A. Ac.

Hemiaster Mentzi A. Ac. Bull. M.C. Z., VIII., No. 2, p. 83, 1880.

Lesser Antilles. 170-626 fathoms.

This small species is characterized by the globular outline of the test, and
by the narrow, comparatively elongate space included within the peripetalous
fasciole. It has a larger number of buccal plates than ZZ. gibbosus. The
tuberculation is coarser and more distant than in that species, more as it
is in HZ. zonatus and H. expergitus. As m the latter species, the posterior
extremity of the test is vertically truncated nearly flush with the rest of
the test, the anal system but slightly sunken, witha mere trace of an anal
groove. The test forms over the abactinal part of the anal system a very
rudimentary hood. ‘This species is also remarkable for the great develop-
ment of the suckers of the odd anterior ambulacrum. In a specimen
measuring 17 mm. in length the suckers still retain the prominence they
have in very young Spatangoids. (See the figure of young Brissopsis in
Rev. Echini, Pl. XLX. Figs. 1, 2.) This embryonic character is not the only
one this species retains; its globular form, the position of the peripetalous
fasciole near the abactinal system, the short comparatively simple peta-
loid lateral ambulacra, are all features it has in common with the young
of other Spatangoid genera. In the only other species of the genus of
which the changes due to growth have been traced (Henuaster cavernosus,
Challenger Echini, Pl. XX*. Figs. 7-14), the odd anterior ambulacrum does
not assume the great prominence it has in the young of this species. In a
small specimen of ZZ Menizi, measuring 7 mm. in length, the peripetalous

RHINOBRISSUS MICRASTEROIDES. 67

fasciole is broad, elliptical, and the greater part of the space it encloses is
filled by the huge suckers of the odd anterior ambulacrum. The close
resemblance of this stage of Hemiaster to an Aérope is very marked, and
the permanence of the unusual development of the tentacles of this odd
anterior ambulacrum up to the adult stage is an important link in tracing
the aflinities of such widely separated genera as Hemiaster, Brissopsis, Agas-
sizia, Aérope, Aceste, and Schizaster.

The structure of the larger interambulacral spines in the young stages
(7 mm. long. diameter) well shows the manner in which the fantastic shape
of some of the Spatangoid spines is produced. The outer sheath of calcareous
rods becomes solidified as thin lamella, forming in one case in the primary
interambulacral spines of the anterior part of the test on the abactinal side,
above the ambitus, a spearlike head to the shaft of the radioles; this may
have a more or less lobed edge, or if the radiole is curved it forms a some-
what shallow spoon-like extremity with spiny processes; in the shorter
radioles of the actinal plastron the lamelle all develop into this spoon-shaped
extremity, which may be perfectly symmetrical, or else developed une-
qually on one side, according to the position of the radioles on the actinal
plastron.

In the earlier stages the fascioles are already covered by the same kind
of pavement which we find in the adult, made up of short-stemmed, club-
shaped spines closely packed together. There were in some of the larger
specimens a few large, short-stemmed, globular pedicellarie, irregularly scat-
tered over the abactinal surface of the test.

Rhinobrissus micrasteroides A. Ac.

Rhinobrissus micrasteroides A. Ac. Bull. M. C. Z., V., No. 9, p. 192, 1878.
Off Havana, 175 fathoms. é SK
Station 321, Lat. 32° 43/ 25” N., Long. 77° 20' 20” W. 233 fathoms. Jame — ke

Pl XAT Wigs, f=) PL XRVE Fig. p

It is with considerable hesitation that this species is retained in the
genus Rhinobrissus, the only specimen obtained by the Blake being a
somewhat damaged young stage. From what is known of the modifica-
tion of the Spatangoids due to growth, there are no characters in this
single specimen which are not probably merely modifications due to age.
The ambulacra are all flush with the test, and remind us of the earliest

68 RHINOBRISSUS MICRASTEROIDES.

Spatangoids in the geological series. The thin, narrow, ill-defined peripeta-
lous fasciole crosses the petals without affecting their structure, as it does in
all the recent Spatangoids. The ambulacra are not petaloid, the ambulacral
plates are large, the pairs of pores are distant, and extend nearly to the
ambitus. Homolampas fulva A. Ag., among the Challenger Echini, has
similar embryonic lateral ambulacra, with large plates, and flush with the
test, Gualteria alone among the fossils representing a similar stage of this
structure in Rhinobrissus.

The indefinite peripetalous fasciole existing with a well defined broad
and prominent subanal fasciole indicates that in Spatangoids the fascioles
either may have become developed from the peripetalous fasciole, first
making its appearance in such genera as Hemiaster, in which, however, the
subanal, lateral, and anal fascioles are wanting; or may have developed
mainly from the subanal fasciole in such genera as Micraster ; Rhinobris-
sus in the stage here figured (Pl. XXIII. Figs. 3, 4) representing a Micraster
stage to which has been added an indistinct peripetalous fasciole, while
Periaster would represent the Hemiaster stage with rudimentary subanal
and anal fascioles. Another species of the genus collected by the Challenger
represents a later stage of development, with sunken lateral ambulacra, a
peripetalous, an anal, and a subanal fasciole indicating affinities with the
more specialized recent, Schizasteride.

In a fragment of the upper part of the test, which undoubtedly belonged
to a specimen of this species measuring at least 50 mm. in length, the lat-
eral ambulacra were as yet scarcely sunken, and almost flush with the test,
the anterior ambulacrum, however, towards the ambitus, being indented
and sunken, much as in the genus Homolampas. ‘This fragment is interest-
ing, as it shows that the peripetalous fasciole is not continuous, disappearing
in the anterior interambulacral areas before it reaches the odd ambulacrum.
The subanal fasciole, judging from a fragment of that part of the test, must
have been remarkably prominent.

It is possible that a young Spatangoid which I figured in the Revision of
the Echini (Pl. XIV. Fig. 11) may turn out to be the young of this species
of Rhinobrissus. It has, like this species, a peripetalous fasciole crossing the
petals without modifying their structure ; and large ambulacral plates. It
differs from it, however, in having a continuous lateral fasciole passing under
the anal system, as in Agassizia.

This species of Rhinobrissus (/?. mécrasteroides) will probably form the basis

BRISSOPSIS LYRIFERA. 69

of a subgenus of Rhinobrissus, which will hold to it very much the same
relation which Periaster holds to the true Schizaster. It will represent the
embryonic stage of Rhinobrissus and recall to us the earliest true Spatangoid
genera of the Chalk still having ambulacra nearly flush with the test, with a

well-developed subanal and a rudimentary peripetalous fasciole.

Brissopsis lyrifera Acass.

Lesser Antilles, off Havana. Lat. 28° 51’ 30” N., Long. 89° 1’ 30” W. Off the mouth of the
Mississippi. Lat. 41° 29’ 45” N., Long. 65° 47’ 10” W. 118-1394 fathoms,
For list of Stations, see Bull. M. C. Z., VIII, No. 2, p. 83, 1880.

Pl. XXVI. Figs. 7-18.

Lrissopsis lyrifera appears to be one of the most widely distributed species
of the Atlantic fauna, and is also found in the Caribbean and in the Gulf of
Mexico,

I have already, in the Revision of the KEchini (p. 354), spoken of the
great variation I had observed in the course of the petaloid ambulacra of
this species, as well as of the variations found in the subanal fasciole. An
extensive series of specimens of this species has now been brought together
by the dredging of the Blake. These throw additional light on the changes
we may expect to find among Spatangoids of this group in one and the
same species. I had already observed considerable difference in the outline
of the test. Specimens dredged off the mouth of the Mississippi were
generally quite globular, and presented the extreme form in that direc-
tion, while the specimens collected along the east coast of the United
States as far north as George’s Bank, and in the Eastern Caribbean and
the Straits of Florida, although varying considerably in outline, yet pre-
sented no very marked differences except such as we have seen were due
to growth, and agreed on the whole quite well with the specimens of
Brissopsis known from other parts of the North and South Atlantic. Be-
tween Jamaica and San Domingo there were dredged three specimens of
Brissopsis representing the extreme elongated form, with an anteriorly
bevelled flat surface, at the abactinal extremity of which is situated the anal
system. These specimens were further characterized by an exceedingly well
defined subanal fasciole, with an indistinct anal fasciole extending to the
posterior part of the peripetalous fasciole. As mentioned in the Revision of
the Kchini, the subanal fasciole is quite variable; in many cases the anal

70 BRISSOPSIS LYRIFERA.

branch is clear and well marked, in others it becomes gradually reduced and
indistinct, or finally disappears entirely. The subanal fasciole also appears
in the American specimens to be subject to great variations. In the globular
specimens from off the mouth of the Mississippi, the subanal fasciole was in
some cases well defined, in others somewhat indistinct; in others again only
very indistinct and disconnected parts could be traced; and finally in others
it had disappeared entirely, as is the case in the genus Toxobrissus, which
differs from Brissopsis only in having no subanal fasciole and confluent lat-
eral ambulacra, characters which are here distinctly shown to occur in this
species of Brissopsis in specimens found in different localities. The speci-
mens with globular test have retained that embryonic feature alone, while
the petals and fascioles have developed in what we might call the normal
manner. The excessively elongate and flattened forms found off Jamaica
retain of the embryological characters the confluent ambulacra and the
position of the anal system on the anteriorly sloped surface, a feature re-
calling the time when the anal system was distinctly placed on the abactinal
surface of the test, and not on the vertically truncated posterior extremity as
is usually the case.

