HARVARD UNIVERSITY

Library of the

Museum of

Comparative Zoology

Please substitute the cover and title enclosed for those
sent in November, igo8, as an error in numbering the plates
for a future volume of the Memoirs necessitates a change
from Vol. XXXVI to Vol. XXXIX for the Report on the
Genus Colobocentrotus.

"T^tr^wT?' ^^/^U^^^2^

Itmotrs of i\n gluseum of Comparatibi ^oologg

AT HARVARD COLLEGE.

Vol. XXXAZ^ No. 1. JJL

REPORTS ON THE SCIENTIFIC RESULTS OF THE EXPEDITION TO THE
TROPICAL PACIFIC, IN CHARGE OF ALEXANDER AGASSIZ, BY THE
U. S. FISH COMMISSION STEAMER "ALBATROSS," FROM AUGUST,
1899, TO MARCH, laOO, COMMANDER JEFFERSON F. MOSER, U. S. N.,
COMMANDING. MCZ

XL LfBRA~?Y

ECHINL *"'^^''™

HA'^VARD
THE GENUS COLOBOCENTROTUy.^'V^f^^^TY

By ALEXANDER AGASSIZ.

WITH FORTY-NINE PLATES.

[Published by Permission of George M. Bowers, U. S. Commissioner of Fish and Fisheries.]

CAMBRIDGE, U.S.A.:

^rintElr for the Jluscum,

November, 1908.

TROPICAL PACIFIC.

The folloxoing Publications of the Museum contain Reports on the Dredging Operations in
charge of Alexander Agassiz, of the U. S. Fish Commission Steatner '■^Albatross,'' during
1899 and 1900, Commander Jefferson F. Moser, U. S. N., Commanding.

I. A. Agassiz. Preliminary Report and List of Stations. With Remarks ou the Deep-Sea
Deposits by Sir John Murray. Mem. M. C. Z., Vol. XXVI. No. 1. January, 1902.
114 pp. 21 Charts.

II. A. G. Mayer. Some Species of Partula from Tahiti. A Study in Variation. Mem. M. C. Z.,
Vol. XXVI. No. 2. January, 1902. 21 pp. 1 Plate.

III. A. Agassiz and A. G. Mayer. Medusas. Mem. M. C. Z., Vol. XXVI. No. 3. January,

1902. 40 pp. 13 Plates, 1 Chart.

IV. A. Agassiz. The Coral Reefs of the Tropical Pacific. Mem. M. C. Z., Vol. XXVIII.

February, 1903. 33, 410 pp. 238 Plates.

V. C. R. Eastman. Sharks' Teeth and Cetacean Bones from the Red Clay of the Tropical
Pacific. Mem. M. C. Z., Vol. XXVI. No. 4. June, 1903. 14 pp. 3 Plates.

VI. W. E. HoYLE. Cephalopoda. Bull. M. C. Z., Vol. XLIII. No. 1. March, 1904. 71pp.
12 Plates.

VII. H. LuDwiG. Asteroidea. Mem. M. C. Z., Vol. XXXII. July, 1905. 12, 292 pp. 35
Plates, 1 Chart.

VIII. W. E. RiTTER and Edith S. Byxbee. The Pelagic Tunicata. Mem. M. C. Z., Vol. XXVI.
No. 5. August, 1905. 20 pp. 2 Plates.

IX. Mary J. Rathbun. The Brachyura. Mem. M. C. Z., Vol. XXXV. No. 2. August,
1907. 54 pp. 9 Plates.

X. C. H. Gilbert. The Lantern Fishes. Mem. M. C. Z., Vol. XXVI. No. 6. July, 190a
23 pp. G Plates.

XL A. Agassiz. Echini : The Genus Colobocentrotus. Mem. M. C. Z., Vol. XXXYJ. No. 1.
November, 1908. 8, 33 pp. 49 Plates. ^

lemorrs of tijt Htuscum of fi^amparalibt iodlogg

AT HARVARD COLLEGE.

Vol. XXX^. No. 1. 7X-

REPORTS ON THE SCIENTIFIC RESULTS OF THE EXPEDITION TO THE
TROPICAL PACIFIC, IN CHARGE OF ALEXANDER AGASSIZ, BY THE
U. S. FISH COMMISSION STEAMER "ALBATROSS," FROM AUGUST,
1899, TO MARCH, 1900, COMMANDER JEFFERSON F. MOSER, U. S. N.,
COMMANDING.

XI.

ECHINI.

THE GENUS COLOBOCENTROTUS.

By ALEXANDER AGASSIZ.

"WITH FORTY-NINE PLATES.

[Published by Permission of Georqb M. Boweks, D. S. Commissioner of Fisli and Fisheries.]

CAMBRIDGE, U.S.A.:

^rintctr for tfje lEuseum.

NoVEJVUiEK, 1908.

/

CONTENTS.

REPORTS ON THE SCIENTIFIC RESULTS OF THE EXPEDITION TO THE
TROPICAL PACIFIC, in charge of Alexander Agassiz, by the U. S. Fish Com-
mission Steamer "Albatross," from August, 1899, to March, 1900, Commander
Jefferson F. Moser, U. S. N., Commanding. XI. Echini: The Genus Colobo-
CENTROTUS. By Alexander Agassiz. With viii., 33 pp. and 49 Plates.

TABLE OF CONTENTS.

Page

Note vii

Colobocentrotus Brandt 1

Colobocentrotus Mertensii Br. . 1

Colobocentrotus Stimpsoni A. Ag. . 1

Podophora Agass 2

Podophora atrata Agass 2

Podophora pedifera Agass 2

Colobocentrotus and Podophora . . 3

Colobocentrotus Mertensii Br. ; Plates
2, figs. 8-lS; 3% figs. 9-11; 30, 32,
//z./ figs- 5-S ; 35, 36, 39, figs. -s^tt^/

' ^ -^ 45, figs. 6-10 ■ 7

/ Colobocentrotus Stimpsoni A. Ag. ;

Plates 2, figs. 4-7 ; 29, 32, figs. 1-4 ;

-2 - M 33, 34, 37, 38, 39, figs. ^i-S-; 40-45,

figs. 1-5 9

Page
Podophora atrata Agass. ; Plates 2,

figs. 1-3; 3% figs. 5-S; 16, figs.

9-14; 17-28, 31, figs. 5-8 ... . 14

Podophora pedifera Agass. ; Plates 1,

3^ figs. 1-4; 4-16, figs. 1-8; 31,

figs. 1-4 19

The Lanterns and Auricles of Colobocen-
trotus and Podophora ; Plates 13-15,
26-28, 44 25

The Spicules of the Pedicels ; Plates
16, 46 26

The Pedicellariae ; Plates 3»-6 ; 17-19 ;
29, 30 27

The Sphseridia, Plates 31, 32, and Cysta-
canths, Plates 1-3 30

NOTE,

A small number of sea-urchins were collected during the Tropical Pacific
Expedition of the "Albatross" (1899-1900), so that only a few genera and
species characteristic of the Pacific will be described in succession whenever
sufficient new and interesting or important material has been obtained.

The genus Colobocentrotus of Brandt remarkable for its peculiar primary
radioles forms the subject of the first part of the Tropical Pacific Echini.
This will be followed by a paper on the allied genus Heterocentrotus.

I have to thank Mr. Richard Rathburn of the Smithsonian for having sent
me for study the types of Colobocentrotus collected at the Bonin Islands, by
Dr. Wm. Stimpson, the naturalist of the North Pacific Exploring Expedition
under command of Captains Ringgold and Rodgers.

I am greatly indebted to Mr. Magnus Westergren for the interest he has
taken in the preparation of the Plates illustrating this Memoir. His accuracy
in drawing, his knowledge of the structure of sea-urchins obtained during his
long training in the preparation of plates on Echinoderms, is shown on every
plate due to his facile pencil.

In addition to the material of Colobocentrotus collected by the " Alba-
tross " during the Tropical Pacific Expedition I have availed myself of mate-
rial collected by the " Albatross " at the Hawaiian Islands and in other parts
of the Pacific and in the Indian Ocean, found in the collections of the Museum
of Comparative Zoology.

Alexander Agassiz.

Newport, R. I., August 29, 1908.

TROPICAL PACIFIC ECHINI.

THE GENUS COLOBOCENTROTUS.

CoLOBOCENTROTUs Brandt (A. Ag. emend.).

Colobocentrotus Brandt, 1835, Prod. p. 66.
Colobocentrotus A. Ag. Rev. Echini, p. 423 (partim).

This genus is now limited to such species as Colobocentrotus Mertensii
Brandt and Coloh. Stimpsoni A. Ag., the better known species, C. atratus and
C. piedifer, having been separated from it and united in the genus Podophora
Agass.

The following are the species of Colobocentrotus and of Podophora
described in this memoir :

Colobocentrotus Mertensii Brandt.

Colobocentrotus Mertensii Brandt, 1835, Prod., p. 66.

Colobocentrotua Mertensu A. Ag. (partim) Rev. Echini, 1872, p. 103, PI. IIP, figs. 4, 5,

p. 426. Bonin Islands.
Colobocentrotua Leskei A. Ag. 1863. Proc. Phila. Acad. p. 354 is a slip of the pen for

Colobocentrotus Mertensii Brandt.
Colobocentrotus quadriseriatus Trosch., noted by Troschel as occurring in Australia, is, I

should say from his description, Colob. Mertensii Brandt.

This species was collected by Dr. Wm. Stimpson at Port Lloyd, Bonin
Islands, North Pacific Exploring Expedition, under Captains Ringgold and
Rodgers, It is figured in the Revision of the Echini, Plate III'', figs. 4, 5.

Stimpson says it is found " in surf-washed rocks."

Colobocentrotus Stimpsoni A. Ag.^ ^ u "J^-V^' /

Is the large grayish pink species collected by Dr. Stimpson at the Bonin
Islands, North Pacific Exploring Expedition, and described later on.

The species of Colobocentrotus have thus far only been collected at the
Bonin Islands and, according to Troschel, in Australia.

TROPICAL PACIFIC ECHINI.

PoDOPnoRA Agass.

Podophora Agass. 1840, Cat. Syst. Ectyp., p. 19.

In 1840 Agassiz was not aware of the existence of Brandt's Prodromus
where the genus Colobocentrotus was established.

Podophora atrata Agass.

Echinus atratus Lin. 1758, Syst. Nat. ed. X., p. 655. ^ ^ . .^ , , ,

Echinometra atrata Blainv., ISs/, A«tiaeVp^^25r^»ir-2er*gSv-4r4a, ^cT .^C^ • ^ o-^ .^f^ \^^ ,Y ^ ^ ^

Podophora atrata Agass. 1840, Cat. Syst. Ectyp., p. 19.

Colobocentrotus atratus A. Ag. (partirn), 1872, Rev. Echini, p. 102, PI. Ill*, fig. 3.

Colobocentrotus atratus Mobius, 1908, Aesthetik d. Thierwelt, fig. 5, p. 20.

Loven in his Echin. of Lin. says that the type of Linnjeus was collected at
Mauritius, or rather that the original of the figure in the French edition of
Klein to which Linnteus refers in his twelfth edition came from Mauritius.
Leske's figure, to which Blainville and others refer as the typical atratus, has
the longer marginal spines rounded at the tip. Blainville further states that it
is "d'un blanc violet presque noir," which agrees with the coloring of the spe-
cimens from the Hawaiian Islands and Mauritius in the Museum collections.

Hawaiian Islands, M. C. Z. collections.

Hilo, Hawaii, Smithsonian (Albatross coll.).

Mauritius, Seychelles, Zanzibar, M. C. Z. collections. This species has also
been noted as occurring at Java and the Moluccas. *

Mobius has given an excellent figure of Podcqjhora atrata from Mauritius,
the dark violet species with long spines rounded at the tip. Echinometra
Quoyi Blainv. is only the young of F. atrata. Colob. Leskei Br. is probably
P. atrata.

Podophora pedifera Agass.

Echinus pedifer Blainv. 1825, Diet. Sc. Nat. 0., Vol. 37, p. 97. Mers Australes.

Podophora pedUera Agass., 1846, C. Rais. Ann. Sc. Nat. VI, p. 370. ^^

Podophora atrata A. Ag. (partim), 1872, Rev. Ech. p. 102, PL IIP, fig. 3, p. 424.

The excellent description of Blainville, with his statement " couleur gen6-
rale d'un vert bleuatre, les mammelons verts, les epines livides," leaves no
doubt of its identity with the greenish-olive specimens collected at Fakarava

» See Rev. Echini, 1872, p. 103.

THE GENUS COLOBOCENTROTUS. 3

by the "Albatross" Tropical Pacific Expedition 1899-1900, on the seaface of
the reef exposed to the full force of the surf.

A specimen from Chili is figured in the Revision of the Echini (PI. IIP,
fig. 3). There are also specimens of this species in the Museum collections
labelled Valparaiso ?, Callao, Chili, and Peru.

COLOBOCENTEOTUS AND PoDOPHORA.

The genus Colobocentrotus was established by Brandt in 1835 ; he also in-
cluded in \i Podophora atrata Agass., for which Agassiz in 1840 established the '^'CJU /
genus Podophora. With the material at my disposal I have come to the con-
clusion that the original Colobocentrotus of Brandt may be dismembered into
two genera, — the one (Podoj^hora Agass.) to include P. atrata and P.pedifera
(Pis. 7; 20); the other (Colobocentrotus Brandt) limited to Coloh. Mertensii
and Coloh. Stimj^soni, the former of which was the first species for which
Brandt originally established the genus (Plates 33; 34; 37; 38; and 35; 36).

The species of Colobocentrotus (Plates 33, fig. 3 ; 34, fig. 3 ; 35, fig. 3 ; 36,
fig. 3) are much flatter than those of Podophora. They are at once distin-
guished by the elongated coronal plates which carry a larger number of
primary tubercles uniform in size (arranged in two horizontal rows) in
both the ambulacral and interambulacral zones than in the species of
Podophora. There are as many as twelve vertical rows of interambulacral
tubercles immediately above the ambitus in Coloh. Stimpsoni in a specimen
of 65 mm. in diameter ; in a specimen of Podopliora pedifera of 55 mm.
there are eight, and in a specimen of Podopliora atrata of 45 mm. there are
only six vertical rows at the ambitus.

The outline of the test of the species of Colobocentrotus is elliptical or
circular, while it is pentagonal in Podophora. The general shape of the test
of the species of Colobocentrotus and Podophora seems to be fairly constant.
An outline of the ambitus of each of the four species (see figs, a-d p. 5), with
their measurement and number of pores in the ambulacral plates ^n the
abactinal side, is given for comparison.

Podophora pedifera Agass.

Length, denuded, 55 mm.
Width, denuded, j^mm. ^ V/

Height, denuded, 30 mm.
Pairs of pores in each ambulacral plate 11, 12, near the ambitus on the
abactinal side.

4 TROPICAL PACIFIC ECHINI.

Podophora atrata Agass.

Length, denuded, 45 mm.
Width, denuded, 38 mm.
Height, denuded, 18 mm.
Pairs of pores in each ambulacral plate 9, 10, near the ambitus on the
abactinal side.

Colobocentrotus Stimpsoni A. Ag.

Length, denuded, 64 mm.
Width> denuded, 53 mm.
Height, denuded, 24 mm.
Pairs of pores in each ambulacral plate 7, 8, near the ambitus on the
abactinal side.

Colobocentrotus Mertensii Brandt.

Length, denuded, 54 mm.
Width, denuded, 48 mm.
Height, denuded, 22 mm.
Pairs of pores in each ambulacral plate 7, 8, near the ambitus on the
abactinal side.

The outline at the ambitus of Podophora pedifera (Fig. a ; PI. 13, fig. 1)
and of Podophora atrata (Fig. h; PL 25, fig. 5) Ls pentagonal in both; the
actinal side of Podophora pedifera is strongly arched, while that of Podophora
atrata is nearly flat. The ambitus of Colob. Stimp)som is ellipsoidal (fig. d), in
Colob. Mertensii it is almost circular (fig. c). This dissimilarity can scarcely
be due to age, as the difference in length of the two specimens is only 10 mm.
The number of tubercles in Cohb. Mertensii is less than in Colob. Stimpsoni.
In Mertensii those in the interambulacrum at the ambitus, on the actinal
side, are somewhat larger ; hence that side is more concave.

Photography is often, misleading when reproducing specimens of natural
size, some parts are apt to be somewhat out of focus. The profiles in Plates
8, fig. 3; 20, fig. 6; 34, fig. 3; and 36, fig. 3, do not fully correspond to the
diagrams (figs, a-d) which are correct.

A comparison of the odd anterior ambulacrum of the two species of Podo-
phora (PI. 46, figs. 1, 5), and of Colobocentrotus Stimpsoni (PI. 46, fig. 9)
brings out strikingly their specific differences. In a specimen of Podophora
pedifera Agass. of 55 mm. in diameter the ambitus crosses the fifth and sixth

THE GENUS COLOBOCENTROTUS.

plate, and the greatest width of the poriferous field is at the second and third
plate from the aetinostome, leaving a comparatively narrow interambulacral field
(PI. 12, fig. 1). From the ambitus to the abactinal system the large tubercles

Fig. a. P. pedifera.

Fig. b. P. atrata

occupy the whole of the ambulacral plate, leaving room only for a thin line of
small miliaiies. The abactinal tubercles alone have a circular scrobicular
area ; from the fourth plate from the apex it becomes irregular in outline,

Fig.

Coloh. HJerlensii.

Colob. Stiiiipsoni.

and the pairs of pores are sometimes pushed in two arcs, or forced out towards
the outer edge of the ambulacral plate. At the ambitus and on the actinal
side the primary tubercles form two short rows on each side of the primary rows
and then extend towards the aetinostome as a single row of small secondaries

6 TROPICAL PACIFIC ECHINI.

with a few miliaries on each side of the median line separating the two porif-
erous fields. The difference in appearance of the pores of the actinal edge of
the poriferous field of the region at the ambitus and those of the abactinal side
of the ambulacral system is shown on PI. 46, figs. 2, 3, J,..

The odd anterior ambulacrum of a specimen of Podophora atrata meas-
uring 46 mm. in diameter is at once distinguished from that of Podophora
pedifera by the more regular outline of the vertical rows of primary tuber-
cles. Both the mammary boss and scrobicular area are circular in outline
(PI. 46, fig. 5) ; they occupy a smaller arc of the ambulacral plates, having a
larger space free from miliaries along the median line of the ambulacral zone.
There are here and there a few small secondary tubercles in the inner angles
of the ambulacral plates.