In Brissopsis, as in Macropneustes and other Spatangoids, the centrali-
zation of the tubercles on certain parts of the plates shows how closely this
is connected, on the one hand, with the formation of V-shaped fascioles in the
interambulacral and ambulacral areas, as in Macropneustes. In the inter-
ambulacral areas the absence of tubercles leaves bare the median and hori-
zontal sutural lines, the median spaces and adjoining angular connections
being broader than the horizontal lines. The anterior ambulacra are bare
from the extremity of the petals, while in the posterior ambulacra the an-
terior row of ambulacral plates alone is bare, the posterior row being closely
crowded with miliaries. The flat surface enclosed within the branch of the
anal fasciole is bare in the central region, somewhat coarsely tuberculated
at first towards the exterior; gradually the tuberculation becomes smaller,
until it passes into the fine miliaries which form the anal branch of the
fasciole, extending from the subanal to the peripetalous fasciole along the

central line of the posterior row of ambulacral plates.

AGASSIZIA EXCENTRICA. all

Agassizia excentrica A. Ac.

Florida, Cuba, Lesser Antilles. 86-391 fathoms.
For list of Stations, see Bull. M. C. Z., V., No. 9, p. 193, 1878; VIII., No. 2, p. 88, 1880.

Bi XOXGV.

When alive the test is covered with spines of a delicate pinkish gray color,
darkest at the base. The ambulacral areas are covered with slender, long-
stemmed, small-headed pedicellariz, articulated at the base, while in the
interambulacral system the miliaries carry slender, straight, or slightly
curved club-shaped spines, scarcely stouter than the stems of the pedicel-
lariz. The fascioles are still more thickly crowded with similar minute
pedicellariz and club-shaped miliary spines, but somewhat shorter, and
closely dotted with large pigment spots.

The actinostome of the genus is marked for the irregular arrangement of
the buccal plates. The anal plates are few in number, often less than eight,
comparatively large, and form in the young stages a regular anal pyramid,
as characteristic as that figured by Gray, Lovén, and myself in Palzeostoma.

A few of the tentacles of the odd anterior ambulacrum, near the apical
system, are fimbriated like those surrounding the buccal system; those
immediately following towards the ambitus are simple, with a slight sucking
disk like the tentacles of the anterior rows of pores of the lateral petaloid
ambulacra. Within the petaloid area the tentacles of the posterior rows are
broader, compressed, irregularly lobed at the extremity; the tentacles beyond
become, as in the anterior rows, simple towards the ambitus, and remain
so till they join the large fimbriated tentacles surrounding the buccal
system. The presence of large fimbriated tentacles near the apical system
in the odd ambulacral petal shows that Agassizia is itself an embryonic
genus. Other features of the same character are the general globular form,
and the rudimentary structure of the lateral anterior ambulacra; the an-
terior rows of pores of the posterior lateral ambulacra appear only after
the posterior rows are well developed.

In a specimen measuring 3 mm. in length,’the first ambulacral tentacles to
appear are those surrounding the actinostome, which were nine in number
and already fimbriated. In the denuded test of a specimen of about the
same size, no trace of the subdivision of the test into coronal plates could
be detected ; it consisted entirely of a close network of fine granulation.

i AGASSIZIA EXCENTRICA.

The position of the ambulacral and interambulacral areas was indicated by
the presence of rows, more or less irregular, of rudimentary, primary, and
secondary tubercles; those of the actinal plastron and of the interambulacral
areas being generally more closely defined than those of the ambulacral
areas. In this stage the actinostome is pentagonal, with rounded corners,
the posterior lip being but slightly mdicated.

In a specimen measuring 6 mm. in longitudinal diameter, the posterior
lip is quite pronounced, and the actinostome has become transversely ellip-
tical, but the number of buccal tentacles has as yet not increased. The
granulation covering the test of the youngest stage examined (3 mm. long)
is arranged in short parallel lines forming irregular lozenges, perhaps like
those figured by Lovén in the actinal system of several other Echini; * but
the boundaries of these figures, if they have any regularity, could not be
traced. This stage of the test of Agassizia, covered as it is by a fine gran-
ulation such as we find characteristic of the granulation of the fascioles in
some of the Spatangoid genera, naturalky suggests the idea that the fascioles
are merely bands formed by the remnants of the embryonic granulation of
the test on which tubercles proper have not yet developed. This rudimen-
tary granulation, arranged in more or less regular lozenge-shaped figures, is
a very general structural feature of the coronal plates of many Echini, in
which we can trace it readily in the younger stages. See especially Salenia
and young Kchinide and Cidaridz, as well as other Spatangoids. It is also
found in the structure of the plates of the calyx of many Crinoids, and
of some plates among the Starfishes, and we are justified in regarding this
granulation as the typical structural ornamentation of Echinoderms, which
has become specialized in recent times to form among the Spatangoids the
so-called fascioles. This would explain the presence of detached bands of
fascioles parallel to the principal ones, such as we find in Maretia, Homo-
lampas, Paleopneustes, Macropneustes, and Brissopsis.

If this view of the nature of fascioles is correct, we should be justified
in considering the papille of the Cidaridxe arranged regularly round the
primary spines of the interambulacral areas, as well as the ambulacral pa-
pille, as modified fascioles not occupying special limited areas. The same
would be true of the papilla of the Salenie. <A similar explanation would
hold good for the down-like spines covering the greater part of the test of
Aspidodiadema, and the long hair-like spines of Echinothrix, Centrostepha-

* Lovén, Etudes sur les Bchinoidées, Pls. XIX., XXI.

AGASSIZIA EXCENTRICA. 73

nus, Astropyga, and other Diadematide and Echinothurix ; in the last, there
is, as I have shown, even what we might consider in some cases a regular
marginal fasciole, as in Phormosoma. The miliary granulation of the Cly-
peastroids generally, and the comparatively small radioles they carry, may
according to this view be considered as embryonic features which have
become greatly specialized, the whole test retaiming the granular tubercula-
tion characteristic of the earlier Crinoids, with but slight modifications in the
fasciolar radioles covering the whole test, if I may so call them, while they
become, strictly speaking, minute primary or secondary radioles.

Although in the young stages of such Spatangoids as Hemiaster, Bris-
sopsis, Schizaster, and the like, the fascioles make their appearance very
early, yet in this youngest stage of Agassizia there is at a corresponding
period no well-defined fasciole band, and it is only in a somewhat more
advanced stage (4 mm. long. diam.) that we get a clearly defined fasciole.
This seems to affect the character of the spines found above and below it,
and we have in the stage just mentioned a well-defined lateral marginal
fasciole close to the ambitus. This fasciole is in reality only an extension of
the subanal fasciole, such as we find a remnant of in Argopatagus. The
peripetalous fasciole is also developed, and its anterior extremity comes down
close to the ambitus, as it does in Paleopneustes.

In the youngest Agassizia (3 mm, long. diam.) there are three or four
single pores forming the rudimentary petals of the lateral ambulacra. The
apical system is represented in this stage merely by the large madreporic
body which covers the whole apex. The surface of the test in these younger
stages, more especially in the ambulacral areas, is covered by numerous
small-headed, short-stemmed pedicellarie and by minute straight miliary
spines, often club-shaped.