The vertical rows of primary tubercles extend as small tubercles to the
edge of the actinal system, and numerous minute secondaries and miliaries are
intercalated between the pairs of pores of the poriferous field. This is compar-
atively narrower than that of Podophora jicdifera, leaving a much broader
actinal interambulacral zone to separate the poriferous fields of adjoining
ambulacra (PI. 24, fig. J) than in Podophora pedifera. The change in the
pairs of pores as we pass from the actinal edge to the ambitus and to one
of the abactinal pairs of pores are seen in PI. 46, figs. 6, 7, 8.

In a specimen of Colobocentrotns Stimpsoni measuring 65 mm. in longest
diameter the primary tubercles above the ambitus are of nearly the same
size with a circular mammary boss and scrobicular area (PI. 46, fig. 9), those
at the ambitus being slightly larger and those on the actinal side of the ambi-
tus decidedly larger. In these the mammary boss and the scrobicular area are
somewhat elliptical. The abactinal primary tubercles form above the ambitus
four slightly undulating vertical rows with small miliaries on both sides of
the median line and miliaries between the outer and inner vertical rows.
Below the ambitus there are four irregularly placed large primary tubercles
with a somewhat smaller one, and below that two vertical rows of small, dis-
tant secondaries on each side of the median line extending to the actinal
system, with numerous miliaries and minute secondaries filling the spaces
between the pairs of pores of the poriferous field.

On the abactinal side of the test there are usually three large tubercles on
each plate ; near the abactinal system they are reduced to two or to one with
a small secondary. The poriferous arcs occupy the outer part of the
ambulacral plates. There are eight pairs of pores arranged in a very open

THE GENUS COLOBOCENTEOTUS. 7

horse-shoe shape and at the ambitus they are beginning to be crowded out of
place to form the actinal poriferous field. PI. 46, fig. 10 is a pair of pores from
the poriferous field, fig. 11 a pair of pores at the ambitus, and fig. 12 one of
the pores of the twelfth ambulacra! plate, counting from the actinal system. -iyCc-xro-uJ^

CoLOBOCENTROTUS Brandt (A. Ag. emend.)

Colobocentrotus Mertensii, Brandt.

Pis. 2, figs. 8-13 ; 3% figs. 9-11 ; 30 ; 32, figs. 5-8 ; 35 ; 36 ; 39,
/_7_/ figs.tM-; 44; 45, figs. G-IO.

I Colobocentrotus Mertensii differs from Coloh. Stimpsoni in having a more
circular outline (PI. 36, figs. 1, 2) and being less depressed (PI. 36, fig. 3).
It has a proportionally larger actinal system (PI. 36, fig. 1). The actinal
surface is more sunken than that of Colob. Stimpsoni. The ambital edge
both of the ambulacra! and interambulacral zones carries much larger prim-
ary tubercles (PI. 36, figs. 1, 3) than those of Coloh. Stimpsoni. The actinal
lips are broad ; the actinal plates of the interambulacral areas are narrower
than those of Colob. Stimpsoni. The actinal interambulacral zone carries four
irregular, vertical rows of most distinct small secondaries larger than in the
corresponding zones of Colob. Stimpsoni.

The poriferous fields are broad, slightly sunken ; the median line of the small
distant ambulacral primaries consists of two vertical rows also larger than
those of Colob. Stimpsoni. The poriferous field is studded with minute miliaries
and small secondaries.

The arrangement of the miliaries on the buccal plates and of the cluster of
narrow crescent-shaped plates of the actinal system (PI. 36, fig. 1), does not
differ materially from that of Colob. Stimpsoni (PI. 38, fig. 1). The five pairs
of poriferoas buccal plates are somewhat larger in Coloh. Stimpsoni than in
Coloh. Mertensii. At the ambitus there are two rows of eight large primary
interambulacral tubercles. These rapidly taper to four rows of small tubercles
towards the actinal system ; on the abactinal side the primary interambu-
lacral tubercles diminish gradually to the second or third plate from the am-
bitus and then remain of nearly uniform size, diminishing most gradually
towards the abactinal system. At the fourth plate from the apex there are
but six primary tubercles to each interambulacral plate, arranged in two hori-
zontal rows ; while nearer the ambitus there are eight or ten similarly arranged.
The intertubercular space is filled with miliaries (PI. 36, figs. 2, 3).

8 TKOPICAL PACIFIC ECHINI.

In the ambulacra! zone there are four vertical rows of large primary
tubercles at the ambitus. These gradually diminish in size towards the abao-
tinal system. On each ambulacral plate there are three primary tubercles,
two, one above the other, along the rnedian ambulacral line, the other on the
distal side of the plate, surrounded by the poriferous arc. This consists of
seven pairs of pores, while there are eight in Colob. Stimpsoni. The intertu-
bercular space is filled with miliaries.

The abactinal system is more raised than in Colob. Stimpsoni, and it is
covered by a coarser tuberculation of small secondaries (PI. 36, fig. 2), The
anal system is deeply sunken ; the genital pores are slightly larger than those
of Cohb. Stimpsoni. There are from ten to twelve closely packed tubercles
on the genital plates, and three on the ocular plates. The madreporic body
occupies the two sides of the distal part of the right anterior genital ; the
proximal part adjoining the anal system carries a few small secondaries and
miliaries.

Colohoceiitrotus Mertensii, when covered with spines (PI. 35) is of a
darker ash color than Colob. Stimpsoni. The actinal spines of the former,
corresponding to the longer small primary tubercles of that region, are longer
and larger (PL 35, fig. 1) than those of Colob. Stimpsoni (PI. 33, fig. 1), and
the large, flat, truncated radicles are more numerous at the ambitus than in
Colob. Stimpsoni.

In Colob. Mertensii, the primary radioles of the abactinal side of the test

are larger than those of Cohb. Stimpsoni (compare PI. 35, figs. 2, 3 with PI. 33,

/i / 2.-3/ fig-"'^) and are also more distant, giving a freer circulation of water round

/ / the spines to the miliaries and pedicellarioe of the intertubercular areas. The

small radioles covering the abactinal system (PI. 35, fig. 2) are more pointed

than those of the abactinal system of Colob. Stimpsoni (PI. 33, fig. S).

The order of appearance of the vertical rows of primary tubercles of Colob.
Merteiuii is shown on PI. 39, figs. 1, 2, which represent the arrangement of
the radioles (fig. 1) in the right posterior ambulacrum, with the right poste-
rior interambulacrum and a part of the right anterior ambulacrum. Fig. 2
shows the arrangement of the radioles of the odd posterior interambulacrum,
with the bivium and half of the right posterior ambulacrum.

THE GENUS COLOBOCENTROTUS. 9

Colobocentrotus Stimpsoni A. Ag.^ '^^ ^7-— j/Uy

Pis. 2, figs, lt-1 ; 29 ; 32, figs. 1-k ; 33 ; 34 ; 37-39, figs.^-^; ^4/

40-45, figs. 1-5. '

A specimen of Coloh. Stimpsoni, measuring 65 mm. when denuded, shows
its elliptical outline (Pis. 34, figs. 1, 2 ; 38, figs. 1, 2). The abactinal system
is slightly raised ; the anal system sunken ; the poriferous zone is somewhat
sunken, and the genital pores are deeply sunken. The mamelon of the abac-
tinal primary tubercles is glossy, and the general appearance of this species,
when seen from above, is that it is covered with a most uniform tuberculation
diminishing but slightly in size towards the apical system. Immediately at
the ambitus and on both sides of it are placed the horizontal rows of the
largest primary tubercles (Pis. 34, figs. 1, 3; 38, figs. 1, 3). A profile view
(Pis. 34, fig. 3 ; 38, fig. 3) shows the nearly flat actinal side and low, subconi-
cal arched test. A view from the actinal side (Pis. 34, fig. 1 ; 38, fig. l)
shows that the actinal surface of the test is flat, the ambital edge being
slightly raised. The poriferous fields are wide, extend to the ambitus, and
are separated by the comparatively narrow interambulacral zone. The two
median vertical rows of small ambulacral tubercles extend to the actinostome.
Two still smaller additional rows of secondary tubercles run across the porif-
erous field about half way between the median line and the outer edge of the
poriferous zone.

Seen from the interior of the test the interambulacral plates show a well
marked groove in the middle of the suture of adjoining plates which is not
shown in the drawings owing to the absence of shading, and the poriferous
zone is raised well above the general level of the remaining part of the
ambulacral plates (PI. 42, fig. 1).

Owing to the flatness of the test of Colob. Stimpsoni and the sharp angle
made by the ambitus between the abactinal and actinal sides the coronal
plates at the ambitus are greatly compressed and the plates very narrow
(see PI. 42, fig. 1), this is also seen in the compression of one of the ambulacral
ambital plates (PI. 42, fig. 7) in which the sutures between the demi-plates
carrying the pairs of pores are practically obliterated. Compare this with an
abactinal plate, the tenth from the actinal system (PI. 42, figs. 5, 6), in which
(fig. 7) the sutures of the demi-plates of the eight pairs of pores are sharply
defined.

In a view of the abactinal part of the ambulacral system, seen from the

10 TROPICAL PACIFIC ECHINI.

interior of the test (PL 42, fig. 8, and PI. 43, fig. 3), it is easy to see the struc-
ture of the upper arabulacral plates. Each plate is made up of a narrow plate
reacliing from the median line to the outer edge of the plate and of a
larger plate into which run from the outer edge half way to the median line
seven demi-plates carrying seven pairs of pores. In the tenth plate from the
actinostome in which the eight pairs of pores are only slightly crowded to one
side (PI. 42, fig. 5), we see the arrangement of the three large primary
tubercles and the intertubercular space occupied by the miliaries and small
secondaries. A view from the inside of 4hc left }303tcrior ambulacrum shows "^ JU_
the sutures indicating the composite structure of the ambulacra! plate '

(PI. 42, fig. 6). In the narrow upper plate the pores marked with a small x
correspond to the upper pair of pores of PI. 42, fig. 5, also marked with an x
and on the same figure we can trace the suture of the demi-plates of the seven
other pairs of pores forming the poriferous arc which extend half way from
the outer edge towards the median ambulacral sutures.

In an exterior view from the actinal side of the poriferous field of the odd
anterior ambulacrum (Pis. 34, fig. 1; 38, fig. 1; 42, fig. 3) it is impossible
to detect either the sutures of the primary plates or of the demi-plates ; but in
a view from the interior (PI. 42, fig. .4) the peculiar shape assumed by the
primary actinal ambulacral plates and demi-plates, owing to the crowding and
compressing of the poriferous plates is shown in Plate 42, fig. 4. The
pores marked with x in fig. 4 in the two ambulacral plates correspond to the
pairs of pores similarly marked on PL 42, fig. 3. The poriferous field is
marked by the number of miliaries and small secondary tubercles interspersed
between the pairs of pores. (PL 42, fig. 3.)

The outline of one of the pairs of poriferous buccal plates of Colob. Stimp-
soiii is shown on PL 42, fig. 2. They each carry a few miliaries and a num-
ber of small secondaries. The plates are originally elliptical ; they abut in
older specimens.

Owing to the thickness of the test the passage for the tubes leading to
the pedicels slants very considerably and distant pairs as seen from the inte-
rior on figs. Jf, 6, PL 42, are thus brought closely together on the exterior side
of the test figs. 3, 5, PL 42.

In figs. 3, 4, 5, 6, of PL 42, the two minute crosses indicate the position
of the pairs of pores on the inner and outer faces of the test ; figs. 3, 4- on the
actinal part of the poriferous field of the odd anterior ambulacrum and figs.
5, 6 of a pair of pores of the abactinal part of the odd anterior ambulacrum of

THE GENUS COLOBOCENTEOTUS. 11

Colohocentrotus Sfimpsoni. These figures show how the distant openings for
the pedicels slant across the thickness of the test to come together and form
the pairs of pores.

On PI. 41, fig. i, is given a figure of the left anterior interambulacrum of a
specimen of Colob. Stimpsoni, measuring with its spines 88 mm. in diameter
with 14 and 15 coronal plates. At the ambitus on the abactinal side there
are 12 rows of primary tubercles which form disconnected vertical rows ; at the
tenth plate there are but five rows and at the third plate from the apex
only three. The tubercles diminish but slightly in size from the ambitus
towards the abactinal system and the intertubercular space is well filled with
miliaries. Below the ambitus on the actinal side are found the largest of
the primary tubercles forming two horizontal lines, the lower one of which is
the largest, extending across the fifth and sixth plates from the actinal sys-
tem. These tubercles carry the large flattened radioles truncated at the tip
which form the ring of larger radioles round the base of the abactinal part of
the test.

Between the row of large tubercles and the actinal system the interambu-
lacral plates on each side of the poriferous field become much narrower
(Pis. 41, fig. 1 ; 38, fig. 1 ; 34, fig. 1). There are only four indistinct verti-
cal rows of small primary tubercles. The rest of the plates is filled with
still smaller primary tubercles and patches of miliaries irregularly arranged.

The actinal lips are short but well marked. The lower part of fig. 1, PI. 41,
shows the distortion which takes place in the outline of the large primary
tubercles below the ambitus owing to the great compression due to the forma-
tion of the sharp angle of the test at the ambitus. Fig. 3, PI. 41, shows one
of the most distorted of the primary tubercles on the fifth plate from the
actinostome, the mammary boss, and the scrobicular area being pushed out of
shape. Fig. ^ shows the same tubercle in profile. Fig. 2, PI. 41, shows the
more regular primary tubercles of the abactinal part of the test in which
the boss and the scrobicular area are but slightly distorted, the boss and
area being usually circular, PI. 41, fig. 5. The grouping of the miliaries does
not seem to follow any rule. PI. 41, fig. 6, shows those of one of the plates
near the actinostome of the right posterior ambulacrum. U'vtyfev

In a specimen measuring 88 mm. in diameter, including the spines, it is pos- /

sible to trace the twelve vertical rows of the primary radioles of the interam-
bulacral areas. In PI. 39, fig. 3, the dotted lines show the twelve rows of the
right posterior interambulacrum and the four vertical rows of the right poste-

12 TROPICAL TACIFIC ECHINI.

rior ambulacrum. On fig. 4 of the same plate are shown the corresponding
vertical rows of the right anterior ambulacrum and interambulacrum. In
both the interambulacra two of the vertical rows along the median line are
included by the inner and outer rows and do not extend either to the abactinal
or the ambital region.

The abactinal system when denuded shows that the genital plates are
covered with closely packed primary tubercles only slightly smaller than those
of the rest of the abactinal surface of the test above the ambitus. (Pis. 34,
fig. S; 38, fig. 2; 43, fig. S.) There are in addition a few miliaries and small
secondaries irregularly scattered between the larger tubercles.

The madreporic genital is much larger than the other genitals ; the madre-
porite occupies the greater of the two sides of the plate. The proximal part
carries two primary tubercles and from four to five smaller ones as well as
a few miliaries. The genital openings are large, slightly sunken ; the lateral
posterior genitals are smaller than the odd posterior genital and the left ante-
rior ones. (PI. 43, fig. S.)

The genital plates are heptagonal. The left anterior genital carries no less
than sixteen primaries with a few miliaries and a couple of smaller primaries.
(PI. 41, fig. 7.) The other genitals carry from twelve to fourteen primaries
with a few miliaries and secondaries.

The ocular plates are pentagonal, they carry three primary tubercles with
two or three small miliaries, the ocular pores are very small. The posterior
oculars approach the anal system nearer than the anterior pair or the odd
ocular. (PI. 43, figs. S, 3.)

The anal system is irregularly circular and covered with three to four con-
centric rows of irregularly shaped pointed and elliptical plates. (PL 43, figs.
2,3.)

In a specimen of Colob. Mertmm. measuring 88 mm., when seen from
above the primary radioles covering the abactinal system are seen to be some-
what smaller than those of the rest of the test (Pis. 33, fig. 2; 37, fig. 2; 43,
fig. 1), with the exception of a few larger triangular and elliptical ones which
bridge over the anal system (Pis. 40, figs. 30-32; 43, fig. l).

On Plates 33 and 37 are given views of a specimen of Colob. Mertmsii,'zAZ^/^^y^
measuring 88 mm. in diameter. The ambital fringe of large truncated flat- j

tened primary spines carried by the larger tubercles on the actinal side of
the ambitus and at the ambitus resemble slightly those of Podophom atrata ;
they are comparatively shorter and narrower (Pis. 33, figs. 1, 2; 37, figs. 1, 2)

THE GENUS COLOBOCENTEOTUS. 13

than those of that species (Pis. -9^, figs. J.-5; ^, figs. 1-3). The primaries of

A A A

the abactinal side of the test are much smaller than those of Podophora
and are loosely packed upon the test, leaving considerable open space round
each tubercle. This open space is specially marked on the line separating the
ambulacral from the interambulacral zones (Pis. 33, figs. 2, 3; 37, figs. 2, 3).
The general color* of the radioles is of a grayish pink color with a slight
tinge of green on the upper surface of the larger primary ambital radioles.

Seen in profile and from the abactinal side the primary radioles which are
irregularly circular at the tip are seen to diminish very gradually in size above
the ambitus as they reach towards the apical system (Pis. 33, figs. 2, 3; 37,
figs. 2, S). The large abactinal radioles immediately above the ambitus are
arranged more closely than those more distant from it (Pis. 33, fig. 3; 37,
fig. 3).

Seen from the actinal side (Pis. 33, fig. 1; 37, fig. 1), the actinal membrane
is nearly bare, carrying but few small clusters of miliary spines on the pairs
of poriferous plates and a few minute spines irregularly scattered over it.
(Pis. 33, fig. 1; 37, fig. 1). The actinal side of the test below the ambitus is
covered with slender somewhat club-shaped spines varying but slightly in
shape or size between the actinal system and the actinal side of the ambitus.
The poriferous fields are separated by wide interambulacral zones (Pis. 33,
fig. I; 37, fig. I).

The spines of the actinal system close to the teeth are short, club-shaped,
slightly flattened (PL 40, fig. 1) ; those from the buccal membrane are some-
what longer (PI. 40, fig. 2). Half way between the actinal system and the
ambitus the radioles are much stouter and only slightly club-shaped (PI. 40,
figs. 3, Jf), as are the smaller spines found on the smaller secondary granules
or larger miliaries (PI. 40, fig. 5) ; these spines are all delicately striated with
an ill-defined milled ring.

Below the ambitus we pass suddenly to much larger flattened, angular
radioles, rounded at the tip, with a large base for the muscular attachment
(PI. 40, figs. 6-8). These spines form a part of the principal subambital
fringe of radioles^ the primary radioles of which are figured on PI. 40,
figs. 9-11 ; these radioles resemble those of P. jyedifera, but are comparatively
shorter and narrower ; they are flat on the lower surface, somewhat spathi-
form on the upper surface, and greatly flattened towards the tip of the
radiole, as is shown by a profile view (PI. 40, figs. 9, 11).

We now come to the larger spines of the abactinal pavement immediately

14 TROPICAL PACIFIC ECHINI.

above the ambitus ; they are highly asymmetric, fan-shaped, and polygonal
(PI. 40, figs. 12~lJi) ; somewhat more abactinally from the ambitus the polyg-
onal radioles are smaller (PI. 40, figs. 15-17) ; midway between the ambitus and
the abactinal system the primary radioles of the odd ambulacrum are slightly
smaller than those nearer the ambitus (compare PI. 40, figs. 18-20, to PI. 40,
figs. 21-23) ; nearer the abactinal system the radioles have become still
smaller (PL 40, figs. 2Jt, 25; and PI. 40, figs. 26, 27). PI. 40, fig. 28, is
one of the miliary spines from the upper extremity of the right posterior
interambulacrum, hidden by the larger primary radioles. Figures of
some of the primary radioles of the anal system are given on PI. 40, figs.
29-32.

Seen from the interior, there is a small triangular plate_between the actinal
plates of the odd posterior interambulacrurc/(Pl. 43, fig.£^and of the right (oi t^j
anterior interambulacruiYj which may be the remnant of the primordial plates
of these interambulacra.

PoDOpnoRA Agass.

Podophora atrata Agass.

Pis. 2, figs. 1-3; 3% figs. 5-8; 16, figs.9-i.i; 17-28; 31, figs. 5-5.

A fine specimen of Podopliora atrata, measuring 97 mm. including the
spines, is figured on PI. 21''. It was collected, with others, by the Hon.
Nicolas Pike, at Mauritius. When seen from above, it is of a dark violet,
almost black ; seen from the actinal side the marginal spines are of a light
violet color towards the tip, passing to a very light shade of the same color.
The smaller flattened and elongated actinal spines, as well as the miliary spines
of the buccal plates, are of the latter shade ; the actinal membrane is chocolate
bi'own. The larger marginal spines are of a somewhat lighter color on the
upper side, with a tinge of green ; the upper surface is also coarsely and
irregularly granular and pitted. On the lower side they are smooth or only
slightly pitted near the tip.

A very interesting specimen of Podophora atrata from Mauritius is figured
on Plate 21", figs. 1-3. It is marked for the abnormal development of a number
of the ambital radioles. Instead of being merely cylindrical as is the case in
the large majority of the specimens examined they are club-shaped and pro-
portionally larger than the ambital radioles usually are. Their shape reminds
one somewhat of the club-shaped spines of Ciduris Bliimcnhachii

THE GENUS COLOBOCENTEOTUS. 15

The actinal system of PodojjJiora atrata is pentagonal (Pis. 20, fig. Z;
21, fig. l). The lips of the gill cuts are short, sharply marked; the proportion
of the actinostome to the test is as 23 to SS. There are five pairs of small
rectangular poriferous plates. The buccal membrane is only covered by a few
round or elliptical plates irregularly scattered and with five clusters of narrow
crescent-shaped plates placed distally next to the pairs of poriferous plates.

In a smaller specimen (PI. 25, fig. 2) the poriferous buccal plates form a
nearly closed ring, the elongated buccal plates are less closely packed than in
older specimens, and the isolated circular plates are more distant.

The changes which take place in the interambulacral zones during the
growth of the test are shown on PI. 24, figs. l-J^, giving the left anterior
interambulacrum of specimens measuring 8, 14, 26, and 45 mm. in diameter.
In fig. 1, the same as PI. 25, figs. 1-5, there are six and seven interambulacral
plates, each carrying a large or small primai'y tubercle, with a number of
miliaries or small secondaries along the median line and the outer edge of
the plates.

On PI. 24, fig. 2, a specimen measuring 14 mm. in diameter, there are
eight and nine interambulacral plates, and a second vertical row of primary
tubercles is forming along the median line of the fourth and fifth plates, as
well as another vertical row of small secondaries on the outer edges of the
third, fourth, fifth, sixth, and the second, third, fourth, fifth plates counting
from the actinostome.

On PI. 24, fig. 1, these two outer vertical and median rows can be detected
by the greater size of the small secondary on each side of the two primary
rows in the position of the new vertical rows well developed in fig. 2. In
the next stage of the same interambulacrum figured, a specimen measuring
26 mm. in diameter (PI. 24, fig. 3) with eleven and eleven plates, the four
vertical rows of primary tubercles are well developed. The first rows, so
prominent in figs. 1, 2, are still readily distinguished from the two inner
and the two outer rows by the greater size of the primary tubercles, which
extend from the second to the seventh plate, while the two inner rows extend
the one from the fourth to the eighth plate, the other from the fifth to the
eighth plate.

In the specimen, figured on PI. 24, fig. 2, the miliaries are proportion-
ally much more numerous than in the younger specimen (PI. 24, fig. 1) ; they
are quite crowded in the next stage (PI. 24, fig. 5), and in the older specimen,
45 mm. in diameter, they are somewhat more openly arranged (PI. 24, fig. 4).

16 TROPICAL PACIFIC ECHINI.

In this specimen there are twelve and twelve plates; the outer vertical rows
extend from the second to the ninth and perhaps to the tenth plate, the inner
median rows from the fourth to the ninth plate. There still exists a marked
difference in the size of the primaries of the first vertical rows near and at the
ambitus compared to the primary tubercles of the other rows, which, with the
exception of the upper tubercles, are neai'ly of the same size. It will be
noticed that the outline of the scrobicular areas and of the mammary boss
varies greatly; they are circular, angular, or elliptical according to their posi-
tion in the plate and the amount of space available (see PL 24, figs. 5,
7, 8). These changes are due to the great pressure brought about, especially
at the ambitus, by the sudden change of direction in the plates passing from
the abactinal side to the ambitus and to the actinal surface. It will be seen
that in the large specimen (PI. 24, fig. 4) there are on the actinal side four
vertical rows of small secondary tubercles separating the adjoining interam-
bulacral rows (PI. 24, fig. 4)-

The order of appearance of the tubercles of the vertical rows can be
equally well traced in specimens covered with radioles. On PI. 25, fig. 1, is
seen a young specimen 14 mm. in diameter with the spines having but
two vertical rows of large primary tubercles, as in PI. 24, fig. 1, and PI. 25,
figs. 3, 4. PL 25, fig. 1, shows the pavement of i-adioles of the five ambula-
cral and interambulacral zones, each with two rows of primary radioles and
the pavement covering the abactinal system. This is shown more in de-
tail on PI. 22, fig. 1. In fig. 2 of the same plate, in a somewhat larger
individual, we can see the first trace of the spines of the inner vertical row
of tubercles. This is somewhat more advanced in the next largest speci-
men figured, PL 22, fig. 3. In a specimen of 26 mm. the small radioles of
two of the plates of the outer rows can be distinguished; those of the inner
median rows are well seen. In the next stage these radioles have all become
larger and more prominent (PL 22, fig. 4)- In the following stages, from
specimens measuring 31 mm. to 77 mm. in diameter, the mode of appearance
of the radioles becomes more and more apparent and the vertical lines of
primary tubercles more distinct (PL 22, figs. 5-10). In PL 22, figs. 5-7, the
distinctness of the outer vertical zones and of the inner median zones becomes
clearer with increasing size, and in the specimens of PL 22, figs. 8-10, of 67 to
77 mm. in diameter, the dotted lines on the radioles show the course of the
primary vertical row with the dotted lines marking the position of the lateral
and median vertical lines.

THE GENUS COLOBOCENTROTUS. 17

The denuded test of PI. 24, fig. 4, corresponds nearly to that of PI. 22, fig.
10, covered with spines ; that of PI. 22, fig. 6, to a stage intermediate between
PI. 24, figs. 2 and 3.

In a small specimen of Podophora atraia the actinal plates of the odd inter-
ambulacral zone did not show any trace of the primordial plate (PL 26, fig. ii).

The passage of the regular poriferous arcs into the laterally expanded porif-
erous field on the actinal side of a specimen 45 mm. in diameter is shown on
PL 25, fig. 10, where the upper plate is on the abactinal surface and the lower
plate on the actinal side of the test, the former having an arc of nine porifer-
ous plates, the other of eleven pairs of pores arranged diagonally across the
outer part of the plate, which is considerably larger than the plate above it
(PL 25, fig. 10). The lower poriferous pair is pushed towards the median
ambulacral line.

In a younger specimen of 8 mm. in diameter (PL 25, fig. 7), taking the same
plates of the odd ambulacral zone partly on the actinal side and partly above
the ambitus, we find on the abactinal side the same arc of nine poriferous plates
arranged round the base of the primary ambulacral tubercle, and on the
actinal side thirteen pairs of pores arranged diagonally across the outer side
of the more elongated actinal ambulacral plates preceding it.

The arrangement of the arcs of poriferous plates on the abactinal side of
the test is seen on Pis. 20, figs, l^, 6; 21, figs. £, 3; 25, figs. 3, 4., 5, and the
subsequently developed actinal poriferous field on Pis. 20, fig. 2; 21, fig. 1;
25, figs. 2, 6, 9. There are many miliaries in the poriferous field (PL 25,
fig. 9) in marked contrast to their absence in P. pedifera.

A figure of P. atrata from the actmal side showing the arrangement of the
poriferous field has been given by Loven, (Etudes PL XVIII, fig. 158).

The arrangement of the abactinal part of the ambulacral system of Podo-
phora atrata is somewhat different from that of P. pedifera. The youngest
plate is at once followed by a plate cut in two by an upper poriferous plate
extending across the ambulacral plate and followed by nine poriferous demi-
plates ; these extend from the edge of the interambulacral zone half way to the
median ambulacral line (see PL 26, figs. 15, 16).

In an interior view of the abactinal part of the test (PL 25, fig. 5) the ar-
rangement and number of the ambulacral plates are clearly drawn and the
succession of the large and small ambulacral plates well indicated. In a part
of the odd anterior ambulacrum of a larger specimen, 45 mm. in diameter,
we can follow close to the ambitus the beginning of the widening of the

18 TROPICAL PACIFIC ECHINI.

ambulacral plates and the flattening of the smaller intercalated plate (PL 26,
fig. H). In Podophora atrata there are larger miliaries than in P. pedifera
along the median ambulacral line (PI. 21, fig. 3).

In P. atrata the pavement of radioles covering the abactinal system is made
np of more irregularly shaped radioles than in. P. jndifera (PI. 26, figs. 2, ^).
Both the genital and ocular plates are more elongate than those of P. pedi-
fera, and the genital plates carry from two to four small secondaries with a
few small miliaries irregularly scattered. The ocular plates, as in P . pedifera,
also carry one small secondary tubercle, with five to ten small miliaries (PI.
26, fig. 3). In all the species both of Colobocentrotus and Podophora the
ocular plates of the bivium are nearer the anal system than those of the
trivium. The right anterior genital plate is nearly covered" by the madrepo-
rite, and carries a few small secondaries along the median line with two or
three clusters of miliaries.

In a smaller specimen (PI. 25, fig. 3) there are few miliaries on the abac-
tinal system (PI. 26, fig. i), with three to four secondary tubercles of uniform
size on the genitals, and few miliaries. Seen from the interior (PI. 25, fig. 5)
the sutures of the abactinal system are well shown. The madreporite is a
narrow band extending across the anterior extremity of the right anterior
genital (Pis. 26, fig. 1; 25, fig. 3).

The genital pores are proportionally smaller in P. atrata (Pi. 26, fig. 3)
than in P. pedifera, and are placed as in that species at the very tip of the
genital plates. In the young specimen (PI. 26, fig. i) there is as yet no trace
of genital pores, but the ocular pores are well developed.

PI. 26, fig. 5 shows the anal system of a specimen measuring 8 mm. in
diameter (PI. 26, fig. i), with eight plates covering the whole anal system.
In a somewhat larger specimen the number of plates has increased, and they
are not as regularly arranged. In a still larger specimen there are two rows
of plates, the outer one being composed of large triangular ones (PI. 26, fig. 7),
and in a specimen of 45 mm. in diameter (PI. 26, fig. 8) we have a magnified
view of the anal plates of PI. 26, fig. 3.

The principal types of radioles of Podophora atrata are represented on PI. 23.

Fig. i is a small spine from the actinal membrane near tlie teeth.

Figs. 2-5 are from the odd ambulacrum and the left anterior interambula-
crum near the actinal system.

Figs. 6-8 are views of a slightly flattened primary radiole from the left
posterior interambulacrum from the actinal side of the ambitus.

THE GENUS COLOBOCENTROTUS. 19

Figs. 9-11 are drawings of the characteristic stout elliptical radioles of
P. atrata, rounded or slightly pointed at the extremity, taken from the
ambitus where they form a ring at the base of the pavement of polygonal
radioles extending from the abactinal side of the ambitus to the apex. The
ambital radioles are from 15 to 20 mm. in length, and of a dark violet color,
almost black on the upper side ; on the actinal side the color of the spines
is yellowish or light brown. These large radioles are finely striated, of a
dark violet, with a well-marked milled ring. Blamville writes " d'un violet
fonq^ presque noir."

Figs. 12-U are views of short triangular radioles from the ambitus which
form a part of the abactinal polygonal pavement of the test ; they are taken
from the left posterior interambulacrum.

Figs. 15-17, views of a somewhat mushroom-shaped hexagonal or polygonal
radiole taken from the abactinal side of the ambitus, from the right posterior
ambulacrum.

Figs. 18-20 and figs. 21-23 are polygonal radioles taken from the right
anterior interambulacrum from the abactinal side of the ambitus ; and figs.
24, 25 is a similar radiole taken from the right posterior interambulacrum.

Figs. 26-28, drawings of a low mushroom-shaped asymmetrical polygonal
radiole taken from half way between the ambitus and the abactinal system.

Figs. 29-31 is an irregularly hexagonal radiole taken from the genital
plates ; fig. 32 is a radiole taken from the madreporic genital ; and fig. S3
represents a miliary spine hidden by the large pavement of abactinal primary
radioles.

It will be seen on examining the figures of radioles given on Plate 23 that,
with the exception of the spines of the actinal side and of the miliary spines,
all the radioles are asymmetrical.

The striking difference between the radioles of Podophora pedifera and
those of Podophora atrata is well shown on comparing PI. 11, figs. 11-13;
U-16; 17, 18; 20-21; 22-21t; 25-27; 28-30; 31-33 with. Plate 23, figs./-5; 9- ^i
11; 12-lk; 15-17 ; 18-20; 21-23; 26-28; 29-31. The most marked differences /
are in those of the ambital radioles (compare PI. 11, figs. 11-13 with PI. 23,
figs. 9-11).

Podophora pedifera Agass.
Plates 1; 3% figs. 1-4; 4-16, figs. 1-8; 31, figs. 1-i.

This species was figured in the Revision of the Echini (PI. IIF, fig. S),
under the name of Colobocentrotus atratus, and noted as having been collected

20 TEOPICAL PACIFIC ECHINI.

at Callao. A number of specimens were collected by the " Albatross " at
Fakarava on the sea-face of the reef,- during the Tropical Pacific Expedition,
1899-1900. An alcoholic specimen in the Museum collection is labelled
Valparaiso ? It would seem, therefore, that Podojyhora pedifera is character-
istic of the Eastern Pacific, extending from Peru and Chili as far as the
Western Paumotus, while the typical Podojihora atrata, figured by Blainville,
extends from the Hawaiian Islands to Mauritius, the Seychelles, and Zanzibar.

Seen from above the color of the test is olive green, darkest near the
abactinal system, the pavement of radioles near the ambitus becoming lighter
in color with a purplish tint ; the large marginal spines are greenish with an
occasional tinge of purple. Seen from the actinal side the color of the margi-
nal and flattened elongated actinal spines is of a dirty yellow color, the large
marginal radioles being of a light brownish pink at the tip. The actinal
membrane is dark brown.

Podophora pedifera and Podophora atrata are readily distinguished. The
row of primary, flat, truncated radioles which forms a close ring round the
test at the ambitus in P. pedifera (Pis. 7, figs. 1-3 ; 9, figs. J^-6) is in striking
contrast to the corresponding ring of radioles in P. atrata, which consists
of flattened elliptical radioles rounded at the tip and well separated one from
the other (PI. 20, figs. 1, 3, 5). A comparison of the corresponding figures
of Plates 7, 9, and Plates 20, 21% 21'', shows this contrast at once. The
abactinal radioles of P. pedifera above the ambitus form a close pavement of
irregularly shaped low radioles closely fitting together, of a prevailing hexagonal
outline, while the corresponding pavement of the low radioles of P. atrata
consists of radioles of a rather rhomboidal or pentagonal outline and less
frequently hexagonal (compare Pis. 20, tigs. 3, 5 ; 21, figs. J^~6 with Pis. 7,
figs. 2,3; 9, figs. 5, 6). The outline of the test is higher, more arched in
P. pedifera (Pis. 7, fig. 3; 8, fig. 3; 9, figs. 3, 6) than in P. atrata, which is
flatter and slightly conical (Pis. 20, figs. 5, 6; 21, figs. 3, 6). P. atrata is very
much flatter on the actinal side (Pis. 20, figs. 1, 2, 6; 21, figs. 1, 3, 4) than
P. pedifera in which the actinostome is somewhat sunken (Pis. 8, figs. 1, 3; 9,
figs. 1, 3, Jt). The ambulacral poriferous zone is also proportionally much wider
in P. pedifera (Pis. 8, fig. 1; 9, fig. l) than in P. atrata (Pis. 20, fig. 2; 21,
fig. 1) where the median rows of tubercles of the ambulacral zone extend far
towards the actinostome (Pis. 20, fig. 2; 21, fig. i), while in P. pedifera the
corresponding ambulacral tubercles extend but little beyond the ambitus
(Pis. 8, fig. 1; 9, fig. i). The actinal interambulacral zone is also much broader

THE GENUS COLOBOCENTROTUS. 21

in P.atrata (Pis. 20, fig 2; 21, fig. i), while it is quite narrow in P. pedifera
(Pis. 8, fig. 1; 9, fig. l). In the latter there are two rows of small primary
tubercles, while there are four in the former.