In a specimen measuring 6 mm. in longitudinal diameter, the odd ante-
rior ambulacrum was not yet developed at all; the lateral ambulacra con-
sisted of six and seven pores, the anterior ambulacra being composed of
single rows of pores, the posterior ambulacra of double rows; the anterior
rows of the posterior ambulacra were made up of three small pairs of pores

with a couple of single pores near the apex of the ambulacrum.

Meoma ventricosa Lut.

Florida Bank, and off Havana, 37-127 fathoms.

Gi a} ‘werlin (P ln at 1 ay < cet) it

(CUE dS aoe a era ae PU) Fae Near

74 SCHIZASTER FRAGILIS.

Schizaster fragilis Acass.
Quite a common species near the 100 fathom line, off the New England coast. 71-362 fathoms.
For a list of Stations, see Bull. M. C. Z., VIIL, No. 2, p. 84, 1880.

Pl. XXVIII. Figs. 8-14.

There is considerable variation in the distinctness of the lateral fasciole as
it passes under the anal system. In some cases it stops suddenly near the
level of the anal system; in others it can be faintly traced as an indistinct,
irregular anal fasciole ; in others the anal fasciole is most clearly marked.
These differences do not depend on size, but specimens from one locality are
usually similarly affected. Small specimens measuring 6 mm. in longitu-
dinal diameter are but slightly elliptical when seen from above, the anterior
ambulacrum scarcely indented, and the lateral ambulacra still flush with the
test. The actinal side is slightly convex, the outline seen in profile is
hemispherical, the apex being nearly central; the circular anal system,
flush with the test, is placed high on the posterior extremity of the test.
Both the peripetalous and lateral fascioles are well marked as narrow bands
of miliaries, indicating in a very rough way the future indentations of the
course of the fascioles. In this stage the posterior ambulacra consist only of
two pairs of pores, and are scarcely one quarter the length of the anterior
lateral ambulacra. There is no trace as yet of any genital openings. The
actinal opening is circular, without a posterior lip, and the posterior edge
of the actinostome is placed nearer to the central part of the actinal side
than to the anterior edge of the test.

In specimens measuring 10 mm. in length, the posterior lateral ambulacra
are still flush with the test, with five pairs of pores; the anterior ambulacra
are slightly sunken. The odd ambulacrum is more sunken than in the
younger stage described. The madreporic body, which in the preceding
stage was only pierced by a single opening, is now marked by five or six
small openings. There is as yet no sign of any genital openings. The
posterior extremity of the test is more vertically truncated; the anal system
is more elliptical, and placed at the upper angle of the posterior level of the
test. The fascioles are somewhat broader than in the younger stage; they
vary in width, the angles of the ambulacra assuming more clearly already
the general course they finally take in larger specimens. The actinal open-
ing is now placed well towards the anterior extremity. The outline of the

SCHIZASTER FRAGILIS. 45

test from above is still elliptical, with the exception of the anterior re-entering
angle of the odd ambulacrum and of the posterior extremity of the test.
The apex is now posterior to the abactinal system, the anterior extremity
sloping gradually toward the ambitus, while the posterior extremity of the
test extends nearly horizontally to the junction of the vertically truncated
posterior extremity.

In specimens measuring 23 mm. in length the outline of the test when
seen from above shows traces of the angular projections which characterize
the full-grown specimens. ‘The test is slightly pointed posteriorly. The
odd ambulacrum is deeply sunken nearly to the apical system, while in the
preceding stages the odd ambulacral groove extended only a short distance
from the ambitus to the apex. The lateral ambulacra are now all sunken,
the posterior ambulacra somewhat less than the anterior pair; these have
now eleven pairs of pores. There are three large genital openings, the two
left anterior ones and the right posterior one. The fascioles have nearly
assumed the course and shape they take in the adult. The posterior ex-
tremity is bevelled towards the actinal extremity, so that over the anal
system the test projects slightly beyond the general outline. The actinal
system is now quite flat, the actinostome has a well-developed posterior lip,
of which a trace only can be found in specimens measuring about 10 mm.
in length. The tuberculation and the corresponding spines have now as-
sumed the general characteristics of the tuberculation at different parts
of the test; while in younger stages the tubercles were few in number,
comparatively large, and irregularly arranged over the sides and upper
surface of the test. The actinal plastron is the first to appear, and in the
youngest specimens examined the tuberculation of that area as well as
the spines had already become specialized to a certain extent.

In specimens measuring 34 mm. in length, the test, as seen from above
and in profile, has assumed the outline of adult specimens; and we find
already in specimens of this size as much variation in the closeness of the
tuberculation, the depth of ambulacral furrows, the course and shape of
the fascioles, the outline of the test as seen from different points of view,
and the specialization of the spines of different parts of the test, as we do
in the larger specimens. -

|
Oo

SCHIZASTER ORBIGNYANUS.

*Schizaster orbignyanus A. Ac.

Schizaster orbignyanus A. Ac. Bull. M.C.Z., VIII., No. 2, p. 84, 1880.

Lesser Antilles. 92-1507 fathoms.
Pie XX VILL, Pigs 1-7

This species extends as far north as the New England coast, specimens
having been dredged by the United States Fish Commission off Martha’s
Vineyard in 100 and 130 fathoms. They differ very considerably from the
specimens dredged by the Blake in the Eastern Caribbean. The northern
specimens, while retaining the characteristic outline of those from the Carib-
bean, yet differ from them in having a much broader peripetalous fasciole,
more like that of S. canulferus ; the northern and southern specimens, again,
agree in the great width of the actinal plastron at the posterior extremity,
and the small size of the anal system as compared with that of 8. cana-
liferus, and are covered by a closer tuberculation also, a character which
readily distinguishes the specimens of the two species thus far compared.
The test from the lower side of the anal system to the edge of the actinal
plastron is more bevelled than in S. canalferus, In the few specimens ot
S. orbignyanus | have had occasion to examine, the lateral and anal fascioles
vary greatly in distinctness. In the Caribbean specimens the lateral fasciole
extends continuously along the sides of the test to the level of the side of
the anal system, and there forms a sharp, well-defined triangular anal fasciole.
Jn the northern specimens the lateral fasciole is often indistinct or disappears
entirely, only the anal fasciole remaining. It is interesting to note that, in
the specimens of S. fragilis dredged off our eastern coast, the. anal fasciole
disappears first, leaving only a part of the lateral fasciole extending from the
peripetalous fasciole towards the anal system. The peripetalous fascioles
are of a dark violet color, forming a strong contrast to the greenish yellow
spines with silvery lustre which cover the upper part of the test. The lateral
and anal fascioles can scarcely be distinguished by their color from the spines
of the actinal side and those towards the ambitus, which with the exception
of the spatula-shaped spines of the actinal plastron are of a darker color than
those of the abactinal side of the test, and within the peripetalous fasciole.

Whether the differences here noted between S. cunaliferus and S. orbigny-
anus are merely local or more important, comparisons of more extensive series
of these species alone can determine.

=i
=H

SCHIZASTER LIMICOLA.

*Schizaster (Periaster) limicola A. Ac.
Schizaster (Periaster) limicola Acass, Bull. M. C. Z., V., No. 9, p. 193, Pl. IIL, 1878.
Pl. XXVI Figs. 5,6.

This species belongs to the generic group of Schizaster separated as Peri-
aster by D’Orbigny from the genuine Schizaster. The test is quite globular,
when seen from above the outline is somewhat angular, the posterior ex-
tremity is vertically truncated, with a slight keel between the posterior
petals near the apex; the anterior extremity has a shallow ambulacral
groove, and is vertically truncated from the edge of the peripetalous fasciole.
The lateral anterior petals are nearly twice as long as the posterior one, as
well as broader. The petals are all about equally sunken. The peripetalous
fasciole has the shape and position of that of Schizaster proper; the anal
fasciole is narrow, extending only a short distance on the sides of the test.