Figures ^ of Plates 9 and 21 show how large an area of the actinal surface is
occupied by the closely packed ambulacral suckers, and we can judge of the great
power exerted by these numerous suckers in keeping hold of the rock to which
they are attached even when exposed to the full action of the surf on the outer
beach of a coral reef. The sea has practically no hold on the pavement of
radicles which covers the abactinal side of the test, and thus with the ambu-
lacral suckers a cup is formed which it is difficult to detach from the rocks.

The large and small primary tubercles of P. pedifera are comparatively
larger than those of P. atrata ; the former occupy nearly the whole of the inter-
ambulacral and ambulacral plates leaving but little space for the smaller
secondaries and miliaries, while in P. atrata the tubercles leave quite a part of
the plate bare which carries a few miliaries and small secondary tubercles, and
is covered by an indistinct granulation. In both these species the tubercles
are most prominent, very glossy as if they were rounded beads made of wax
(Pis. 8, 20, figs. 4, 6).

The tubercles diminish somewhat in size from the ambitus towards the
abactinal system (Pis. 8, fig. 3; 9, fig. 3; 20, fig. 6; 21, fig. 3) which is covered
by small secondary tubercles, with the exception of the anal system ; but even
that is completely hidden by the pavement of secondary radioles on the geni-
tal plates which lap over the anal system and conceal it (Pis. 7, fig. 2; 20,
fig. 3, and Pis. 9, fig. 5; 21, fig. 5). The genitals carry a few miliaries.
In both these species the anal system is covered with two or three irregularly
concentric rows of small triangular plates (Pis. 9, fig. 2; 21, fig. 2). Accord-
ing to the size of the specimens there are in P. pedifera from six to eight large
tubercles at the ambitus in the interambulacral areas forming six to eight
vertical rows, of which only two extend to the actinal system. There are
but two vertical rows of primary tubercles in the ambulacral zones (PI. 9,
fig. 3), with a few small miliaries along the median line. Towards the ab-
actinal system a few small secondary tubercles occupy a part of the outer
edges of the interambulacral plates. On the actinal side towards the actino-
stome the primary tubercles of the ambitus are soon replaced by small
secondaries both in the ambulacral and interambulacral areas (Pis. 8, figs.
1, 3; 9, figs. 1, 3; 20, fig. 2; 21, fig. l).

A comparison of the left anterior interambulacrum of a denuded specimen

22 TROPICAL PACIFIC ECHINI.

of Podophora pedifera measuring 55 mm. in diameter (PI. 12, fig. 1) with the
same interambiilacrum of Podopliora atrata of a somewhat smaller specimen
(PI. 24, fig. 4) will show at once the great difierence there is in the tuberculation
of the two species of the genus Podophora. Their development results in the
one case (P, pedifera) in a specimen of twelve and thirteen plates to four
vertical rows, and in the other {P. atrata) to three vertical rows on each inter-
ambulacral plate in a specimen of twelve and twelve interambulacral plates.
The narrowness of the actinal part of the interambulacral zone is very marked
as contrasted to P. atrata (PI. 12, fig. i), as well as the extension of the lip of
the gill slits to the fourth plate from the actinostome separating the two outer
vertical zones from the inner ones. The difference in outline of the scrobic-
ular areas and the mammary boss of this species (PI. 12, figs. 2-6) is as marked
as in P. atrata. There are fewer miliaries than in P. atrata, owing to the
comparatively larger size of the primary tubercles which leave less space
between the scrobicular areas of the primary tubercles for their development.

I have given figures on Plate 10 showing the order of development of the
primary tubercles of some large specimens of P. pedifera measuring from 76
to 87 mm. in diameter (PI. 10, figs. 1-6). We can trace in all the figures the
radioles belonging to the two outer vertical rows, those of the primary row,
and those adjacent to the median line. As will be seen on examining the
figures, the position of the radioles shows the greatest regularity in the growth
of the eight vertical rows of the interambulacral system of P. pedifera just as
they did in the growth of the six vertical rows of the interambulacral zone of
P. atrata. Seen from the mterior of the test the plates of the right antei'ior
interambulacra adjoining the actinal system show what seems to be the ir-
regular remnant of the primordial plate (PI. 14, fig. 8). Such a plate does
not exist in the odd posterior interambulacrum (PI. 14, fig. 9).

In a section of P. pedifera (PI. 13, fig. 1) the outline of the test at the
ambitus is seen to be pentagonal, the point of the pentagon running across
the median line of the odd posterior interambulacrum. The pentagon of the
actinal system runs in the opposite direction. The gradual narrowing up of
the interambulacral plates at the ambitus is shown from the same figure, as
well as the tufts of miliary spines rising at the base of flattened primary spines
in both the ambulacral and interambulacral areas.

The abactinal part of the ambulacral system consists of simple pairs of
pores, the secondary plates of which extend about two thirds across the pri-
mary plates (PI. 13, fig. 8). The second plate has eight pairs of pores, the upper

THE GENUS COLOBOCENTROTUS. 23

plate only six ; the ambulacral plates are much cut up, there being seven plates
and demi-plates in the length of two plates.

The poriferous arcs extend down to a little above the ambitus (Pis. 8,
figs. 2, 3; 9, figs. 2, 3), where the regular arrangement of the pores begins
to be disturbed and they become crowded laterally, see Pis. 8, fig. 1; 9,
figs. 2, 3. Below the ambitus on the actinal side the pairs of pores are thrown
aside laterally and greatly crowded (PI. 1.3, figs. 3, 4), as is shown in PI. 13,
fig. 3, on the actinal side, and PI. 13, fig. 4, from the interior of the same
plates. There are but few miliaries in the poriferous field (PI. 13, fig. 3). The
passage of the regular arcs into the broad poriferous field is well shown for
P. atrata on PI. 25, figs. 6^10. The apical system and the arrangement of j"7, 9,
the pores of the abactinal part of the ambulacral system of a large speci- ^
men measuring 82 mm. is seen on PI. 14, fig. 4. In the second plate from the
apex the upper demi-plate is followed by a row of seven poriferous plates which
extend across the plate towards the median line, and beyond the projection
of the large plate and its last pair of pores. When we come to the fifth
ambulacral plate, counting from the actinal system, there are eleven pairs of
pores arranged in a huge arc round the base of the primary tubercle. The
upper pair is pushed out laterally well toward the median line (PI. 13, fig. 6).
The corresponding ambulacral plates seen from the interior (PI. 13, fig. 7) are
seen to be made up of a large plate and a narrow, elongated, and smaller plate,
the large plate having nine intercalated poriferous demi-plates extending about
two thirds across it from the side of the interambulacrum ; the small plate
having two intercalated poriferous plates. The inner line of sutures of the
intercalated poriferous plates forms a slightly zigzag-shaped vertical line
more or less parallel to the median ambulacral line.

In P. indifera the actinal system is proportionally larger (Pis. 8,
fig. 1; 9, fig. J) than in P. atrata. The ratio of the actinostome to the test
is as 28 to 46. The pairs of poriferous actinal plates are elliptical and larger
than in P. atrata; they are more distant from the teeth and are fairly covered
with secondaries and miliaries. The buccal membrane is nearly covered with a
belt of crescent-shaped plates somewhat more closely packed distally from
the five pairs of poriferous plates (PI. 13, fig. 2). Between the teeth and
the buccal poriferous plates there is a ring of small elliptical plates (Pis. 7,
fig. i;8, fig. i; 9, figs. 1,4; 13, fig. ^).

The thin folds of the actinal cuts extend almost to the ambitus, enclos-
ing in a sort of furrow the two rows of small secondary interambulacral

24 TROPICAL PACIFIC ECHINI.

tubercles which extend to the actinostome (Pis. 8, fig. 1; 9, fig. 1; 12,
fig.i).

In the abactinal system of P. pedifera the genital plates (PI. 14,
fig. 3) carry from two to three large secondary tubercles with one to three
very small secondaries or miliaries in the angles of the plates adjoining the
anal system . The genital plates are irregularly heptagonal, the anterior plates
elongate, the posterior broader than long. The ocular plates are pentagonal
with a broad base curved towards the ambulacral system. They carry one
large secondary tubercle, sometimes also a couple of miliaries, and have a
well-marked ocular pore.

The madreporic genital is elongate, carries three large secondary tubercles,
one in the centre of the plate, the others near the anal system, with five to
six small secondaries. The madreporite occupies the greater part of the geni-
tal. Seen from above, covered with radioles, the abactinal system (PI. 14,
fig. J) forms a close pavement of irregular pentagonal plates which completely
hide the anal system.

The genital pores are large. They occupy the distal points of the genital
plates. They are well seen on PI. 14, fig. Jf, an interior view of the abactinal
system. This figure also shows the simple arrangement of the abactinal
pairs of pores above the few intercalated demi-plates. The anal system is cir-
cular, covered with three to four rows of small, irregular, elliptical plates.

There is a great contrast between the genital plates of P. pedifera (PL 14,
fig. 3) with its three large secondary tubercles closely wedged together, and the
genital plates of P. atrata with its four distant, large secondary tubercles
(Pis. 25, fig. 8; 26, figs. 1,3).

On Plate 11 has been figured a series of spines of a specimen measuring
82 mm. in diameter selected to represent the great difference and varia-
tion among the primary radioles of the ambital and abactinal part of the test
as well as of the spines of the actinal region and of the miliary spines
hidden by the pavement of primary radioles of the abactinal system (Pis. 11,
fig. 1; 46-48). Figure 1 also shows the great development of the power-
ful muscular system which holds the radioles in place upon their corresponding
primary tubercles. Figures 2-10 of Plate 11 show the shape of the radioles of
the plates of the buccal membrane of the actinal system and of the first plates
of the odd anterior ambulacrum and anterior interambulacrum. These radioles
are all finely striated, somewhat club-shaped, slightly flattened towards the tip,
with an indistinct milled ring and a deep socket at the base of the radioles.

THE GENUS COLOBOCENTROTUS. 25

The ambulacral radicles near the ambitus (PL 11, figs. 9, 10), are the first
to show a marked flattening and to approach in outline the large,
flattened, spatula-shaped radioles of the ambital region (PL 11, figs. 11-13,
14-16). The principal and most characteristic row of primary radioles
(PL 11, figs. 11-13) is at the ambitus and it is the one which with the pave-
ment of abactinal primary radioles gives to Colobocentrotus and Podophora
their striking characteristics. These ambital radioles vary in length from
15 to 18 mm.; they are olive-green in color.

It is interesting to follow the gradual changes which take place in the
ambital radioles (PL 11, figs 11-13) as they are succeeded by the more
abactinal radioles (PL 11, figs. 14-16) and gradually form more pavement-
like, hexagonal, somewhat shorter radioles (PL 11, figs. 17, 18), to be followed
by still shorter radioles (PL 11, figs. 19-21), and then the irregular, short,
mushroom-shaped polygonal or hexagonal radioles (PL 11, figs. 22-24; 25-27 ;
28-30; 31-33), on the thirteenth plate counting from the actinostome.- A
series of small, mushroom-shaped radioles has also been selected from the
ocular and genital plates. They continue the abactinal pavement over the
abactinal system (PL 11, figs. 34-36; 37-39; 40, 41; 43, 43; 44, 45). The color
of the primary radioles is olive green. It will be observed that with the
exception of the radioles of the actinal side and of the miliary spines all
the radioles are asymmetrical.

The Lanterns and Auricles of Colobocentrotus and Podophora.

Plates 13, figs. 1-4; 14, figs. 5-7; 15; 26, figs. 9-13; 27; 28;
42, figs. lU; 43, figs. 4, 5; 44.

The differences in the various parts of the lanterns of Podophora pedifera
and P. atrata are very marked ; they are seen in the shape of the compass
(Pis. 15, figs. 13a b ; 27, figs. 14 a h; 28, figs. 11 a b), in the proportions of the
corrugations of the sides of the pyramid (Pis. 15, figs. 4, 5, 8, 9 a b ; 27,
figs. 4, 5, 7, 8 b ; 28, figs. 4, 5, 7 b, 8 b) ; they are much coarser and less
numerous in young specimens (see PL 27, figs. 4, 5, 7, 8). The foramen of
the pyramids is longer in P. pedifera than in P. atrata (Pis. 15, figs. 2, 3;
27, 2, 3; 28, figs. 2, 3). The foramen formed by the apophyses and their
hooklike appendages (PL 15, figs. 3, 4) is much larger than in young specimens
of P. atrata (PL 27, figs. 5, 4), where it is rectangular ; there are no hooks to
the apophyses (PL 27, figs. 7, 8 a) while they are well developed in older speci-

26 TROPICAL PACIFIC ECHINI.

mens (PI. 28, figs. 3, ^,7 a, 8 a) but do not compare in length with those of
P. pedifera (PL 15, figs. 3, 4, 7 a, 9 a). The compass is distinctly jointed
in P. pedifera and in the young of P. atrata (Pis. 15, fig. 13 ; 27, fig. U) ; in
the old of atrata there is no trace of any suture. The differences in the braces
are very slight.

In Colobocentrotiis Stimp)Soni, the pyramids are broader at the summit (PI.
44, figs. 3, 4) than the pyramids of the other species ; the corrugations are
coarser (PI. 44, figs. 4, 5, 8 a, 9) ; the apophysal foramen is wider than that of
P. pedifera, and the hooks are intermediate in length between those of P. j^e-
difera and P. atrata. The compass is jointed (PI. 44, figs. 12 a, b).

The auricles of a small specimen of P. atrata, 8 mm. in diameter, are not
united (PL 26, figs. 9, 10) ; they touch in a specimen of 14 mm. (PL 26,
fig. 12) and are connected in a specimen of 45 mm. (PL 26, fig. 13). In a
large specimen of P. j^edifera 82 mm. in diameter they are closely connected
(PL 14, figs. 5, 6); the same is the case in a specimen of Colohocentrotus
Sti^npsoni of 88 mm. in diameter (PL 43, figs. 4, 5).

The pores close to the actinal system show how the ambulacral plates grad-
ually increase in number and become resorbed as they move into the base of
the auricles both from the actinal and the abactinal sides (see Pis. 14, figs. 5,
6; 26, figs. 12, 13; 43, figs. 4, 5; compare also PL 26, fig. 9 with PL 26, figs. 12,
13). The youngest poriferous plates are still seen on PL 14, fig. 6, and PL 43,
fig. 4; somewhat older plates are shown on PL 14, fig. 7, which have been
resorbed by the auricle (Pis. 14, fig. 5; 26, fig. 13); the upper part of the
auricle in fig. 7, PL 14, is cut off.

TuE Spicules of the Pedicels of Colobocentrotus and Podophora.

Pis. 16 ; 45.

A large number of pedicels of Colobocentrotus and Podophora have been
examined (Pis. 16, 45). They all agreed in having a disk made up of four
basal plates ; the periphery of the plates is angularly lobed. The number of
lobes varies from seven to thirteen. In Colohocentrotus Stimpsoni (PL 45,
figs. 1, 2) the plates have from twelve to thirteen lobes, while in the other
species of the genus, Colob. Mertensii, the basal disks have usually not more
than seven to nine lobes. See the figures of the disk of an actinal pedicel
of P. pedifera (PL 16, figs. 1-7), of P. atrata (PL 16, figs. 9-11, 13) and of
Coloh. Mertensii (PI. 45, fig. 7). At the base of the basal disk on the lower

THE GENUS COLOBOCENTROTUS. 27

side is found a set of three or four layers of yoke-shaped spicules (Pis. 16, fig.
6; 45, fig. 8). In P. jJedifera the yoke-shaped spicules are nearly straight
(Pi. 16, fig. 8), with a row of small perforations on the under side of the
spicule. In P. atrata the yoke-shaped spicule is well arched (PL 16, fig. 12)
with but few larger perforations.

These perforations frequently pass into more or less prominent teeth (PI.
45, figs. ^ 6). The yoke-shaped spicules of Coloh. Stimjjsoni (PI. 45, figs.
3-6) and Mertensii (PL 45, figs. 8, 9) have fewer perforations than those of
P. pedifera, but more than those of P. atrata. The position of the layers
of the yoke-shaped spicules with reference to the basal disks is well seen in
PL 16, figs. 6, 9, 10, and PL 45, fig. 8. Fig. U, PL 16, and fig. 10, PL 45,
show the atrophied tip of an abactinal pedicel. No spicules were found in
the tubes of the pedicels.

The changes due to growth in the appearance of the basal disk are shown
in figs. 11 and 13, PL 16 ; the former is the basal plate of the pedicel of a de-
nuded specimen of P. atrata measuring 8 mm. in diameter, the other of a
pedicel from a specimen measuring ,45'mm. with spines. -y A

The basal disks of the other species were taken from specimens varying /

between 70 and 88 mm. in diameter including the spines ; P. pedifera, 82 mm. ;
Colob. Mertensii, 70 mm. ; Coloh. Stimpsoni, 88 mm.

The Pedicellari^ of Colobocentrotus and Podophora.
Plates 3" ; 4-6 ; 17-19 ; 29 ; 30.

The four kinds of pedicellariae of Podophora joedifera are figured on
PL 3% figs. 1-4. The rods vary but little in length, but the length of the
necks differs greatly. In the tridentate pedicellarige (PL 3% fig. 1) the neck
is nearly twice as long as the rod ; in the ophicephalous pedicellariae (PL 3^,
fig. 2) it is but slightly longer than the rod.

The heads of the triphyllous and globiferous pedicellariae are small (PL 3%
figs. 3, 4), that of the triphyllous pedicellarise being scarcely wider than the
neck ; this is about twice the length of the rod (PL 3% fig. 3), while the neck
of the globiferous pedicellarige is reduced to a minimum, the valves seeming
to rest upon the head of the rod (PL 3'', fig. .4)-

The heads of the tridentate pedicellariae of Podophora atrata seem
to be somewhat more elongated and pointed (PL 3*, fig. 5) than those of
P. pedifera, and have a much shorter neck. The ophicephalous pedicellariae

28 TKOPICAL PACIFIC ECHINI.

(PL 3% fig. 6) have a comparatively smaller head and longer neck. The
triphyllous pedicellarice (PI. 3% fig. 7) are slightly larger, and the globiferous
pedicellarise (PI. 3% fig. 8) larger than those of P. 2:tedifera.

The tridentate pedicellarise of Colohocentrotus Mertensii (PI. 3% fig. 9)
are closely allied to those of P. atrata, as are also the ophicephalous
/of ones (PI. 3% fig.-7*). The triphyllous pedicellarice (PI. 3% fig. iO^ have a ///
/ proportionally shorter neck and larger head than in the two species named
above.

In the genus Podophora we find four kinds of pedicellarise : the ophi-
cephalous, tridentate, triphyllous, and globiferous. On Pis. 4-6 I have given
figures of the valves of the four kinds taken from different parts of tests of P.
pedifera. Their position is noted in the description of the Plates. The
figures will give a far better idea of the characteristics of the pedicellarioe than
any description I can give. Taking the figures of the valves of ophicephalous
pedicellariae of P. jjedifera (Pis. 4, figs. 1-6; 11-17; 6) one cannot
fail to be struck with the asymmetry of the valves, the great variation in
the size and arrangement of the foramina, in that of the hinges, of the serra-
tions of the edges, to say nothing of the great variation in the size of the
ophicephalous pedicellarias which vary from .33 mm. to .61 mm. in length ; we
note such extremes in the shape and the ornamentation of the ophicephalous
pedicellariae of P. pedifera as those of PI. 6 figs. 1, 2, U, 9, 10, 12, U, 16, 17,
taken from four individuals.

The valves of the globiferous pedicellarice of the same species (Pis. 4,
figs. 18-22; 5, figs. 10-13) taken from three specimens show equally great dif-
ferences in shape, size, and ornamentation; they vary from .21 mm. to .37 mm.
in length, and even of the triphyllous pedicellariaj figured (PI. 5, figs. 7-9) no
two of the valves are alike.

We finally come to the tridentate pedicellarife of P. pedifera (Pis. 4,
figs. 1-10; 5, figs. 1-6) varying in length from .86 mm. to .99 mm.
The figures are from pedicellarioe taken from five specimens, and they
speak for themselves. No two are alike, either in shape, size, outline, or
ornamentation.

The tridentate pedicellariae of P. atrata, figured on Pis. 18, figs.
1-6, 13-16; 19, figs. 1-13, were taken from three specimens. The valves vary
in length from .41 mm. to .90 mm. The blade of P. atrata is much more
elongate than the blade of P. pedifera. The variation in the serration of the
edge of the blade is very marked (compare PI. 18, figs. 6, 15, 16 with the same

THE GENUS COLOBOCENTROTUS. 29

edge of PI. 19, figs. 1, 2, 3, 10, 11). In one case the serration is limited to a
few large teeth, in the other the edge is serrated for the whole length of the
blade. The size and arrangement of the foramina of the valve both of the
basal part and of the blade also varies greatly. In many of the valves
the base passes very gradually into the blade (PI. 19, figs. 7-10), in others the
junction is sharply marked (PI. 18, figs. 4, 5), and in others the outline of the
base is quite irregular (PI. 18, figs. 1-3). It would be difficult to say which
of these pedicellarifB are typical of P. atrata ; as in P. pedifera the valves of
the triphyllous pedicellarite (Pis. 18, figs. 10-12; 19, figs. 14.-I6) vary greatly
in outline and in ornamentation. The valves figured were taken from two
specimens; they vary in length from .11 mm. to .16 mm.

Compared with the globiferous pedicellaritB of P. j^edifera, though they
vary greatly (Pis. 4, figs. 18-S2 ; 5, figs. 10-13), those of P. atrata (PI. 18, figs.
17, IS) do not show any important differences.

One of the ophicephalous pedicellarioe of P. atrata is figured on PI. 18, figs.
7-9. The edge of the valves is more finely serrated than in the majority of
the ophicephalous pedicellarise of P. 2)edifera, but some of them are fully as
finely serrated as those of P. atrata.

Owing to the great variation in the valves, neither the ophicephalous pedi-
cellarioe of Colob. Stimpsoni (PI. 29, figs. 1-6, 10-13, 16), varying in length
from .36 mm. to .51 mm., nor those of Coloh. Mertensii (PI. 30, figs. 1, 2, 9,
12-15), varying in length from .27 to .48 mm. show any character by
which it would be possible to distinguish these two species, or to dis-
tinguish them in turn from P. p)6difera or P. atrata. It is quite possible
to select ophicephalous pedicellariaa of P. pedifera and Coloh. Stimpsoni
which are very similar, and which it would be difficult to distinguish
(see PI. 6, fig. 10 and PI. 29, fig. 13). The valves of the triphyllous
pedicellarigB of Coloh. Stimpsoni (PI. 29, figs. H-15) appear to be somewhat
more slender than those of Coloh. Mei'tensii (PI. 30, figs. 10-11, 16), and the
foramina of the valves of the triphyllous pedicellariae of these two species are
perhaps, on the whole, smaller than those of P. pedifera and P. atrata.

The tridentate pedicellarioe of Coloh. Stimpsoni (PL 29, figs. 7-9) and those
of Coloh. Mertensii (PI. 30, figs. 3-8) resemble more the general pattern of
those of P. j)^difera, but in this case also the difference in the ornamentation
of the valves, in the proportions of the base to the blade makes it im-
possible to designate any one figure as a typical tridentate valve of either
species.

30 TROPICAL PACIFIC ECHINI.

The valves of the tridentate pedicellarite of Colob. Stimpsoni vary in length
from .78 mm. to .88 mm. ; those of Coloh. Mertensii from .41 to .81 mm.

The CySTACANTHS and SPHiERIDIA OF COLOBOCENTROTUS AND PODOPHORA.

Pis. 1-3 ; 31 ; 32.

A comparison of the sphaeridia of the species of Colobocentrotus and Podo-
phora shows at once how variable they are and how misleading their charac-
ters seem as guides to the affinities of the species of the genus. From a first
glance at the figures of Pis. 31 and 32, we would arrange on one side the more
or less cylindrical sphaeridia of P. jfedifera (PI. 31, figs, i-^), and the three
other species with globular sphaeridia on the other. Yet no one would attempt
to say that P. atrata is more closely allied to Colob. Stimpsoni and Colob.
Mertensii than to P. pedifera, as would be legitimate from the sphaeridia
alone.

PI. 13, fig. 5, shows a line of sphaeridia on the actinal part of the right
ambulacral zone. The great variation which exists in the sphisridia of P.
Ij^^jLoUa-O^ I -e4fmtu is well seen on comparing the figures of sphaeridia taken from different
' / parts of the same individual (measuring 8^ mm. in diameter, including the ^V

spines), viz., the left sphaerid of PI. 31, fig. 1, the left of fig. 2, the middle of '
fig. 3, and the right of fig. J!^, taken respectively from the right posterior am-
bulacrum, the odd anterior ambulacrum, the left anterior ambulacrum, and the
left posterior ambulacrum. They vary in length from .19 mm. to .34 mm.,
and in outline are cylindrical, elliptical, or club-shaped.

In P. «('/•«/« the variation in shape is not as marked (PI. 31, figs. 5-S),

yet there are such extremes in shape as the right sphrerid of PI. 31,

fig. 6, and the right sphaerid of PI. 31, fig. 7, the one measuring .2(j( mm., ^y

L I the other .23 mm. in length ; both were taken from the same specimen of

r/Y/eS mm. in diameter including the spines ; the one from the odd anterior ambu-

' lacrum, the other from the left posterior ambulacrum.

One might think, on examining the figures of Plate 32, that the sphferidia
of Coloh. Stimpsoni and Colob. Mertensii differed but little if the comparison is
made between such sphaeridia as PI. 32, figs. 1, ^, and PL 32, fig. 7, and the
central figure of fig. 5. When we come to compare such extremes of Colob.
Stimjjsoni as PI. 32, fig. 1, with the extremes of Cobb. Mertensii (PI. 32, fig. 6),
the differences are most striking ; while a comparison of the left figure of
PI. 32, fig. 7 {Coloh. Mertensii) with the left figure of PI. 32, fig. 8 {Colob.

THE GENUS COLOBOCENTROTUS. 31

Stimpsoni) would show that they are specifically identical ; again such
sphoeridia of Colob. Stimpsoni (PI. 32, fig. 4, right-hand figure) and the third
figure of PI. 32, fig. 6 (Colob. Mcrtensii) should leave no doubt of their specific
difference.

The sphaeridia of Colob. Stimpsoni were taken from the left posterior and
the left anterior ambulacra of a specimen measuring 88 mm. in diameter, and
those of Colob. Mertensii from the odd anterior and the left anterior ambula-
crum of a specimen measuring 7/ mm. in diameter including the spines, the O/
sphoeridia varying in length from .23 to .27 mm.

The great variation in the shape of the sphaeridia and of the pedicellariae,
depending in great measure on the position they occupy, does not seem to
make these organs important factors in the ultimate classification of Echini,
as has been maintained by some recent writers. At any rate, in the genera
Colobocentrotus and Podophora we have no basis, from the data obtained by
the examination of the pedicellarite, upon which to build the identification of
the species of this genus. We are led to the belief that while their examina-
tion is certainly most interesting and instructive as far as the general groups
of Echini are concerned, the application of the special details they furnish
can only bring about endless confusion when applied to the classification of
the genera and species of Echini, not only to the exclusion of other characters,
but also when given an inordinate importance in connection with other structural
features of the group.

While examining some specimens of P. pedifera Mr. M. Westergren
observed in the median line of the actinal part of one of the ambulacra pecu-
liar organs, a group of which has been figured on PI. 1, fig. 1. They might
at first sight be taken for clusters of poison glands of some globiferous pedi-
cellariae. These organs are small, the sacs with the spine rarely measuring
more than one millimeter in length. Five or six are found on the actinal side
of each ambulacrum (PI. 1, fig. l) . They consist in P. pedifera of three spheri-
cal sacs surrounded by an envelope (PI. 1, figs. 3, Ji). Each sac has a pore
which in the smaller organs has a more or less pentagonal shape. The larger
sacs seem when expanded to have forced out one or more transparent blad-
ders (PI. 1, figs. 2-^). I could not detect any spicules or other calcareous de-
posits in any of these diminutive organs which we may call cystacanths.
Only one of the sacs is attached to the extremity of a minute spine, greatly
resembling the rods of pedicellariae.

On PI. 1 are given a number of figures showing the cystacanths of P. pedifera

32 TROPICAL PACIFIC ECHINI.

from different sides. They are drawn from a dried specimen, the sacs having
been treated with alcohol and glycerine. The cystacanths of P. atrata differ
greatly from those of P. pedifera. The sacs are more closely compressed,
forming a club at the top of the rod (PI. 2, figs. 1-3). The bladders contained
in the sacs are much thicker than those of P. pedifera. The sacs are also
irregularly dotted with black spots. The cystacanths of P. atrata are found
on the abactinal extremity of the ambulacrum, close to the ocular plates, and
are absent from the actinal side. PI. 1, figs. 1, 2 are drawn from an alcoholic
specimen.

In Colob. Stivipsoni the cystacanths are comparatively larger (PI. 2,
figs. A-7), but coming from a dried specimen they have lost their globular
shape and the existence of pores could not be traced. The sacs seem tougher
than those of P. pedifera. In one of the figures (PI. 2, fig. 5) a few spicules
could be detected.

The cystacanths of Coloh. Mertensii (PL 2, figs. 8-12) are elongate, re-
sembling more those of Colob. Stimpsoni. They showed no pores. The spines
of the cystacanths (figs. 11, 12) resemble those of tridentate pedicellariae (PL

2, fig. 13) but they expand somewhat more at the tip.

In Chcetodiadema pallidum A. Ag. and Clark, cystacanths (PL 3) are found
only around the abactinal system, mainly upon the interambulacral plates.
They apparently vary far more in shape than in the species of Colobocentrotus
and Podophora. The cystacanths of PL 3, figs. 5, 6, 7, 8 are somewhat club
shaped like those of P. atrata. They show well developed pores (PL 3, figs, 2,

3, 5, 7, 11). Others (PL 3, fig. l) look more like the wrinkled sacs of the
cystacanths of Coloh. Stimpsoni. Others again consist only of a single
elongated sac (PL 3, figs. 2, 9). Transparent bladders like those seen in
P. jyedifera are seen on PL 3, figs. 1, 2, 11. It will be interesting to see if
cystacanths are found in other echini and to obtain, if possible, some clue
to the function of these problematical organs which suggest affinities both
to the poison glands of globiferous pedicellariaB and to the sac-carrying spines
of Echinothuriae.

On PL 12, figs. 8-10 of the Ingolf Ex. Echini, Dr. Mortensen gives sections
of an organ which remind one of cystacanths, but he calls them globiferous
pedicellariaB, though they seem to be without valves or other calcareous deposits.
He gives no further explanation of their structure in describing the glob-
iferous pedicellariae of Ilaplos. j^eUiicidum.

Cystacanths vary greatly in number in different specimens, and their occur-

THE GENUS COLOBOCENTKOTUS. 33

rence is not limited to the ambulacra near the sphasridia, nor are they limited
to the ambulacra. They are found both in the ambulacral and iuterambulacral
areas and on the actinal as well as the abactinal sides.

I can only o£Eer suggestions as to the nature of the cystacanths. I have no
observations of any value regarding their function. They may be modified sac-
bearing spines such as are found among the Echinothuriae or modified pedi-
cellarise in which the glands have developed into the glands of the cystacanths
at the expense of the valves.

if

EXPLANATION OF THE PLATES.

Plate 1.

Plate 1.

1-12. Podophora pedifera Agass.
1-11. Cystacanths from a specimen 82 mm. in diameter, including the spines.

1. Left posterior ambulacrum, actinal side, showing a group of cystacanths.

2. Expanded cystacanth, 0.92 mm.

3. Side view, of another specimen, 0.92 mm.

4. Seen from above, specimen of 0.90 mm.

6. Less developed with only three cysts, 0.66 mm.

6. Another stage with three cysts, 0.60 mm.

7. Showing the mode of attachment of the cysts to the spine, 0.71 mm.

8. Profile of cystacanth of 0.54 mm.

9. Same, front view.

10. Side view of one of the smallest cystacanths with three cysts, 0.41 mm.

11. The same, rear view.

12. Pedicellaria, to show its comparative size to the cystacanths.

All the figures equally magnified, measurements indicate the natural size of the sacs
■without the spine.

"Albatross' Tropical Pacific Ex 1899-1900.

GOLOBOCENTROTOS -PLATE 1.

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B.Meisel lilh.

Plate 2.

Plate 2.

1-3. Podophora atrata Agass.

1-3. Cystacanths from the abactinal side of a specimen 65 mm. in diameter, including
the spines.

1. From the left posterior ambulacrum, near the ocular plate, front view, 0.37 mm.

2. In the same ambulacrum, but less expanded, 0.39 mm.

3. Profile, from the same ambulacrum, 0.29 mm.

4-7. Colobocentrctus Stimpsoni A. Ag.
4-7. Cystacanths from a specimen of 88 mm. diameter with spines.

4. Shows the attachment of the spine to the third lobe, 0.94 mm. from the left anterior

ambulacrum, actinal side.

5. Front view of a cystacanth 0.60 mm. from the right anterior ambulacrum.

6. Same view of a cystacanth 0.58 mm. from the left posterior ambulacrum.

7. Profile of a cystacanth 0.70 mm. near the ambitus, from the right posterior ambula-

crum.

8-13. ColobocentrotuB Mertensii Brandt.

8-13. Cystacanths from a specimen 70 mm. in diameter including spines.

8. Contracted, with spine, 1.15 mm. close to the ambitus, from the odd anterior ambula-

crum.

9. Rear view, 0.44 mm. from the left anterior ambulacrum.

10. Seen from beneath, 0.59 mm. near the ambitus, from the left anterior ambulacrum.

11. Spine of a cystacanth.

12. Upper end of same, somewhat more magnified.

13. Spine of a pedicellaria.

All the figures are equally magnified; measurements indicate the natural size of the sacs
without spine.

"Albatross" Tropical Pacific Ex. 1899-1900.

COLOBOCENTROTUS PLATE 2.

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Plate 3.

Plate 3.

1-11. Chaetodiadema pallidum A. Ag. and CI.

1-11. Cystacanths, from the abactinal side of the amubulacral and iuterambulacral plates
round the summit of a specimen 65 mm. in diameter.

1. Front view of a somewhat contracted double cyst, 1 mm.

2. Single cyst, 1.30 mm. magnification of the drawing reduced one half.

3. Expanded, showing the pavement of epithelial cells and the two pores, 0.73 mm.

4. Shows a line of glands, 0.61 mm.

6. Cystacanth with epithelial cells, 0.66 mm.

6. Profile, showing a string of glands, 0.60 mm.

7. Front view with pores, 0.53 mm.

8. Cystacanths similar in form to fig. 7, 0.56 mm.

9. Profile of a cystacanth, 0.73 mm.

10. Younger stage, 0.55 mm.

11. Similar to fig. 10 with large pores, 0.36 mm.

The figures are equally magnified except 2 ; measurements give the natural size of the
cyst with its spine.

" Albatross " Ex. 1902. Station 4104.

<oss- Tropical Pacific Ex. 1899-1900.

COLOBOCENTROTUS PLATE 3.

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Plate 3a.

Plate 3a.

1-4. Podophora pedifera Agass.
From a specimen 74 mm. in diameter, including the spines.

1. Tridentate pedicellaria. 3.9 mm.

2. Ophicephalous pedicellaria. 2.9 mm.

3. Triphyllous pedicellaria. 2.2 mm.

4. Globiferous pedicellaria. 1.4 mm.

t
5-8. Podophora atrata Agass.

From a specimen 68 mm. in diameter, including the spines.

5. Tridentate pedicellaria. 2.1 mm.

6. Ophicephalous pedicellaria. 1.5 mm.

7. Triphyllous pedicellaria. 1.2 mm.

8. Globiferous pedicellaria. 1.4 mm.

9-11. Colobocentrotus Mertensii Brandt.
From a specimen 72 mm. in diameter, including the spines.

9. Tridentate pedicellaria. 2.7 mm.

10. Ophicephalous pedicellaria. 1.9 mm.

11. Triphyllous pedicellaria. 2.7 mm.

All the figures are of relative sizes and under the same enlargement; the measurements
indicate the greatest length of the pedicellarise in the positions in which they are drawn.

"Albatross"

Ex. 1899-1900.

i *

^'4

A.M.Westergreii(iel.

B.Meisel lift

Plate 4.

Plate 4.

1-22. Podophora pedifera Agass.
1-22. Valves of Pedicellarise.

1. Valve of an Ophicephalous pedicellaria, in profile, from the buccal membrane near the

teeth.

2. Valve of an Ophicephalous pedicellaria, another view of the same (fig. 1).

3. Valve of an Ophicephalous pedicellaria, interior of a valve of the same.

4. Valve of an Ophicephalous pedicellaria, similar to 3 ; exterior view.

5. Valve of an Ophicephalous pedicellaria, interior view of same.

6. Valve of an Ophicephalous pedicellaria, profile of same.

7. Valve of an Tridentate pedicellaria, from the right anterior ambulacrum, not far from

the actinal system.