The test is thickly covered with primary tubercles of a uniform size, car-
rying short, slightly curved spines on the sides; the tubercles are somewhat
more crowded within the fasciole and on the abactinal region of the odd pos-
terior interambulacral area. The coronal plates between the fasciole and the
anal system are comparatively bare, having only few tubercles on the outer
edges. On the actinal side the primary tubercles are larger, more distant,
except on the actinal plastron, where they are closely crowded, and carry
longer, larger, and curved primary spines. The actinal lip is very sharp and
prominent; the actinal membrane carries one large exterior row of plates
round the anterior edge of the actinostome, and smaller irregular plates over
the rest of the actinal surface. The anal system is comparatively small for
so large a species. The separation of this group of Schizaster as a generic
type seems very doubtful. It is based solely upon the more globular outline
of the test, and the discontinuity of the latero-anal fasciole. It may be con-
venient to form a subgeneric group with these characters; but when we
attempt to draw the line between such forms as S. ventricosus and S. japoucus,
it becomes most difficult, if not impossible, to draw the line of demarkation
between the generic and subgeneric types.

We find the same difficulty in attempting to define the numerous generic
subdivisions indicated by Troschel for the genus Tripylus and its allied forms,
which pass insensibly to Faorina and the like, while in Schizaster the devia-
tions are in the direction of modifications passing into Periaster, Epiaster,

78 SCHIZASTER LIMICOLA.

Hemiaster, and the like. The structure of the odd anterior ambulacrum of
this species has all the characteristics of the odd ambulacrum of such species
of Schizaster proper as S. canaliferus, S. fragilis, and S. Philippi, while it has
the outline of the test of Hemiaster and the fascioles of Periaster. There are
but two genital openings. When brought up in the dredge, this species was
of a dirty yellowish-brown color. This species has an extensive geographical
range, having been collected by the Challenger in the Arafura Sea.

The Schizasterids which have been united under the generic name of Peri-
aster are interesting as representing a truly embryonic stage of Schizaster
proper. As is well known from the study of the young of several species of
Schizaster in the earliest stages of growth, they have a globular test, the
ambulacral grooves are either indistinct, or only slightly developed, or totally
absent. The peripetalous fasciole is broad, but slightly indented ; in fact, all
the characteristic features of the genus are those which we find in the young
stages of such species of Schizaster as S. orbignyanus, S. fragilis, and S. japon-
wus. If we were to magnify a young S. fragilis measuring about 10 mm. in
diameter about six times, we should have a fair representative of the genus
Periaster, provided we took into account the great variation of the lateral
fasciole, which is more or less indistinct as it passes towards and under the
anal system to form the anal fasciole in such species as S. fragilis and SN.
Moseleyi. The odd anterior ambulacrum is, like all the other ambulacra, but
slightly sunken, and indicated by a broad re-entering angle at the ambitus,
neither of the lateral pairs of ambulacra being as deeply sunken as in
Schizaster proper, the posterior pair being, as in most of the Schizasteride,
shorter than the anterior pair. The relative proportions of the lateral
ambulacra recall to a certain extent the structure of the ambulacra of the
older Spatangoids of the Chalk, such as Hemiaster proper. In large speci-
mens of Periaster limicola measuring 68 mm, in length, there are two pos-
terior genital openings, as in Hemiaster, the ocular plates are large, and
the madreporic body is elongate, extending longitudinally over the greater
part of the apical system.

ess MAS arr 1 -¥ (

ORIGIN OF THE WEST INDIAN (CARIBBEAN) ECHINID FAUNA.

Tue resemblance of the Fauna of the Gulf of Mexico and of the Caribbean
to that of the Pacific has been noticed by former writers, even at a time
when the materials available for comparison included but little beyond the
littoral Fauna. Since the results of the deep-sea dredgings have become
known, the extent of this resemblance has become quite striking. In fact,
the deep-sea Fauna of the Caribbean and of the Gulf of Mexico is far more
closely allied to that of the Pacific than to that of the Atlantic. Before the
Cretaceous period, the Gulf of Mexico and the Caribbean were undoubtedly
in freer communication with the Pacific than with the Atlantic Ocean ; so
that, while probably before that time the Fauna of these seas contained a
number of Atlantic types, yet the characteristic genera were common to the
Pacific. Many of the genera have remained unchanged to the present day
since the absolute separation of the Atlantic and of the Pacifie by the Isth-
mus of Panama and the Mexican Plateau, while there have been added to
the West Indian Fauna a number of Atlantic types, which, as long as the
Gulf of Mexico and the Caribbean were practically a part of the Pacific,
probably did not find conditions as suitable to their development as those
which now exist, and which have existed since their separation from the time
they became merely extensions of the equatorial Atlantic district.

This explanation gives us an apparently good reason for the mixed char-
acter of the Fauna of the West Indian seas, showing us at the same time
that, however long a period of time may have elapsed since this separation
has taken place, it has not been sufficient to effect any very radical change
in the Echinid Fauna of the two sides of the Isthmus. The principal differ-
ences are due to the immigration of true Atlantic types into the West Indian
faunal region during the Tertiary and Post-tertiary period. But as the prin-
cipal physical conditions of the sea in the tropical regions of the two sides
of the Isthmus appear to be so nearly identical, we could not expect any
great differences to arise between the Panamic and West Indian Faune from

physical causes alone.

50 ORIGIN OF THE WESTINDIAN ECHINID FAUNA.

In order to show the former distribution of the genera of which the Echi-
nid Fauna of the West Indies is made up, we must trace as far as possible the
origin of these genera. We find at the outset a few old genera, like Cidaris,
Dorocidaris, Porocidaris, and Salenia, dating back to the Jurassic period, and
which already in the Tertiary had probably as extensive a geographical
distribution as at the present day. Dorocidaris and Porocidaris at the pres-
ent time are Atlantic and Indo-Pacific genera, while Salenia and Cidaris are
confined to the warmer belts of the same oceans.

Hemipedina, which dates back to the Jura, is found fossil in the Tertiary
of North America, and has thus far not been dredged outside of the Carib-
bean Fauna. Pygaster is also a Jurassic genus, but it is most probable that
the Pyyaster relictus is only the young of one of the West Indian Spatan-
goids with an ancient facies, as has been suggested by De Loriol. The
genera which date back to the Cretaceous period, either actually or by
closely allied genera, are Podocidaris, Asthenosoma, Phormosoma, Tem-
nechinus, Echinus, Echinocyamus, Conoclypus, Rhynchopygus, Pourtalesia,
Hemiaster, and Periaster.

Of these genera, Temnechinus, Echinus, Hemiaster, and Periaster already
had during the Tertiary as extensive a geographical range as to-day. At
the present time, Echinus extends over the Atlantic, the Indian, and the
Pacific Oceans; Temnechinus is a tropical Atlantic and Pacific genus ;
Hemiaster is characteristic of the Atlantic and of the North Pacific, Peri-
aster of the Kast American tropical Atlantic and tropical Pacific, and Rhyn-
chopygus appears limited to-day to the American faunal districts of the
same oceans, although it has been found in the Tertiaries of Australia and of
Europe. Nothing is known of the distribution during the Tertiary of the
Atlantic and Pacific genera Pourtalesia, Asthenosoma, and Phormosoma.
Podocidaris is a tropical Atlantic and Pacifie genus. Echinocyamus extends
in the North Atlantic to within the tropics.

The genera dating back to the earlier Tertiary period include by far the
greater number of the genera of the West Indian Fauna; they are Coelo-
pleurus, Strongylocentrotus, Trigonocidaris, Toxopneustes, Hipponoé, Clype-
aster, Echinanthus, Echinonéus, Neolampas, Echinolampas, Homolampas,
Paleopneustes, Linopneustes, Spatangus, Echinocardium, Rhinobrissus, Bris-
sopsis, Agassizia, Brissus, Metalia, Meoma, Macropneustes, Schizaster, and
Moira. Of these the genera extending in the equatorial belt of the Atlantic

and Indo-Pacific region are Trigonocidaris, Toxopneustes, Hipponoé, Clype-

ORIGIN OF THE WEST INDIAN ECHINID FAUNA. 81

aster, Echinanthus, Echinolampas, Homolampas, Paleopneustes, Linopneustes,
Rhinobrissus, Brissus, and Metalia. The genera having an Atlantic and
Pacific range are Strongylocentrotus, Spatangus, Echinocardium, Brissopsis,
and Schizaster. Leaving only with a more or less limited range Coelopleurus,
found in the Caribbean, Indian Ocean, and East Indian Archipelago, and
with nearly the same distribution in the Tertiary, having only disappeared
from the Eastern North Atlantic region where it once flourished. Echino-
néus, Coelopleurus, and Macropneustes have very much the same geographical
and geological range. Agassizia, Meoma, and Moira are probably strictly
tropical American genera, occurring both on the Pacific and Atlantic sides
of the continent; but they formerly had a much wider geographical distri-
bution, Agassizia having been found in the Tertiary of Egypt and Meoma
in Australia.

The genera dating back only to the later Tertiary period are Arbacia,
Echinometra, Mellita, and Encope. But little is known of their former geo-
graphical extension. Echinometra is a tropical Atlantic and Indo-Pacific
genus ; Arbacia is a tropical Atlantic and Pacific genus, most widely distrib-
utel on both sides of the American continent; while Mellita* and Encope
are eminently tropical American, occurring on both sides of the continent.

This leaves the genera Diadema, Aspidodiadema, Palzeotropus, Palzeobris-
sus, Urechinus, Cystechinus, and Aceste, which have as yet not been found
fossil. These genera, with the exception of Cystechinus, limited to the
Southern Atlantic and Pacific, and Paleeobrissus, which represents Platybrissus
in the Atlantic, have an extended geographical range in the tropical belt of
both the Atlantic and the Pacific Oceans. The nearest allies of Diadema and
of Aspidodiadema date back to the Cretaceous, and Palzeotropus, Palzeobrissus,
Urechinus, and Cystechinus are to-day the old-fashioned representatives of
the types of Spatangoids which characterized the Cretaceous seas.

This analysis shows that the Echinid Fauna of the West Indian seas of to-
day is made up (1.) of five genera which date back to the Jurassic period ;
(2.) of ten genera which go back to the Cretaceous period; (3.) of twenty-
four genera dating from the earlier Tertiary period ; (4.) of only four genera
characteristic of the later Tertiaries; (5.) of seven genera which we may
look upon as the representatives of the Ananchytide and Infulasteridee,
and of the Pseudodiadematide of the Cretaceous period. In all these old-

fashioned genera we find species having a cosmopolitan range.

* One species of Mellita is said to come from the Red Sea.

82 ORIGIN OF THE WEST INDIAN ECHINID FAUNA.

Of the so-called American genera, all containing most closely allied repre-
sentative species, Agassizia, Moira, Meoma, Macropneustes, Arbacia, Encope,
and Mellita, which probably flourished in the central American seas soon after
the closing of the Isthmus of Panama, the three Spatangoids date back to
the Cretaceous, the two Clypeastroids and two Echinidx to the later Ter-
tiary

We find the nearest allies of the Clypeastroids in the Tertiaries of
Western France and of Egypt; the above-named West Indian Spatangoids
and Clypeastroids, as well as Coelopleurus and Macropneustes, first disap-
peared from the Eastern Atlantic. The past history of the ten West In-
dian genera already found in the Cretaceous, and of the twenty-four genera
descending from the earlier Tertiary, gives us but little assistance in deter-
mining their probable mode of appearance in the Caribbean Fauna.

As far as we can now judge, the separation of the Caribbean and the Gulf
of Mexico from the Pacific was brought about by the formation of the Florida
and Yucatan Banks by their elevation above the level of the sea, in addition
to the raising of the Greater and Lesser Antilles, of the Plateau of Mexico,
and of the whole of Central America, ending in the complete closing of all
connection at the Isthmus of Panama. These elevations have been gradually
taking place from the close of the Cretaceous period to the most recent Post-
tertiary times, and to the successive changes they have brought about in the
physical conditions of the Gulf of Mexico and of the Caribbean Sea we
must ascribe in the main the existing state of the West Indian Echinid Fauna
as compared with the Echinid Fauna of other geographical districts.

It would be most interesting to be able to make a comparison of the deep-
sea Panamic Fauna with that of the Caribbean, and ascertain if in the con-
tinental and abyssal regions, at the depths beyond which the effects of light
and of heat are not prominent factors, we find as marked a difference in the
representative species as in those of the littoral Fauna.

The West Indian Echinid Fauna comprises more than a quarter of all the
known species of Echini, and if we take what we might call the tropical At-
lantie Fauna it includes a little over one third of all the known species. The
known species of the Indo-Pacific realm, which we might call the tropical
Indo-Pacific Fauna, are somewhat more numerous; so that we have more
than two thirds of all the known species of Echini belonging to this great
tropical oceanic belt, the northern and southern limits of which extend some-
what into the temperate regions. This leaves less than one third of the
known Echini as representatives of the other faunal districts. There are

ORIGIN OF THE WEST INDIAN ECHINID FAUNA. 83

only at present thirty-four genera characteristic of the Indo-Pacific not found
in the Atlantic, and only eight genera characteristic of the Atlantic not as
yet discovered in the Pacific,* while the Atlantic and Pacific have thirty-six
genera incommon. Of the genera they have in common, four date back to
the Jura, seven to the Cretaceous, sixteen to the Tertiary ; the others belong
to the Diadematidxe, which have their nearest allies in the Cretaceous, as
well as the five recent genera of Ananchytidz and Pourtalesiz.

Of the genera special to the Indo-Pacific, two date back to the Jura, as
many to the Cretaceous, twenty-one to the Tertiary ; there are left the genera
of Diadematidx, of Ananchytide, and of Pourtalesix, derived from the Cre-
taceous. The Echinometrade genera of the Pacific have no fossil repre-
sentatives. Of the special Atlantic genera, two are Jurassic, two Cretaceous,
one Tertiary ; the other has no fossil representative.

Soon after the end of the Cretaceous period the specialization of the great
Atlantic and Indo-Pacific marine realms began. Before that time the equa-
torial currents probably swept nearly uninterruptedly round the globe, and
maintained across the Indo-Pacific and Atlantic nearly the conditions exist-
ing in the Western Atlantic before the equatorial currents became deflected
by the West India Islands and the northern extremity of South America.
If the physical causes we now see at work have, as they became changed,
also modified the Fauna of the then existing equatorial belt district, we should
naturally expect to notice after a long period of time the changes they
brought about. We are probably justified in ascribing to the subdivision
of this great equatorial belt into an Indo-Pacific and an Atlantic district the
marked changes we can trace in the character of the Fauna as affecting the
genera which date back to the late Cretaceous, and which become still more
marked if we trace them in the genera dating back to the Tertiary period.

How far it is possible for us directly to follow the changes which have
taken place, and to trace the gradual passage of the older Fauna into the
characteristic West Indian Fauna of to-day, is another question. This in-
volves the necessity of tracing back from the Triassic and Jurassic periods
the genera which have appeared in succession, and how far this is prac-
ticable I have attempted to show on a former occasion.t I would also

* We should also bear in mind that, of the eight genera characteristic of the Atlantic alone, we find
closely allied representative genera in the Indo-Pacific realm.
+ Paleontological and Embryological Development, Address at the Boston Meeting for 1880 of the

American Association for the Advancement of Science.

84 ORIGIN OF THE WEST INDIAN ECHINID FAUNA.

refer for details to the List I have given in the Challenger Report * of known
species of Echini, where the bathymetrical, geographical, and geological
range is given as far as known at that time. To this List should be added
the deep-sea species collected by the “ Gazelle” and described by Studer,
and the necessary additions and modifications which are suggested in this
Report.

The following Table, containing a complete list of all the West Indian
species of Echini, extended so as to include the few species which thus far
have not yet been found in the West Indian district, has been prepared, for
the sake of comparing the West Indian species with the Panamic Echini,
and with the representative species of Echini found in the American de-
posits of the Post-Pliocene, Miocene, Eocene, Cretaceous, and Jurassic periods.
In the column of the principal localities, the present and past geographical
and geological extension of the genus is given, to allow a ready comparison
of the actual and former distribution of the present West Indian genera to
be made. The geographical range of each species is also given. When
several representative species have been described, they have all been

enumerated.

* Report on the Echinoidea : Report on the Scientific Results of the Voyage of H. M.S. Challenger,
Pt. IX., p. 208, 1881.

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ECHINI.

LIST OF THE WEST INDIAN

94

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TTY ULIpUy 489A (uvaqquie)

Seen from above.
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PAapAVT ES ot:

Dorocidaris Blakei A. Aa.

Natural size.
Natural size.

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1-15. Dorocidaris Blakei A. Ac.

Fig. 1. Portion of test seen in profile, facing the median interambulacral line, from a specimen 37 mm.
in diameter.

Fig. 2. Abactinal system of same.