8. Valve of a Tridentate pedicellaria, the same as 7 ; external view.
9 Valve of a Tridentate pedicellaria, the same as 7 ; internal view.

10. Valve of a Tridentate pedicellaria, the same as 7 ; profile of the articulation.

11. Valve of an Ophicephalous pedicellaria, from the left anterior ambulacrum, nearer the

ambitus than to the actinal system.

12. 13, 14. Details of the same pedicellaria as 11 ; articulations of each valve.

15. Valve of an Ophicephalous pedicellaria, from the left posterior interambulacrum, mid-

way between the actinal system and the ambitus.

16. Serration from same as 15.

17. Stalk and head of an Ophicephalous pedicellaria.

18. Valve of a Globiferous pedicellaria, from the apical part of the left anterior ambu-

lacrum.

19. Detail of an articulation seen from the exterior, the same as 18.

20. Interior the same as 18.

21. Exterior the same as 18.

22. View of the stalk and head of a globiferous pedicellaria.

The figures are about equally enlarged with the exception of 1-6, which are somewhat
larger.

Outer reef, Fakarava, Paumotus, " Albatross " Ex., 1899-1900.

"Albatross' Tropical Pacific Ex 1899-1900

COLOBOCENTROTUS PLATE 4-.

Meisel lilh

Plate 5.

Plate 5.

1-13. Podophora pedifera Agass.
1-13. Valves of Pedicellariae, seen from the exterior.

1. A valve of a Tridentate pedicellaria, 0.86 mm. from the left anterior ambulacrum, near

the actinal system of a specimen 73 mm. in diameter.

2. A valve of a Tridentate pedicellaria, 0.91 mm. from the left anterior ambulacrum, close

to the actinal system of a specimen 75 mm. in diameter.

3. A valve of a Tridentate pedicellaria, 0.94 mm. from the left posterior interambulacrum,

close to the actinal system, from the same specimen as 2.

4. A valve of a Tridentate pedicellaria, 0.98 mm. from the right anterior interambulacrum,

near the actinal system of a specimen 77 mm. in diameter.
6. A valve of a Tridentate pedicellaria, 0.99 mm. from the left anterior ambulacrum, close
to the actinal system of a specimen 80 mm. in diameter.

6. A valve of a Tridentate pedicellaria, 0.94 mm. from the right anterior ambulacrum

midway between the actinal system and the ambitus, from a specimen 82 mm. in
diameter.

7. A valve of a Triphyllous pedicellaria, 0.13 mm. from the right posterior ambulacrum,

at the ambitus, from a specimen 68 mm. in diameter.

8. A valve of a Triphyllous pedicellaria, 0.14 mm. from the odd anterior ambulacrum,

near the actinal system of the same specimen as 7.

9. A valve of a Triphyllous pedicellaria, 0.13 mm. from the left posterior ambulacrum,

midway between the actinal system and the ambitus of the same specimen as 7.

10. A valve of a Globiferous pedicellaria, 0.22 mm. from the odd anterior ambulacrum, near

the apical system, from a specimen 72 mm. in diameter.

11. A valve of a Globiferous pedicellaria, 0.37 mm. from the right posterior ambulacrum

near the actinal system of the same specimen as 10.

12. A valve of a Globiferous pedicellaria, 0.22 mm. from the odd anterior ambulacrum,

nearer the ambitus than the abactinal system, from a specimen 74 mm. in diameter.

13. A valve of a Globiferous pedicellaria, 0.21 mm. from the odd anterior ambulacrum, mid-

way between the ambitus and the abactinal system, from a specimen 83 mm. in
diameter.
The measurements of the diameter of the specimens include the spines. The dimensions
given of the pedicellaria are natural size. The corresponding valve was selected for each
figure.

Outer reef, Fakarava, Paumotus, " Albatross " Ex., 1899-1900.

"Albatross" Tropical Pacific Ex 1899 -li

COLOBOGENTROTUS PLATE 5.

/";-»?

A M.Wesiergren del

S-Meisel lilh

Plate 6.

Plate 6.

1-17. Podophora pedifera Agass.
1-17. Exterior views of valves of Opbicephalous pedicellariae.

1. A valve 0.35 mm. adjoining the teeth, from a specimen 73 mm. in diameter.

2. A valve 0.44 ram. adjoining the teeth, fiom a specimen 75 mm. in diameter.

3. A valve 0.36 mm. adjoining the teeth, from a specimen 82 mm. in diameter.

4. A valve 0.53 mm. from the right posterior ambulacrum, near the ambitus, of a speci-

men 68 mm. in diameter.

5. A valve 0.59 mm. from the right anterior ambulacrum, midway between the actinal

system and the ambitus of the same specimen as 4.

6. A valve 0.55 mm. from the left anterior ambulacrum, near the actinal system of the

same specimen as 4.

7. A valve 0.57 mm. from the right posterior interambulacrum, near the actinal system of

a specimen 72 mm. in diameter.

8. A valve 0.59 mm. from the left anterior interambulacrum, near the actinal system of

the same specimen as 7.

9. A valve 0.57 mm. from the right anterior ambulacrum, midway between the actinal

system and the ambitus of a specimen 73 mm. in diameter.

10. A valve 0.48 mm. from the right anterior ambulacrum, at the ambitus of a specimen

75 mm. in diameter.

11. A valve 0.59 mm. from the odd anterior ambulacrum, midway between the actinal system

and the ambitus, of the same specimen as 10.

12. A valve 0.61 mm. from the odd posterior interambulacrum, near the ambitus, of the

same specimen as 10.

13. A valve 0.57 mm. from the odd posterior interambulacrum, near the actinal system of

a specimen 77 mm. in diameter.

14. A valve 0.54 mm. from the left anterior interambulacrum, at the ambitus of a specimen

82 mm. in diameter.

15. A valve 0.56 mm. from the right posterior ambulacrum, midway between the actinal

system and the ambitus of a specimen 85 mm. in diameter.

16. A valve 0.48 mm. from the odd posterior interambulacrum at the ambitus of the same

specimen as 15.

17. A valve 0.38 mm. from the left posterior interambulacrum at the ambitus of the same

specimen as 15.

The measurements of the diameter of the test include the spines, with the exception of
1, 2, 4, 6, 6, 14, and 15, which are denuded. The corresponding valve was selected for
each figure. The figures are about equally magnified with the exception of 1-3, which
are somewhat larger. The dimensions given of the valves of the pedicellaria; are natural
size.

Outer reef, Fakarava, Paumotus, " Albatross" Ex., 1899-1900.

FROSs' TropicalPacifigEx. 1899-1900.

COLOBOv^

z 6.

AM

Plate 7.

Plate 7.

1-3. Podophora pedifera Agaes.

1. Seen from the actinal side.

2. The same specimen seen from the abactinal side.

3. The same specimen seen in profile, facing the odd anterior ambulacrum.

The odd anterior ambulacrum occupies the center of the upper part of figures 1 and 2.

All figures are natural size.

Outer reef, Fakarava, Paumotus, "Albatross" Ex., 1899-1900.

"Albatross" Tropical Pacihc Ex.i899-1900

COLOBOCENTROTUS PLATE "

He'i;ct)pf Co Boron

Plate 8.

Plate 8.

1-3. Podophora pedifera Agass.

1. Denuded test, seen from the actinal side.

2. The same specimen seen from the abactiual side.

3. The same specimen seen in profile, facing the odd anterior ambulacrum.
All figures are natural size.

The odd anterior ambulacrum occupies the center of the upper part of figs. 1, 2.
Outer reef, Fakarava, Paumotus, " Albatross " Ex., 1899-1900.

Albatross" TropicalPacific E>

CoLOBua::NTRO'rjs Plate 8

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Plate 9.

Plate 9.

1-6. Podophora pedifera Agass.

1. Denuded test, seen from the actinal side, measuring 55 mm. in diameter.

2. The same, from the abactinal side.

3. The same in profile, facing the odd anterior ambulacrum.

4. Actinal side of a specimen measuring 82 mm. in diameter, including the spines.
6. The same specimen seen from the abactinal side.

6. The same specimen seen facing the odd posterior interambulacrum.
The odd anterior ambulacrum occupies the center of the upper part of figures 1, 2, 4, 5.
Outer reef, Fakarava Paumotus, "Albatross" Ex., 1899-1900.

"Albatross" Tropical Pacific Ex 1899-1900

COLOBOCENTROTUS Pl^.TE 9.

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Plate 10.

Plate 10.

1-6. Podophora pedifera Agass.

1. Odd posterior interambulacrum, and left posterior with part of right posterior ambula-

crum, showing the grouping of the spines of a specimen measuring 75 mm. in diam-
eter, including the spines.

2. The same portion of the test as in 1 of a specimen, 76 mm. in diameter.

3. The same portion of the test as in 1 of a specimen 77 mm. in diameter.

4. The same portion of the test as in 1 of a specimen 80 mm. in diameter.
6. The same portion of the test as in 1 of a specimen 82 mm. in diameter.
6. The same portion of the test as in 1 of a specimen 87 mm. in diameter.

The dotted lines unite the primary radioles belonging to the same vertical row.
Outer reef, Fakarava, Paumotus, " Albatross " Ex., 1899-1900.

"Albatross" TropigalPacificEx, 1899-1900,

COLOBOCENTROTUS PLATE 10.

A.M.WeslHgren del

B Meisel lith

Plate U.

1-48. Podophora pedifera Agass.
1-48. Spines, from a specimen 82 mm. in diameter.

1. Spines seen in profile, taken from the left posterior ambulacrum towards the apical

system.

2. Spine, from a poriferous plate of the buccal membrane.

3. Spine, from the first plate at the actinal system of the odd anterior ambulacrum.

4. Spine, from the second plate, of the left anterior interambulacrum.

5. Spine, from the third plate, of the left anterior interambulacrum.

6. Spine, from the third plate, in the odd anterior ambulacrum.

7. The profile of the same spine as 6.

8. Spine, from the fourth plate of the left anterior ambulacrum.

9. Spine, f upper surface ■»

^„ _ . "i , . f- from the fourth plate of the odd anterior ambulacrum.

10. Spine, (. lower surface )

11. Spine, lower surface "l at the ambitus.

12. Spine, upper surface ^ from the fifth plate of the odd anterior ambulacrum.

13. Spine, profile J these larger radicles vary in length from 15 18 mm.

14. Spine, lower surface"]

15. Spine, upper surface |. from the sixth plate of the odd anterior ambulacrum.

16. Spine, profile J

17. Spine, lower surface \

. „ ^, . „ f from the seventh plate of the odd anterior ambulacrum.

18. Spine, upper surface >

19. Spine, lower surface ~|

20. Spine, upper surface > from the eighth plate of the odd anterior ambulacrum.

21. Spine, profile J

22. Spine, lower surface

23. Spine, top view ^ from the tenth plate of the left anterior interambulacrum.

24. Spine, profile

25. Spine, lower surface

26. Spine, top view

27. Spine, profile

28. Spine, lower surface

29. Spine, top view

30. Spine, profile

31. Spine, lower surface "

32. Spine, upper surface

33. Spine, profile
The plates from which the spine is taken are counted from the actinal system

34. Spine, lower surface

35. Spine, upper surface \~ from the ocular and genital plates

36. Spine, profile

from the eleventh plate of the left anterior interambulacrum.

from the twelfth plate of the odd anterior ambulacrum.

>. from the thirteenth plate of the odd anterior ambulacrum.

37. Spine, lower surface^

38. Spine, upper surface I- from the ocular and genital plates.

39. Spine, profile J

40. Spine, lower surface ")
., £, . . c from the ocular and genital plates.

41. Spine, upper surface > or

42. Spine, side view 1
.„ _, . . . f from the ocular and genital plates.

43. Spine, top view } or

44. Spine, lower surface ) , , , •> - , ,

>- from the ocular and genital plates.

45. Spine, top view )

46. SpiuB)

47. Spine,

48. Spine, ^
The figures are about equally magnified except 2, 3, 5, 8, and 46, which are enlargements

of adjoining figures in outline. The largest radicles at the ambitus measure 15-18 mm.
in length.
Outer reef, Fakarava, Paumotus, "Albatross" Ex., 1899-1900.

. spines, hidden by the big radicles, as seen in fig. 1.

"'^lbatross'Tropical Pacific Ex. i899-i900

31

32 33

22

^l

23

19

20

r

COLOBOCENTROTUS Pl^.TE 11.

29 28

3C

34- 35 36

12

1 »

/

13

37 38 39

r

10

41

42

14

B

if

10

43

16

n

44 45

17

%

5

1&

A.M.V/eHergrendel.

litllAiistiWemeriWntecPraiikfiirt'-M.

Plate 12.

Plate 12.
1-6. Podophora pedifera Agaes.

1. Left anterior interambulacrum.

2. The ninth and tenth interabulacral plates from the actinal system.

3. A tubercle, at the ambitus, from the seventh plate from the actinal system of the left

posterior interambulacrum.

4. The same tubercle, seen in profile.

5. Shows a group of miliaries, from the left anterior interambulacrum, abactinal side,

eleventh plate from the actinal system.

6. A genital plate and adjoining madreporite from the left anterior interambulacrum.
All the figures are taken from a denuded specimen, measuring 55 mm. in diameter.
Outer reef, Fakarava, Paumotus, " Albatross " Ex., 1899-1900.

'33" TropigalPacificEx 1899-1900.

COLOBOGENTROTUS PlATE 12..

A.M WestsigTm de!

Plate 13.

Plate 13.

1-8. Podophora pedifera Agass.

1. Interior view of the actinal side, with the lantern in place, odd ambulacrum at the top.

2. A pair of poriferous plates of the buccal membrane, facing the odd anterior ambula-

crum.

3. Exterior view of the odd anterior ambulacrum, at edge of the actinal system.

4. The same as 3, seen from the interior.

5. Right posterior ambulacrum, close to the actinal system, showing the sphseridia.

6. Fifth plate from the abactinal .system of the odd anterior ambulacrum, abactiual side,

exterior view, showing the arrangement of the pores.

7. Same as 6, interior view.

8. Ocular and abactinal ambulacral plates of the left posterior ambulacrum, seen from

the interior.

The figures are from same individual : 82 mm. in diameter, including the spines.
Outer reef, Fakarava, Paumotus, " Albatross " Ex., 1899-1900.

r Tropical Pacific Ex, 1899-1900.

COLOBOCENTROTUS Pi ATE 13.

', M.Weslergrcn dtl

i.Meisel lilh

Plate 14.

Plate 14.

1-9. Podophora pedifera Agass.

1. Abactinal system covered with spiues, of a specimen measuring 81 mm. in diameter.

2. Abactinal system of another specimen, 82 mm. in diameter, denuded of its large

spiues.

3. Exterior view of the abactinal system, denuded, showing the madreporite, genital pores

and anal system.

4. The same as 3, seen from the interior.

5. Auricles of the left anterior ambulacrum, seen looking towards the actinostome.

6. Auricles of left anterior ambulacrum, seen from the interior of the test.

7. Odd anterior ambulacrum adjoining the actinal system, seen from the interior, the

auricles having been removed.

8. Interior view of the interradial plates adjoining the actinal system of the riglit anterior

interambulacrum, showing the primordial plate.

9. The same as 8, of the odd posterior interambulacrum.

Figures 2 to 9 are drawn from the same individual, measuring 82 mm. in diameter,
including the spines.

Outer reef, Fakarava, Faumotus, "Albatross " Ex., 1899-1900.

"Albatross' TROPiCALPAcrpic Ex 1899-1900

COLOBOGENTROTUS PLATE 14.

&

^j=y^j

4q !2L^4i si

%rsft"'

A.M.Westergren del

- B Meisel lith

Plate 15.

Plate 15.
1-13. Podophora pedifera Agass.

1. Lantern seen from above.

2. The same as 1, seen in profile.

3. One of the pyramids seen from the exterior.

4. The same as 3, seen from the interior.
6. The same, seen in profile.

6. The same, seen from above.

7. a. Epiphysis of pyramid, seen from the interior, b. pyramid, in profile, seen from the

interior.

8. Detail of the corrugation on the edge of the inside wall of a pyramid.

9. a. Epiphysis of pyramid, seen from the exterior, b. pyramid in profile, seen from the

interior.

10. Upper end of a pyramid, exterior view showing a foramen.

11. a. Grooved tooth, b. dorsal view, c. seen in profile.

12. The brace, a. seen from above, b. same in profile, c. from below, d. endwise.

13. Compass, a. seen from above, b. the same in profile.

All the figures from a specimen measuring 82 mm. in diameter, including the spines.
Outer reef, Fakarava, Paumotus, " Albatross " Ex., 1899-1900.

u'ROss" Tropical Pacific Ex. I89y-l900.

//

V

COLOBOCENTROTUS PlATE 15.
]3

^''

7 a i

i

A.M Westei^n del

Plate 16.

Plate 16.

1-8. Podophora pedifera Agass.

1. The disk of an actinal pedicel, seen from above.

2. The same, seen from below.

3. Profile of the same.

4. Disk of an actinal pedicel, oblique view.

5. The disk of an actinal pedicel.

6. Central space of the disk of a pedicel, seen from below with yoke-shaped spicules,

7. Basal part of one of the lamince.

8. Spicule.

9-14. Podophora atrata Agass.

9. An actinal pedicel, seen from below the disk.

10. Actinal pedicel seen in profile.

11. Basal part of one of the laminee of the disk, from a specimen of 8 mm. in diameter.

12. Yoke-shaped spicule from the same specimen as 11.

13. Basal part of one of the laminae of the disk.

14. The tip of a dorsal pedicel.

The figures 1 to 8 are from a specimen of 82 mm. in diameter including the spines. With
the exception of 11, 12, the others are drawn from a specimen measuring 74 mm. in diam-
eter, including the spines.

Podophora pedifera from the outside reef, Fakarava, Paumotus, "Albatross" Ex.,
1899-1900.

P. atrata from the Hawaiian Ids., A. Garrett Coll.

"Albatross' Tropical Pacific Ex. 1899-1900

COLOBOCENTROTUS PlATI. 16

mM:

^

%

•'^">y.

--<pS5.

■-^-

^^X

/I ^

'.i W

A.M.Westergren del

B Meisei liLH-

>-

Plate 17.

1-19. Podophora atrata Agass.
1-19. Valves of pedicellariae.