Fig. 3, 4. Primary elongate radioles, similar to those of D. papillata.

Fig. 5. Primary radiole, somewhat flattened at extremity.

Fig. 6, 7. Primary radioles somewhat flattened and slightly fan-shaped at extremity.

Tig. 8-10, Primary radioles still more fan-shaped than those of the preceding figures.

Fig. 11-13. Small interambulacral radioles of the actinal side near actinostome.

Fig, 14, 15. Larger and stouter radioles of the actinal side near the ambitus.

16-27. Dorocidaris Bartletti A. Ac.

Fig. 16. Portion of test seen in profile, showing the ambulacral area and a few primary plates of the
interambulacral area, adjoining the apical system, from a specimen 50 mm. in diameter.

Fig. 17. Abactinal system of same.

Fig. 18-27. Different primary radioles taken trom a single specimen, showing the more or less serrated
structure between the two extremes of Fig. 23 and 27.

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Porocidaris Sharreri A. Aa.

Seen in profile. Natural size.

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1-2. Porocidaris Sharreri A. Aa.

Portion of test of specimen measuring nearly three inches in diameter. Seen in profile.

Abactinal system of same, both figures somewhat enlarged.

3-23. Salenia Pattersoni A. Aa.

Abactinal system of specimen 18 mm. in diameter.

Actinal system of same.

Portion of test of same, seen in profile, showing primary coronal plates above ambitus, facing
the median interambulacral line.

Portion of test of same above the ambitus, seen in profile facing the median ambulacral line.

Portion of ambulacral area of same, showing the Hemicidaris-like arrangement of the tubercles
at the base of the ambulacral area near the actinostome.

Primary spine of same. Natural size.

9-11. Ambulacral papillae of same, magnified.

7s
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19:
20.
21.

22.

g.12-14. Porocidaris-like interambulacral spines, near actinostome, magnified.
ADs

3.16.

Test of specimen 12 mm. in diameter, seen from the abactinal side.

Portion of test of same, below and at ambitus, seen in profile, facing the median ambulacral line
and showing the Hemicidaris-like ambulacral tubercles.

Actinal system of same.

Abactinal system of specimen 10 mm. in diameter.

Actinal system of same.

Portion of test of same, above ambitus, seen in profile, facing the median interambulacral line.

Portion of test of same, below and at ambitus, seen facing the median ambulacral line, to show
the Hemicidaris-like arrangement of the ambulacral tubercles.

Young Salenia 6.5 mm, in diameter, seen from the actinal side.

Fig. 23. Abactinal system of same.

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Salenia Pattersoni A. Ac.

Seen from above. Natural size.
Seen in profile. Natural size.

Seen from the actinal side.

Natural size.

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1-17. Salenia varispina A. Aa.

Young Salenia measuring 1.5 mm. (diameter of test), showing the fimbriated primary spines,
and the plates of the anal system.

Young Salenia 3 mm. in diameter, seen from the actinal side.

The same as Fig. 2, seen from the abactinal side.

Inner view of the abactinal system of a Salenia 8 mm. in diameter.

Part of actinal system, showing the imbricated plates in a young Salenia 7 mm. in diameter.

Part of the abactinal system of a young Salenia 2 mm. in diameter, showing the indistinct
lozenge-shaped arrangement of the primary striation of the test.

Actinal termination of one of the ambulacral areas, showing the position of the spheeridia and of
one of the pairs of buceal tentacles of a Salenia 8 mm. in diameter.

Interambulacral actinal area, showing also single sphwridia near the actinal extremity in each of
the ambulacral areas.

Magnified view of one of the pyriform spheeridia.

Fig. 9-11. Magnified views of interambulacral papille.

Fig. 12.
Fig. 13.
14.

Fig. 15.

16.
pills

Sessile papilla of the anal system.

Tube projecting beyond the genital opening.

Young forked primary spines of Fig. 1.

Stout-headed, short-stemmed trifid pedicellaria of the actinal surface.

One of the gills of a Salenia 8 mm. in diameter.

Sessile papilla of one of the genital plates of the abactinal system, covered with large pigment

spots, and still showing the primary striation.

18-23. Salenia Pattersoni A. AG.

.

Actinal part of ambulacral area of Salenia 14 mm. in diameter, showing the gills, the imbri-
cating plates, and one of the pairs of the buccal tentacles of the actinostome.

Tnterambulacral part of actinostome of another Salenia 14 mm. in diameter, showing the imbri-
cating plates of the actinostome and a pair of the large buccal tentacles, with comparatively
slender long-stemmed pedicellariz.

Part of actinostome of another Salenia of nearly the same size: the granulation of the actinal
plates is coarser.

The left posterior genital plate, showing the coarse granulation characteristic of the abactinal
system of this species, with minute globular spheridia in the notches of the plates, these
globular sphzeridia are similar to the pair of small, short-stemmed spheridia found at the
base of the ambulacral tentacles near the actinostome.

Part of coronal plates of test of Salenia 14 mm. in diameter.

Granulation of anal plate.

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Ccelopleurus floridanus A. Aa.

Fig. 1. Seen from above. Natural size.
Tig, 2, Same, seen from the actinal side, to show the bat-shaped spines of the actinal region.
Fig. 3. A smaller specimen, seen from above. Natural size.

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PLATE VIII.

Ccelopleurus floridanus A. Aa.

Fig. 1. Test of specimen measuring 28 mm., seen from the abactinal pole.
Fig. 2. Portion of test of the actinal surface of same, somewhat more magnified.
3. Portion of test of same, seen in profile, facing the median ambulacral line.
Fig. 4. Portion of test of same, seen in profile, facing the median interambulacral line.
5

. Portion of test, still more enlarged, to show the pits at the base of the median ambulacral line.

Fig. 6. Abactinal system of same specimen.

Fig. 7. Specimen 11 mm, in diameter, seen from the abactinal pole.

Fig. 8. Apical system of same.

Fig. 9. Portion of test of same, seen in profile, facing the median ambulacral line.

Fig. 10. Portion of test of same, seen in profile, facing the median interambulacral line.
Vig. 11. Specimen 9 mm. in diameter, seen from the abactinal pole.

Fig. 12. Apical system of same.

Fig. 13. Portion of test of same, seen in profile, facing the median ambulacral line.
Fig. 14. Portion of test of same, seen in profile, facing the median interambulacral line.
Fig. 15. Small specimen 6 mm. in diameter, seen from the abactinal pole.

Fig. 16. Portion of test of same, seen in profile, facing the median interambulacral line.
Fig. 17. Portion of test of sme, seen in profile, facing the median ambulacral line.
Fig. 18. Apical system of same.

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Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6
Fig. 7.
Fig. 8
Fig.

Fig. 10
Fig 11
Fig. 12
Fig. 13.
Fig. 14,
Fig. 15
Fig. 16
Fig. 17
Fig. 18
Fig. 19
Fig. 20,
Fig. 21.

Pa AUR exe.
Aspidodiadema antillarum A. Aa.

Specimen with spines, test 11 mm. in diameter, seen in profile.

Same with the spines cut off, seen facing an ambulacral area, showing the sheathed pedicellarie.

Portion of test of a specimen 11 mm. in diameter, seen from the actinal side ; denuded.

Portion of test of same as Fig. 3, seen from the abactinal pole ; denuded.

Actinostome, with termination of the adjoining ambulacral areas, showing the suckers, the gills,
and the large buccal tentacles of Fig. 2.

Portion of denuded test of specimen 11 mm. in diameter, seen facing one of the ambulacral
areas.

The same as Fig. 6, seen facing one of the interambulacral areas.

Denuded test of specimen 9 mm. in diameter, seen from the actinal side.

Genital ring of same, somewhat more magnified.

One of the sheathed ambulacral pedicellarie, greatly magnified.

Long-stemmed, long-headed trifid flexible pedicellaria, placed above ambitus.

Magnified view of a piece of the basal part of a primary radiole.

Large hyaline, globular, short-stemmed ambulacral spheridia, found near the abactinal system ;
magnified.

Smaller, long-stemmed actinal ambulacral spheridia ; magnified.

Young sheathed pedicellaria,

Small, short-headed, short-stemmed trifid ambulacral pedicellaria.

Actinostome of young Aspidodiadema measuring 5 mm. in diameter.

Genital ring and anal system of same specimen : neither the ocular nor the genital pores are as
yet formed in this specimen.