Ophicephalous pedicellaria, from the buccal membrane close to

the teeth.
Ophicephalous pedicellaria, from the buccal membrane close to the

teeth, interior view.
Ophicephalous pedicellaria, from the buccal membrane close to the

teeth, exterior view, profile.
Ophicephalous pedicellaria, from the buccal membrane close to the

teeth, detail of articulation, exterior view.
Ophicephalous pedicellaria, from the buccal membrane close to the

teeth, detail of articulation, exterior view.
Valves from the same pedicellaria.
Ophicephalous pedicellaria, from the buccal membrane close to the

teeth, interior view.
Ophicephalous pedicellaria, from the buccal membrane close to the

teeth, interior view.
Ophicephalous pedicellaria, from the buccal membrane close to the

teeth, exterior view, magnified base of fig. G.

Ophicephalous pedicellaria, from the buccal membrane close to the

1. A valve 0.23 mm. "1

2. A valve 0.19 mm.

3. A valve 0.22 mm.

4. A valve 0.22 mm.

5. A valve 0.23 mm.

6. A valve 0.40 mm."

7. A valve 0.32 mm

8. A valve 0.40 mm. "

9. A valve 0.36 mm
10. A valve 0.32 mm

teeth, exterior view, magnified base of fig. 7.

13. A valve 0.47 mm.

14. A valve 0.47 mm.

Ophicephalous pedicellaria, from the buccal membrane close to the
teeth, exterior view, magnified base of fig. 7.

11. A valve 0.47 mm. Tridentate pedicellaria, from the actinal side of the left anterior

ambulacrum.

12. A valve 0.44 mm. Tridentate pedicellaria, interior view from the right anterior am-

bulacrum.
Tridentate pedicellaria, exterior view, profile, from the right ante-
rior ambulacrum.
Tridentate pedicellaria, interior view, profile, from the right ante-
rior ambulacrum.
From the same pedicellaria.
15. A valve 0.26 mm. I Ophicephalous pedicellaria, near the ambitus from the actinal side

> of the right posterior interambulacrum.
IG. A valve 0.26 mm. J Opliiceplialous pedicellaria, serration of edge, same jjedirellari i

as 15.

17. A valve 0.24 mm. Ophicephalous pedicellaria, interior view from the abactinal side of

the right posterior interambulacrum.

18. A valve 0.11 mm.l Globiferous pedicellaria, exterior view from the abactinal side of

y the left posterior ambulacrum.

19. A valve 0.11 mm. J Globiferous pedicellaria, profile, same pedicellaria as 18.

Figures 1-5 are the same pedicellaria, from a specimen 8 mm. in diameter ; 6-10, from
a specimen 74 mm. in diameter ; and 11-19 from a specimen 8 mm. in diameter, including
the spines.

The measurements give the natural size. The enlargement of the figures is about the
same, excepting 6, 7, and 8, 9, 10, which are somewhat larger.

Hawaiian Ids., A. Garrett, Coll.

"Albatross' Tropical Pacific Ex 1899-1900.

COLOBOCENTROTUS PLATE 17.

//

17

16

15

18

19

15 H

10

A M. We3ia|ren del

B.Meisel Kth

Plate 18.

Plate 18.

1-18. Podophora atrata Agass.
1-18. Valves of pedicellarise.

Tridentate pedicellaria, from the buccal membrane close to the
teeth, exterior view.

Tridentate pedicellaria, from the buccal membrane close to the
teeth, exterior view.

Tridentate pedicellaria, from the buccal membrane close to the
teeth, interior view

Tridentate pedicellaria, from the left anterior ambulacrum, not
far from actinal system, exterior view.

Tridentate pedicellaria, from the left anterior ambulacrum, in-
terior view.

Tridentate pedicellaria, from the left anterior ambulacrum, in-
terior view profile.

Ophicephalous pedicellaria from the right anterior ambulacrum 1,
midway between the actinal system and the ambitus, interior
>- view.

Ophicephalous pedicellaria, same pedicellaria as 7, interior view.

Ophicephalous pedicellaria, same pedicellaria as 7, interior view.
10. A valve 0.16 mm. >, Triphyllous pedicellaria, from the odd anterior ambulacrum

among the sphajridia, exterior view.
* Triphyllous pedicellaria, same pedicellaria as 10, interior view.

Triphyllous pedicellaria, same pedicellaria as 10, exterior view,
profile.

Tridentate pedicellaria, from the actinal side of the left anterior
iuterambulacrum, near the ambitus, exterior view.

Tridentate pedicellaria, same as 13, interior view.

Tridentate pedicellaria, same as 13, exterior view, profile.

Tridentate pedicellaria, from the right anterior ambulacrum, mid-
way between the ambitus and the abactinal system, interior
view.

Globiferous pedicellaria from the odd anterior ambulacrum near
>■ the ocular plate, interior view.

Globiferous pedicellaria, same as 17, exterior view, profile.

The valves are taken from the same specimen, measuring 74 mm. in diameter, in-
cluding the spines.

The measurement of the figures gives the natural size ; the enlargement of the valves of
each pedicellaria is the same, but the enlargement of the different pedicellarise is not
identical.

Hawaiian Ids., A. Garrett Coll.

1. A valve 0.67 mm.

2. A valve 0.65 mm.

3. A valve 0.63 mm.

4. A valve 0.85 mm.

5. A valve 0.88 mm.

6. A valve 0.87 mm.

7. A valve 0.57 mm.

8. A valve 0.50 mm.

9. A valve 0.48 mm.

11. A valve 0.15 mm.

12. A valve 0.16 mm.

13. A valve 0.49 mm.

14. A valve 0.47 mm.

15. A valve 0.48 mm.

16. A valve 0.39 mm.

17. A valve 0.24 mm.

18. A valve 0.21 mm.

"Albatross' TROPrcAX Pacific Ex 1899-1900.

COLOBOCENTROTUS PLATE 18.

11

14

13

A.M.WestEi^ren ael

i.Meisel lith

Plate 19.

Plate 19.

1-16. Podophora atrata Agass.
1-16. Valves of pedicellarias.

1. A valve 0.53 mm. Tridentate pedicellaria, exterior view, near the actinal system,

from the right posterior ambulacrum of a specimen 18 mm. in diameter, including
the spines.

2. A valve 0.55 mm. Tridentate pedicellaria, near the actinal system, from the left pos-

terior ambulacrum, same specimen as 1.

3. A valve 0.71 mm. Tridentate pedicellaria, midway between the actinal system and

the ambitus, from the right anterior ambulacrum of a specimen 35 mm. in diameter,
including the spines.

4. A valve 0.66 mm. Tridentate pedicellaria, midway between the actinal system and

the ambitus, from the odd anterior ambulacrum, same specimen as 3.

5. A valve 0.84 mm. Tridentate pedicellaria, at the ambitus, from the left anterior

ambulacrum, same as 3.

6. A valve 0.83 mm. Tridentate pedicellaria, midway between the actinal system and

the ambitus, from the odd posterior interambulacrum, same as 3.

7. A valve 0.81 mm. Tridentate pedicellaria, near the actinal system, from the right

posterior ambulacrum of a specimen 67 mm. in diameter, including the spines.

8. A valve 0.85 mm. Tridentate pedicellaria, near the actinal system, from the left

anterior ambulacrum, same specimen as 7.

9. A valve 0.90 mm. Tridentate pedicellaria, midway between the actinal system and

the ambitus, from the left posterior ambulacrum, same as 7.

10. A valve 0.82 mm. Tridentate pedicellaria, at the ambitus, from the right posterior

ambulacrum, same as 7.

11. A valve 0.47 mm. Tridentate pedicellaria, midway between the ambitus and the

abactinal system, from the left anterior ambulacrum, same as 7.

12. A valve 0.74 mm. Tridentate pedicellaria, on the actinal side of the ambitus, from

the right posterior ambulacrum, same as 7.

13. A valve 0.41 mm. Tridentate pedicellaria, near the ocular plate, from the left anterior

ambulacrum, same as 7.

14. A valve 0.14 mm. Triphyllous pedicellaria, near the actinal system, from the left

anterior ambulacrum, same as 7. ■

15. A valve 0.12 mm. Triphyllous pedicellaria, from the abactinal side of the ambitus,

from the right posterior ambulacrum, same as 7.

16. A valve 0.11 mm. Triphyllous pedicellaria, near the apical system, from the left

anterior ambulacrum, same as 7.
The same valve in each pedicellaria is figured. The enlargement of the figures is about
the same. All the figures present an exterior view.
Hawaiian Ids., A. Garrett Coll.

"Albatross" Tropical Pacific Ex 1899-1900.

CO!

^'

V

10

/^^a

A.M,

:n dei

B Meisel lith

Plate 20.

Plate 20.

1-6. Podophora atrata Agaes.

1. Seen from actinal side.

2. The same as 1 seen from actinal side denuded of its spines.

3. The same seen from the abactinal side.

4. Seen from the abactinal side, denuded of its spines.

5. Seen in profile facing the odd posterior interambulacrum.

6. The same denuded, facing the odd anterior ambulacrum.

The odd anterior ambulacrum occupies the center of the upper part of figs. 1, 2, 3,
and 4.

All figures are natural size.
Hawaiian Ids., A. Garrett Coll.

rVLL

: ACinc E:

^ff^

i^'f^^ff^-.'-

.4fc^cS!^

^hM

■'-^

Hehotype Co. Boi-fon

Plate 21.

Plate 21.

1-6. Podopbora atrata Agass.

1. Denuded test, seen from the actinal side.

2. The same seen from the abactinal side.

3. Seen iu profile facing the odd anterior ambulacrum.

4. Seen from the actinal side.

5. The same seen from the abactinal side.

6. Profile of the same, facing the odd posterior interambulacrum.
All figures are natural size.

The odd anterior ambulacrum occupies the center of the upper part of figures 1, 2, 4, 5.
Hawaiian Ids., A. Garrett coll.

;3" Tropical Pacific Ex 1899-1900.

L

COLOBOCENTROTUS -; a" 21.

L^.'^:^

'^.^';:.

"-^-^ay

■:^.--- ^.i -- ^.. ^."'/'-i

i.^^'^i

J,' ^

- ^' -■.

kV, V/esur^CT"' ce'

Plate 21a.

Plate 21a.

1-3. Fodophora atrata Agass.

1. Specimen with club-shaped primary radioles, seen from the actinal side.

2. The same as fig. 1, seen from the abactiual side.

3. The same seen in profile facing the odd posterior interambulacrura.
The odd anterior ambulacrum is at the top of figures 1 and 2.

This specimen measures 92 mm., and was collected at Mauritius.

"Albatross" TROPiGAi.rAC;iior_>'., loas-isu.,-

COLOBOCENTROTUS PLATE. 21?

/

Plate 21b.

Plate 21b.

1-3. Podophora atrata Agasi.

1. Test seen from the actinal side.

2. The same seen from the abactinal side.

3. The same in profile facing the odd interambulacrum.

This specimen measures 97 mm. including the spines, collected at Mauritius by Nicolas
Pike.

i--i.L.j3-".i ri.L*

55" TropicalPacific Ex. 1899-1900.

GOLOBOCENTROTUS PLATE 21''

IM

Plate 22.

Plate 22.

1-10. Podophora atrata Agass.

1. From a specimen 12 mm. in diameter, including the spines.

2. From a specimen 14 mm. in diameter, including the spines.

3. From a specimen 18 mm. in diameter, including the spines.

4. From a specimen 26 mm. in diameter, including the spines.

5. From a specimen .31 mm. in diameter, including the spines.
G. From a specimen 35 ram. in diameter, including the spines.

7. From a specimen 46 mm. in diameter, including the spines.

8. From a specimen 67 mm. in diameter, including the spines.
.9. From a specimen 74 mm. in diameter, including the spines.

10. From a specimen 77 mm. in diameter, including the spines.

The figures show the order of growth of the spines ; the same view is given for each spe-
cimen, showing the left posterior ambulacrum, the odd posterior iuterambulacrum in the
center, and one half of the right posterior ambulacrum.

The dotted lines join the radioles of the same vertical row.

Hawaiian Ids., A. Garrett Coll.

"Albatross' TROPiCALPAcrFicEx. 1899-1900.

COLOBOCENTRC^

22.

,-v;--^,-'

A M Westegren del

B.Meisel lift.

Plate 23.

1-33. Podophora atrata AgasB.
1-33 Spines.

1. Spine, from the actinal system near tlie teeth.

2. Spine, near the actinal system, from the odd anterior ambulacrum,

3. Spine, ^ lower surface, near the actinal system, from the left anterior interambu-

lacrum.

4. Spine, y upper surface, near the actinal system, from the left anterior interambu-

lacrum.

5. Spine, J profile, near the actinal system, from the left anterior interambulacrum.

6. Spine, ■^ upper surface, from the actinal side of the ambitus, from the left posterior

interambulacrum.

7. Spine, lower surface, from the actinal side of the ambitus, from the left posterior

interambulacrum.

8. Spine, profile, from the actinal side of the ambitus, from the left posterior inter-

J ambulacrum.

9. Spine, ^ upper surface, at the ambitus, from the right anterior ambulacrum.

10. Spine, > lower surface, at the ambitus, from the right anterior ambulacrum.

11. Spine, J profile, at the ambitus, from the right anterior ambulacrum.
These larger radioles vary in length from 15-20 mm.

12. Spine, ] upper surface, at the ambitus, from the left posterior interambulacrum.

13. Spine, ?■ lower surface, at the ambitus, from the left posterior interambulacrum.

14. Spine,J profile, at the ambitus, from the left posterior interambulacrum.

15. Spine, ] lower surface, from the abactinal side, near the ambitus, from the right pos-

terior ambulacrum.

16. Spine, I top view, from the abactinal side, near the ambitus, from the right posterior

ambulacrum.

17. Spine, profile, from the abactinal side, near the ambitus, from the right posterior

ambulacrum.

18. Spine, ^ upper surface, from the abactinal side, near the ambitus, from the right ante-

rior interambulacrum.

19. Spine, I lower surface, from the abactinal side, near the ambitus, from the right ante-

rior interambulacrum.

20. Spine, profile, from the abactinal side, near the ambitus, from the right anterior

interambulacrum.

21. Spine, ^ lower surface, from the abactinal side, near the ambitus, from the right ante-

rior interambulacrum.

22. Spine, I top view, from the abactinal side, near the ambitus, from the right anterior

interambulacrum.

23. Spine, profile, from the abactinal side, near the ambitus, from the right anterior

interauibulacrum.

side view, from the abactinal side, near the ambitus, from the right posterior

interambulacrum.
profile, from the abactinal side, near the ambitus, from the right posterior

interambulacrum.
lower side, midway between the ambitus and the abactinal side, from the

right posterior interambulacrum.
profile, midway between the ambitus and the abactinal side, from the right

posterior interambulacrum.
top view, midway between the ambitus and the abactinal side, from the right

posterior interambulacrum.
lower surface, from the genital plates,
profile, from the genital plates.
top view, from the genital plates.

32. Spine, side view, from the madreporic plate.

33. Spine, from the abactinal side of the right posterior interambulacrum. These spines

are hidden under the big primary radioles (see PI. 11, fig. 1).
The enlargement of the figures is about the same. The shaded figs. 1, 2, and 33 are
drawn on a larger scale.
Hawaiian Ids., A. Garrett Coll.

24.

Spine, '

25.

Spine,

26.

Spine, '

27.

Spine,

28.

Spine,

29.

Spine,

30.

Spine,

31.

Spine, _

'Albatross" Tropical Pacific Ex, 1899-1900,

7

CoLOBocEMTROTus. Plate 23.

21

Iff

22

23

25 24

32

i '

10

26

*^

19

30

29

,«•

Jl^^

28

27

18

t'ni

A

20

-^

31

12

13

14-

'-^^^-

'^.

^

■3

^

% I 33

Aj^

y

l&l

16

15

17

A.M.Westergreii del

litliJir6lvWemer4Wmtei;Franl!furt''-M.

Plate 24.

Plate 24.

1-8. Podophora atrata Agass.

1. Left anterior interambulacrum of a denuded specimen measuring 8 mm. in diameter.

2. The same interambulacrum from a denuded specimen 14 mm. in diameter.

3. The same interambulacrum from a denuded specimen 26 mm. in diameter.

4. The same interambulacrum from a denuded specimen 45 mm. in diameter.

5. A primary tubercle at the ambitus, on the fifth plate from the actinal system, the de-

nuded test measuring 45 mm. in diameter.

6. The same, tubercle in profile.

7. The genital and last interambulacral plates, the seventh and eighth from the actinal

system in the left anterior interambulacrum, of a denuded specimen, measuring
8 mm. in diameter.

8. The ninth and tenth plates of the left anterior interambulacrum, of a denuded test

measuring 45 mm. in diameter.
Hawaiian Ids., A. Garrett Coll.

"Albatross" Tr opical Pacific Ex^ 1899-1900.

COLOBOCENTROTUS PLATE 24.

'0.

J.

A.M.Westergren del

S Meisel lilh

Plate 25.

Plate 25.
1-10. Podophora atrata Agass.

1. Seen from abactinal side, with spines, measuring 14 mm. in diameter.

2. The same, denuded, seen from the actinal side, measuring 8 mm. in diameter.

3. The same seen from the abactinal side.

4. Profile of the same, facing the bivium and the odd posterior interambulacrum.

5. Interior view of the test of the same showing the abactinal system.

6. Left posterior ambulacral plates adjoining the actinal system,

7. Odd anterior ambulacrum at the ambitus.

8. Part of the abactinal system, the left anterior interambulacral and genital plates.

9. The odd anterior ambulacral plates adjoining the actiual system, of a denuded speci-

men measuring 45 mm. in diameter.
10. The same ambulacrum, partly on the actinal, and partly on the abactinal side of the

ambitus.
Figures 1 to 8 are drawn from the same denuded specimen, measuring 8 mm. in diameter.
Hawaiian Ids., A. Garrett Coll.

"Albatross" Tropical Pacific Ex 1899-1900.

COLOBOCENTROTUS PLATE 25.
3

J -"^ V^-'^-

7(9

A M WR!5teiTTeri dtil

Plate 26.

Plate 26.

1-16. Podophora atrata AgasB.

1. Abactinal system, denuded of spines, of a specimen measuring 8 mm. in diameter.

2. The same, measuring with spines 14 mm. in diameter.

3. Abactinal system of a specimen measuring with spines 74 mm. in diameter, and

denuded 45 mm.