Young Aspidodiadema 6 mm. in diameter, seen from the actinal side: the primary spines are
cut off,

The same as Fig. 19, seen from the abactinal pole, showing the anal proboscis.

Genital ring of small Aspidodiadema 3.5 mm. in diameter: the genital pores are already

formed.

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Specimen covered with spines seen from the abactinal pole, natural size.

Denuded specimen, 23 mm. in diameter, seen from the abactinal side.

The same as Fig. 2, seen from the actinal side.

Abactinal system of same, somewhat more magnified.

Actinal system of same.

Magnified portion of test of same, seen facing one of the interambulacral areas.

Same as Fig. 6, seen facing one of the ambulacral areas.

Portion of test, seen facing one of the ambulacral areas, showing the suckers and the sheathed
pedicellarize.

One of the sheathed pedicellarix, greatly magnified.

The same, seen in profile.

Aspidodiadema denuded, seen in profile, 12 mm. in diameter.

The same as Fig. 10, seen from the abactinal pole.

The same as Fig. 10, seen from the actinal side.

Genital ring of same, somewhat more magnified.

Actinostome of same.

Portion of test of same, seen in profile, somewhat more magnified than in Fig. 10, seen facing

one of the ambulacral areas.

The same as Fig. 15, seen facing one of the interambulacral areas.

Young specimen 6 mm. in diameter, seen from the abactinal side,

The same as Fig. 17, seen in profile.

The same, seen from the actinal side.

Genital ring of a young specimen 3 mm. in diameter, before the formation of the genital or
ocular pores, showing the anal proboscis.

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PLATE X.
Phormosoma uranus Wry. THoMs.

Seen from the abactinal pole, fully expanded, natural size.

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Phormosoma uranus Wyy. THOMS.

Seen in profile, fully expanded, as it comes up in the trawl.
Denuded abactinal system of specimen about 170 mm. in diameter.
Actinal system of same.
Portion of test of actinal surface denuded, close to the ambitus.
Portion of test of median abactinal surface.
Figs. 2 and 3 are enlarged twice, all other figures natural size.

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PLATE XII.

Phormosoma placenta Wyv. THOMS.

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Seen in profile, natural size.

Same seen from the abactinal side.

Same seen from the actinal side.

Portion of actinal system denuded, magnified.

Coronal plates of the abactinal side, near the ambitus, magnified.

Edge of test, showing the ambital fasciole from the abactinal side, magnified.
Portion of test, facing the ambital fasciole, magnified.

One of the club-shaped spines of the actinal surface, magnified.

Denuded abactinal system, somewhat magnified.

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PLATE XIV.
Asthenosoma hystrix Wry. THoms.

Seen in profile, fully expanded as it comes up in the trawl.
Abactinal system of specimen about 160 mm. in diameter, denuded.
Actinal system of same, denuded, showing the arrangement of the actinal plates and the position
of the small digitate gills.
Portion of test of same, denuded, on the median actinal side.
Portion of test of same, denuded, on the median abactinal side.
Figs. 2, 3, (2) ; all others, natural size.

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1,2. Astropyga sp.

Abactinal system of young Astropyga 13 mm. in diameter.

Actinostome of same.

3-19. Phormosoma placenta Wrv. THoms.

Young Phormosoma 8 mm. in diameter, showing the abactinal system, and a part of the test.

Somewhat younger specimen 8 mm. in diameter, seen from the actinal side, showing the
spheridia, suckers, and pedicellaric of that side of the test.

Somewhat older Phormosoma 17 mm, in diameter, seen from the abactinal side of the test.

The same, seen from the actinal side.

Older specimen 20 mm. in diameter, seen from the actinal side.

The same, seen from the abactinal side.

Older specimen 28 mm. in diameter, seen from the abactinal side.

The same, seen from the actinal side.

Phormosoma 41 mm. in diameter, seen from the abactinal side.

The same, seen from the actinal side.

Portion of anal system of young Phormosoma, 22 mm. in diameter, showing the mode of

deposition of the limestone meshes forming the anal plates.

Figs. 14-19 show the gradual passage of mere accumulations of limestone cells, as in Vig. 14, which

indicate the first position of the future tubercles, to Figs. 16, 15, 17, 18, and 19, in which
the scrobicular ring, the mammary boss, and the perforation of the future tubercles are
little by little indicated.

Printed by A Meisel

A. Ag. & Roetter, del

Ps FAMT IE exe Vie.

Clypeaster subdepressus AGASss.

Fig. 1. Seen from above, natural size ; half the test denuded.

Fig. 2. The same, seen from the actinal side.

Fig. 3. Part of one of the median ambulacral zones of the actinal side, somewhat magnified.
Fig. 4, Part of one of the median interambulacral zones of the abactinal side, magnified.

5

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1,2. Clypeaster Ravenellii A. Aa.
Seen from the abactinal side, natural size, partly denuded.
Part of one of the ambulacral zones of the actinal side, magnified.
3,4. Clypeaster latissimus A. Ac.

Seen from the abactinal side, natural size; half the test denuded.
Part of one of the interambulacral zones of the abactinal side, magnified.

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1,2. Clypeaster Ravenellii A. Ac.
Seen from the actinal side, natural size, one half of the test denuded.
Part of one of the median ambulacral zones of the actinal side, magnified.
3,4. Clypeaster latissimus A. Ac.

Seen from the actinal side, natural size.
Part of one of the ambulacral zones of the actinal side, magnified.

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PLATE XVI.

Echinolampas depressa GRAY.

Fig. 1. Seen from above, denuded, natural size.

Fig. 2. The same, seen from the actinal side.

Fig. 3. The same, seen in profile.

Fig. 4. Actinostome, enlarged.

Fig. 5. Abactinal system, enlarged.

Fig. 6. Right anterior ambulacrum, enlarged.

Fig. 7. Interambulacral plates from the actinal side of the test.

Fig. 8. Left interambulacral plates from the area above the ambitus.
Fig. 9. Anal system.

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PLATE XVII.
Conolampas Sigsbei A. Aa.

Seen from the actinal side, denuded, natural size.

The same, seen from the interior of the test, natural size.
Abactinal system.

Actinal system, seen from the interior of the test.

The same as Fig. 4, seen from the actinal side.

Anal system.

j» Interior view of the same.

og”

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Portion of the right anterior ambulacrum.

A piece of the same seen from the interior of the test.

Plates of the lateral posterior interambulacral region of the median region of the test.
Plate of the lateral posterior interambulacral region of actinal side adjoining the ambitus.

PL XVI

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PLATE XVIII.
Paleopneustes hystrix A. Aa.

Left half of test covered with spines, seen from above, natural size.
Right half of test from above, denuded.

Abactinal system (2).

Same as Fig. 1, seen from actinal side, covered with spines.

Same as Fig. 2, seen from actinal side, denuded.

Actinostome (?), seen from actinal side.

Same as Fig. 6, seen from the interior.

Anal system (?).

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PLATE XIX.

Linopneustes longispinus A. Aa.

Fig. 1. Seen in profile (upper figure). Natural size.

Paleopneustes hystrix A. Aa.

Fig. 2. Seen in profile (lower figure).. Natural size.

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PLATE XX.

Linopneustes longispinus A. AG.

Richt half of test covered with spines from above, natural size.
Left half, denuded.

Abactinal system (3).

Same as Fig. 2, seen from the actinal side, covered with spines.
Same as Fig. 1, seen from the actinal side, denuded.

Actinal system (?).

Anal system with subanal fasciole (2).

Marginal fasciole on the edge of the ambitus.

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PLATE XXI.

Paleopneustes cristatus A. AG.

Lower extremity of the right anterior lateral ambulacrum of a specimen 150 mm. in length
and 85 mm. in height (4).

Part of test across the posterior part of the same ambulacrum at the ambitus (7).

Apical system of same (2).

Anal system of same (4).

Actinostome of same (4).

Part of test across the ambital region of the right anterior ambulacrum, to show part of the mar-
ginal fasciole of a specimen 85 mm. in length.

Young Paleopneustes cristatus, seen in profile (+).

Part of test (corresponding to Fig. 6) of same, magnified.

Young Paleopneustes cristatus 16 mm. in length, seen from the abactinal side.

The same as Fig. 9, seen in profile.

The same, seen from the actinal side.

Apical system of same, greatly magnified.

Actinostome of same, greatly magnified.

Anal system of same, greatly magnified.

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Fig. 2.
Fig. 3.
Fig. 4.

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PALATE X Xen.
Neolampas rostellata A. Aa.

Specimen 11 mm. long. diameter, denuded, seen from the abactinal pole (female).

The same as Fig. 1, seen from the actinal side.

The same, seen in profile.

The same, seen facing the anal extremity.

The same, seen facing the odd anterior ambulacrum.

Primary granulation of test of young specimen, 4 mm. long. diameter, arranged in indistinct
irregular lozenge-shaped figures.

Actinal termination of one of the lateral ambulacra, showing the five large, short-stemmed
globular spheeridia placed in the median ambulacral space of a specimen 12 mm. long. di-
ameter.

Magnified view of denuded actinostome of a specimen 11 mm. long. diameter.

Magnified view of actinal part of test, showing the suckers, spheridia, and primary spines and
tubercles of a specimen 6 mm. long. diameter.

Abactinal part of test of a female, showing the manner in which the genital openings are pro-
tected by spines, of a specimen 12 mm. long. diameter.

The same, denuded, showing the large genital openings and the pores of the madreporic body.

General view of the abactinal system and adjoining part of the test of a female about 11 mm.
long. diameter.

Denuded specimen, seen from above (male), 9 mm. long. diameter.

The same, seen in profile.

The same, seen facing the (anal system) posterior extremity.

The same, seen facing the odd anterior ambulacrum.

Greatly enlarged view of the abactinal system and adjoining part of the test of the same speci-
men as Fig. 13.

Greatly enlarged view of actinostome of same.

Young male specimen, denuded, seen from the abactinal side, 4.5 mm. long. diameter.

The same, seen in profile.

The same, seen facing the posterior (anal) extremity.

Enlarged view of anal groove of a specimen abont 12 mm. long. diameter.

Young specimen (measuring 2.5 mm. long diam.) covered with spines, seen from the actinal side.

The same, seen from the abactinal side.

Plates of anal system.

Head of short-stemmed trifid actinal ambulacral pedicellaria.

Long-stemmed, long-headed trifid coronal pedicellaria.

Young miliary spine, with spiny cupuliform extremity.

Minute short-stemmed ellipsoidal spheridia.

Anal pyramid, composed of eight large triangular plates, of a young specimen 4 mm. long.
diameter.

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PLATE XXIII

1-4. Rhinobrissus micrasteroides A. Aa.

Seen in profile, covered with spines.
Same, seen from the actinal side.
Seen from above, denuded.

Seen facing the posterior extremity.

Figs.1-4 from a specimen 23 mm. in long. diameter.

5-14. Paleotropus Josephine Lovin.

Seen from above, covered with spines.

Same, seen from the actinal side.

Denuded specimen, about the same size, seen from the abactinal side.
Same, seen from the actinal side.

Same, seen in profile.

Same, seen from the anterior extremity.

Same, seen from the anal extremity.

Magnified view of abactinal system of same.

Magnified view of anal system.

Magnified view of actinal system.

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Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5,
Fig. 6.
Fig. 7.
Fig. 8.
Fig. 9.
Fig. 10.
Fig. 11
Fig, 12
Fig. 13
Fig. 14
Fig. 15

PLATE XXIV.

1-5. Echinolampas depressa Gray.

Young specimen, seen from above, 5 mm, long. diameter.
The same, seen in profile.

The same, seen from the actinal side.

The actinostome of same.

The anal system of same.

6-15. Palezobrissus Hilgardi A. Aa.

Seen from above, covered with spines.

The same, from the actinal side.

The same, in profile.

Same as Fig. 7, denuded.

Same as Fig. 6, denuded.

Same as Fig. 8, denuded.

Same, seen facing the anal extremity. Figs. 6-12, natural size.
Actinostome of Fig. 9, enlarged.

Anal system, enlarged.

Apical system, enlarged.

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PLATE XXV.
Agassizia excentrica A. Aa.

Seen in profile, covered with spines, 20 mm. long. diameter.

A specimen of the same size, seen in profile, denuded.

The same, seen from the actinal side.

The same, seen from the abactinal side.

The same, seen facing the odd anterior ambulacrum.

The same, seen facing the anal system (posterior extremity).

Young Agassizia, 7 mm. long. diameter, seen in profile.

The same, seen facing the anal system.

The same, from the abactinal pole.

The same, seen from the actinal side. 3

Enlarged abactinal system, with adjacent part of test of a small specimen 6.5 mm. long.
diameter.

Abactinal system of a young Agassizia, 3 mm. long. diameter.

Actinal system of same.

Magnified miliary spines of the lateral fasciole.

One of the large ambulacral suckers of the odd anterior petaloid ambulacrum, expanded, from
a specimen 11 mm. long. diameter. :

Four ambulacral suckers from same, of the outer petaloid part of the odd anterior ambulacrum,

somewhat contracted.

A Ag & Roetter, del

Printed by A Meisel

PLATE XXVI.

1-3. Urechinus naresianus A. AG.

Fig. 1. Actinostome of specimen 33 mm. long. diameter.
Fig. 2. Abactinal system and adjoining part of test of same.
Fig. 3. Anal system and adjoining part of test of same.

4. Rhinobrissus micrasteroides A. Aa.

Fig. 4, Specimen 32 mm. long. diameter, seen from the abactinal side.

5,6. Schizaster (Periaster) limicola A. Aa.

Fig. 5, Anal system of specimen 68 mm. long. diameter.
Fig. 6. Apical system, with surrounding part of test of same.

7-18. Brissopsis lyrifera Acass.

Fig. 7. Elongated type, seen from the abactinal side, natural size.

ig. The same, seen in profile.

Fig. 9. Enlarged view of posterior extremity of test, showing the anal system and fasciole, with the
subanal fasciole.

Fig.10, Portion of lateral interambulacral part of test near the ambitus.

Fig. 11. Portion of posterior lateral ambulacral zone.

Fig. 12. Portion of anterior lateral ambulacral zone.

Fig. 13. Globular type of the species, seen from the abactinal pole, natural size.

Fig. 14. The same, seen in profile.

Fig. 15. Posterior part of test of same, enlarged, corresponding to Fig. 9 in the elongated type.

Fig. 16, Corresponds to Fig. 10 of the elongated type.

Fig. 17. Corresponds to Fig. 11 of the elongated type.

Fig. 18. Corresponds to Fig. 12 of the elongated type.

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PLATE, XxeVen:
Macropneustes spatangoides A. Aa.

Seen in profile, natural size.

Another specimen, seen from the abactinal side, natural size.

Enlarged view of actinostome of same.

Enlarged view of the reticular peripetalous fasciole of the specimen of Fig. 2.

Enlarged view of anal system and subanal fasciole of the same.

Profile outline of a large specimen, with high posterior extremity, natural size.

The same, seen {rom the abactinal pole ; the apical part of the petaloid ambulacra has become

atrophied, as is so frequently the case in allied genera.

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Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.
Fig. 7.
Fig. 8.
Fig. 9.
Fig. 10.
Fig. 11.
Fig. 12.
Fig. 13.
Fig. 14.
Fig. 15.

Fig. 16.

PLATE XXVIII.

1-7. Schizaster orbignyanus A. Aa.

Denuded specimen, natural size, seen in profile.

The same, seen from the abactinal pole.

The same, seen from the actinal side.

Anal system of subanal fasciole of same.

Specimen covered with spines, natural size, seen from the abactinal side.

Profile (natural size) of posterior extremity of a specimen intermediate between Figs. 1 and 5.
Anal system of same, with subanal fasciole, somewhat enlarged.

8-14. Schizaster fragilis AGass.

Young Schizaster, seen in profile, 23 mm, long. diameter.

Anal system of same, enlarged.

Somewhat younger Schizaster than Fig. 8, 10 mm. long. diameter, seen in profile.

Anal system of same, with its subanal fasciole.

Still younger specimen, only 6 mm. long. diameter, seen in profile.

Anal system and adjoining part of test of same.

Extremity of the petaloid right anterior ambulacral petal, with its adjoining fasciole, of a speci-
men about 55 mm. long. diameter.

15, 16. Schizaster canaliferus AGAss.

The extremity of the left petaloid ambulacrum of a specimen measuring 70 mm. long. diam-
eter.

The anal system and fasciole of same.

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