4. Abactinal system, covered with spines, of a specimen measuring 77 mm. in diameter.

5. Anal system of a specimen 8 mm. in diameter.

6. Anal system of a specimen 14 mm. in diameter.

7. Anal system of a specimen 26 mm. in diameter.

8. Anal system of a specimen 45 mm. in diameter.

9. The auricles of the right anterior ambulacrum, seen from the interior of the test of a

specimen 8 mm. in diameter.

10. The auricles of the left posterior ambulacrum, looking towards the actinostome, same

specimen as 9.

11. Actinal part of the odd posterior interambulacrum, interior view of a specimen 8 mm.

in diameter.

12. Auricles of the odd anterior ambulacrum, seen from the interior of the test of a speci-

men 14 mm. in diameter.

13. The same ambulacrum as 12 from a specimen 45 mm. in diameter.

14. Part of the odd anterior ambulacrum, seen from the interior.

15. Exterior view of the ocular and ambulacral plates of the left posterior ambulacrum of

a specimen 8 mm. in diameter.

16. The same seen from the interior.

Figures 1, 5, 9-11, 15 and 16, are drawn from the same individual.
Hawaiian Ids., A. Garrett Coll.

Tropical Pacific Ex, 1899-1900.

COLOBOCEiNTROTUS PLATE 26

AM.WesteifTjndel

B Meisel lilh

Plate 27.

Plate 27.

1-14. Podophora atrata Agass.

1. Lantern seen from above.

2. The same as 1, seen in profile.

3. One of the pyramids, seen from the exterior.

4. The same as 3, seen from the interior.

5. The same seen in profile.

6. The same seen from above.

7. Pyramid, in profile, from the interior.

8. a. Epiphysis of pyramid, from the outside, b. top of a pyramid, in profile.

9. A tooth still in its socket.

10. a. Groove of tooth ; b. dorsal view of tooth, c. seen in profile.

11. Part of 10 c. enlarged.

12. Upper part of tooth.

13. a. The brace, seen from above, b. seen in profile, c. from below, d. endwise.

14. a. Compass seen from above, b. the same in profile.

All the figures are taken from a denuded specimen measuring 8 mm. in diameter.
Hawaiian Ids., A. Garrett Coll.

"Albatross" Tropical PAcrFic Ex 1899-1900

COLOBOCENTROTUS- PLATE 27

4

#

4

'G^'f

K-^

n

Aft

06

11

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yi'

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A-M Weslergren del

BMeisel lift

Plate 28.

Plate 28.

1-11. Podophora atrata Aga83.

1. Lantern, seen from above.

2. The same as 1, seen in profile.

3. One of the pyramids, seen from the exterior.

4. The same seen from the interior.
6. The same seen in profile.

6. Same seen from above.

7. a. Epiphysis of pyramid seen from the inside, b. pyramid seen in profile from the

interior.

8. a. Epiphysis of pyramid from the exterior, b. upper end of a pyramid seen from the

exterior.

9. a. Groove of tooth, b. dorsal view of tooth, c. seen in profile.

10. a. The brace, seen from above, b. seen in profile, c. from below, d. endwise.

11. a. Compass seen from above, b. the same in profile.

The figures are drawn from a denuded specimen 45 mm. in diameter.
Hawaiian Ids., A. Garrett Coll.

'Albatross' Tropical. Pacific Ex, 1899-

COLOBOGENTROTLTS PlATF, 28

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1

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i

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Plate 29.

Plate 29.

1-17. ColobocentrotuB Stimpsoni A. Ag.

1-17. Valves of pedieellarise.

1. A valve 0.41 mm. of an Ophicephalous pedicellaria, exterior view, near the teeth.

2. A valve 0.36 mm.

3. A valve 0.48 mm.

4. A valve 0.50 mm.

6.

A valve 0.51 mm.

6.

A valve 0.51 mm.

7.

A valve 0.88 mm.~

8.

A valve 0.78 mm.

9.

A valve 0.86 ram..

10.

A valve 0.47 mm.

11.

A valve 0.47 mm.

Ophicephalous pedicellaria, interior view, near the teeth.
Ophicephalous pedicellaria, exterior view, nearer the actinal system

than the ambitus, from the odd anterior ambulacmm.
Ophicephalous pedicellaria profile, interior view, nearer the actinal

system than the ambitus, from the right anterior ambulacrum.
Ophicephalous pedicellaria, interior view.

Ophicephalous pedicellaria, midway between the actinal system
and the ambitus, from the left anterior ambulacrum.
Tridentate pedicellaria, exterior view, not far from the actinal
system, from the left posterior ambulacrum.
Tridentate pedicellaria, interior view.
Tridentate pedicellaria, profile, exterior view.
Ophicephalous pedicellaria, showing the articulation near the am-
bitus, from the left anterior iuterambulacrum.
Ophicephalous pedicellaria, interior view, nearer the ambitus than

the actinal system, from the right anterior interambulacrum.
Ophicephalous pedicellaria, interior view near the ambitus, from
the right anterior interambulacrum.

Ophicephalous pedicellaria, exterior view midway between the
ambitus and the abactinal system, from the right anterior inter-
ambulacrum.
A valve 0.17 mm. Triphyllous pedicellaria, midway between the actinal system and
the ambitus, from the left anterior interambulacrum.
Triphyllous pedicellaria, from the same, interior view of a single

valve.
Ophicephalous pedicellaria, interior view not far from the ocular
plate, from the left posterior ambulacrum.
Triphyllous pedicellaria, exterior view close to the ocular plate,
of the right posterior ambulacrum.
The enlargement of the pedicellaria of the actinal system is somewhat greater than that
of figs. 7-9 which are drawn on a smaller scale.

All the figures are from a specimen 88 mm. in diameter including the spines. Collected
by Dr. Wm. Stimpson at the Benin Ids.

12. A valve 0.47 mm.

13. A valve 0.36 mm.

14

15. A valve 0.16 mm.

16. A valve 0.34 mm.

17. A valve 0.9 mm.

:ross° Tropical Pacific Ex- 1899-1900.

COLOBOCENTROTUS PLATE 29.

A M Westei|ren de!

B.Meisel.lith

Plate 30.

Plate 30.

A valve 0.78 mm.
A valve 0.77 mm.

7. A valve 0.41 mm.

8. A valve 0.47 mm.

10. A valve 0.12 mm.

11. A valve 0.14 mm.

12. A valve 0.46 mm.

13. A valve 0.44 mm.

14. A valve 0.31 mm.

15. A valve 0.27 mm.

16. A valve 0.9 mm.

1-16. Colobocentrotus Mertensii Brandt.

1-1 6. Valves of pedicellarise.

1. A valve 0.38 mm. > Ophicephalous pedicellaria, interior view near the teeth.

2. A valve 0.35 mm. ' Ophicephalous pedicellaria, exterior view, near the teeth.

3. A valve 0.81 mm. "| Tridentate pedicellaria, exterior view, close to the actinal system

from the odd anterior ambulacrum.

Tridentate pedicellaria, interior view of the same pedicellaria as 3.

Tridentate pedicellaria, profile, interior view of the same as 3.
6. A valve 0.54 mm. ] Tridentate pedicellaria, exterior view, midway between the ambitus

and the actinal system, from the left posterior ambulacrum.

Tridentate pedicellaria, interior view, from the left posterior am-
bulacrum.

Tridentate pedicellaria, close to the ambitus, from the right an-
terior ambulacrum.
9. A valve 0.48 mm. Ophicephalous pedicellaria, exterior view, close to the ambitus,
from the right anterior ambulacrum.

Triphyllous pedicellaria, exterior view, midway between the actinal
system and the ambitus, from the left anterior ambulacrum.

Triphyllous pedicellaria, profile, same pedicellaria as 10.

Ophicephalous pedicellaria, interior view close to the ambitus,
from the right anterior interambulacrum.

Ophicephalous pedicellaria, exterior view of same pedicellaria as
12.

Ophicephalous pedicellaria, interior view midway between the am-
bitus and the abactinal system, from the left posterior interam-
bulacrum. *

Ophicephalous pedicellaria, exterior view of the same pedicellaria
as 14.

Triphyllous pedicellaria, exterior view, close to the ocular plate,
from the right anterior ambulacrum.
From a specimen measuring 70 mm. in diameter, with spines.
Bonin Ids., N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

^,

■.Qss" Tropical Pacific Ex. 1889-1900.

COLOBOCENTROTUS PLATE 30.

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Plate 31.

Plate 31.

1-4. Podophora pedifera Agass.
1-8. Sphaeridia.

1. Sphseridia, the first measures 0.27 mm. in length, all from the right posterior ambu-

lacrum.

2. From the odd anterior ambulacrum, the longest measures 0.34 mm., the length of its

mate is 0.29 mm.

3. The first figure measures 0.28 mm., the second 0.19 mm., from the left anterior ambu-

lacrum.

4. From the left posterior ambulacrum, the first figure measures 0.26 mm.

5-8. Podophora atrata Agass.

5. Three sphaeridia from the right posterior ambulacrum, the middle one measures 0.26

mm.

6. From the odd anterior ambulacrum, the second figure measures 0.25 mm.

7. Sphseridia from the left anterior ambulacrum, the third figure measures 0.26 mm.

8. From the left posterior ambulacrum, the second figure measures 0.29 mm.

The sphaeridia of 1-4 are from the same specimen, measuring 85 mm. in diameter, in-
cluding the spines, and those of 5-8 are from an individual measuring 77 mm.
The enlargement of the figures is about the same.

Albatross" TROPiCALPACiFir !■^' i.=.w .

COLOBOCENTROTU;

31

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Plate 32.

Plate 32.

1-4. Colobocentrotus Stimpsoni A. Ag.

1-8. Sphseridia.

1. Spboeridia, the second measures 0.25 mm. in length ; all the sphaeridia are from the

right posterior ambulacrum.

2. From the odd anterior ambulacrum, the first measures 0.26 mm. in length.

3. The second figure measures 0.27 mm. in length ; from the left anterior ambulacrum.

4. From the left posterior ambulacrum, the first figure measures 0.22 mm. in length, the

second 0.27 mm.

6-8. Colobocentrotus Mertensii Brandt.

5. Three sphseridia from the right posterior ambulacrum, the last one measuring 0.26 mm.

in length.

6. From the odd anterior ambulacrum, the first figure measures 0.27 mm. in length and

the fourth one 0.23 mm.

7. Sphseridia from the left anterior ambulacrum, the second figure measures 0.25 mm. in

length.

8. From the left posterior ambulacrum, the first figure measures 0.28 mm. in length.
The sphseridia of 1-4 are from the same specimen, 88 mm. in diameter, including the

spines and those of 5-8 from an individual measuring 70 mm.
The enlargement of the figures is about the same.
Benin Ids., N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

"Albatross' TropicalPaciftc Ex 1899-1900^

COLOBOCENTROTUS '-A .\Z7. 32.

i> r^^

r del

B.f.'

Plate 33.

Plate 33.
1-3. ColobocentrotuB Stimpsoiii A. Ag.

1. Seen from the actinal side.

2. Seen from the abactinal side.

3. The same specimen, seen in profile, facing the odd anterior ambulacrum.

The odd anterior ambulacrum occupies the center of the upper part of figures 1, 2.

All figures are natural size.

Bonin Ids., Captains Einggold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

■Albatross'

Plate 33.

W>

Heiiot->prCo.Eo:Tfir,

Plate 34.

Plate 34.

1-3. Colobocentrotua Stimpsoui A. Ag.

1. Seen from the actinal side ; denuded of its spines.

2. The same seen from the abactiual side.

3. The same specimen, seen in profile, facing the odd anterior ambulacrum.
All figures are natural size.

Bonin Ids., Captains Ringgold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

'Albatross ''Tropical Pacific Ex1899-1900

COLOBOCENTROTUS PLATE 34.

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Heiiotype Co, Boston

Plate 35.

Plate 35.

1-3. Colobocentrotus Mertensii Brandt.

1. Seen from the actinal side.

2. Seen from the abactinal side.

3. The same specimen, seen in profile, facing the odd anterior ambulacrum.
All figures are natural size.

The odd anterior ambulacrum occupies the center of the upper part of figs. 1, 2.
Bonin Ids., Captains Ringgold and Rodgers, K P. Ex. Ex., Dr. Wm. Stimpson Coll.

\lbatross "Tropical Ra.cific Ex1899-1900

_.uuuB'ju.iviRi.'!i;i Plate 35.

Hekoh'pe Co. Boston,

Plate 36.

Plate 36.
1-3. Colobocentrotus Mertensii Brandt.

1. Seen from the aetinal side.

2. The same seen from the abactinal side.

3. The same specimen, seen in profile, facing the bivium and odd posterior interam-

bulacrum.
All figures are natural size.
Bonin Ids., Captains Ringgold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

'Albatross'Tropical Pacific Ex-1899-1900.

COLOBOCENTROTUS PLATE 36

/

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'■'-•iU^^s

Hdiolype Co Bosta.

Plate 37.

Plate 37.
1-3. Colobocentrotua Stimpsoni A. Ag.

1. Seen from the actinal side, measuring 88 mm. in diameter including the spines.

2. The same seen from the abactinal side.

3. Profile of the same facing the odd anterior ambulacrum.
All figures are natural size.

Bonin Ids., Captains Ringgold and Eodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

:.\lPacific Ex 1899-1900.

COLOBOCENTROTirS PLATE 37

1 ,

B.Meisel liLh,

Plate 38.

Plate 38.
1-3. ColobocentrotuB Stimpsoni A. Ag.

1. The same as the specimen figured on Plate 37, seen from the actiual side, denuded of

its spines, measuring 65 mm. in diameter.

2. The same seen from the abactinal side.

3. Profile of the same, facing the odd anterior ambulacrum.
All figures are natural size.

Bonin Ids., Captains Ringgold and Eodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

'Albatross'

■ Ex 1899-1900.

COLOBOGENTROTUS PLA.TE 38.

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Plate 39.

Plate 39.

1-2. Colobocentrotus Mertensii Brandt.

1. Showing the right posterior ambulacrum, with the right posterior interambulacrum,

and a part of the right anterior ambulacrum. *

2. Showing the odd posterior interambulacrum with the bivium, and half of the right

posterior ambulacrum.

3-4. Colobocentrotus Stimpsonl A. Ag.

3. The right posterior interambulacrum, with the right posterior ambulacrum and a part

of the right anterior ambulacrum.

4. The right anterior interambulacrum, with the right anterior ambulacrum and a part of

the odd anterior ambulacrum.

1-2 are from a specimen of 70 mm. in diameter, and 3-4 from a specimen measuring
88 mm. in diameter, including the spines. The dotted lines join the radioles of the same
vertical row.

Boniu Ids., N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

"Albatross' Tropical Pacfic Ex 1899-1900,

GOLOBOCENTROTUS PLATE 39.

A.M.V/eiiii^r^'er' gl!

B.Meisel 1

Plate 40.

Plate 40

1-32. Colobocentrotua Stimpsoni A. Ag.
1-32. Spines.

1. Spine, from the buccal membrane close to the teeth.

2. Spine, from the actinal system.

3. 1 Spine, lower side, midway between the actinal system and the ambitus.

4. i Spine, profile of same as 3.

5. Spine, lower side, from the actinal side of tlie ambitus, from the left anterior

ambulacrum.
6.1 Spine, upper side.
7. I Spine, lower side, from the actinal side near the ambitus, from the left anterior

ambulacrum.
Spine, profile.
Spine, upper side.
Spine, lower side, at the ambitus, from the right posterior ambulacrum. These larger

radioles vary in length from 12 to 15 mm.
Spine, profile.
Spine, upper side.
Spine, lower side, from the abactiual side, near the ambitus, from the left anterior

ambulacrum.
Spine, profile.
Spine, upper side.
Spine, lower side, from the abactinal side near the ambitus, from the left posterior

iuterambulacrum.
Spine, profile.
Spine, top view.
Spine, lower side, midway between the ambitus and the abactinal system, from the

odd anterior ambulacrum.
Spine, profile.

9.

10.

11-
12.

13.

14..

15.

16.

17-.
18.-
19.

20..
21.1
22

Spine, top view.

Spine, lower side, from the abactinal side towards the ambitus, from the left posterior
ambulacrum.
23. J Spine, profile.

24. ■> Spine, upper side, from the upper extremity of the left anterior ambulacrum.

25. ) Spine, lower side from the upper extremity of the left anterior ambulacrum.

26. ) Spine, top view, from the upper extremity of the right posterior intei-ambulacrum.

J. ) opine,
r. ) Spine,

27. ) Spine, lower side from the upper extremity of the right posterior interambulaerum.

28. Miliary spine, near the upper extremity of the right posterior interambulacrum, —

hidden by the primary radioles.

29. Miliary spine, lower side, from the anal system.

30. Miliary spine, lower side, from the anal system.

31. 1 Miliary spine, upper side, from the anal system.

32. ) Miliary spine, profile, from the anal system.

The figures are from the same specimen, measuring 88 mm. in diameter.
All the figures are about equally enlarged, except the shaded figures 1, 2, 5, 28, which
are considerably enlarged, as is shown by the adjoining outlines.
Bonin Ids., Dr. Wm. Stimpson Coll.

Albatross" Tropical Pacific Ex 1899-1900.

COLOBOCENTROTUS, PLATE 40,

31 32

3 4

21

30

9

22

23

26

27

10

29

24 25

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12

13

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20

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Plate 41.

Plate 41.
1-7. ColobocentrotUB Stimpsoni A. Ag.

1. The left anterior interambulacrum.

2. The ninth and tenth plates from the actinal system of the left anterior interambu-

lacrum.

3. Showing the large tubercle of the fifth plate from the actinal system, at the ambitus of

the left posterior interambulacrum.

4. The same, seen in profile.

5. One of the primary interambulaeral tubercles on the abactinal side.

6. Grouping of the miliaries on the actinal side of the right posterior interambulacrum.

7. Genital plate and pore of the left anterior interambulacrum.

All the figures are from the same specimen, measuring 88 mm. in diameter, including the
spines.

lionin Ids., Captains Ringgold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpsou Coll.

.cATROSs' Tropicai. Pacific Ex 1899-1900.

COLOBOCENTRC^'.'

41

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Plate 42.

Plate 42.

1-8. Colobocentrotua Stimpaoni A. Ag.

1. Interior view of the actinal side.

2. One of the pairs of perforated plates of the buccal membrane, facing the odd anterior

ambulacrum.

3. Exterior view of the odd anterior ambulacral plates adjoining the actinal system.

4. The same seen from the interior of the test.

5. The tenth plate from the actinal system of the odd anterior ambulacrum.

6. The same seen from the interior.

7. Interior view of a plate of the right posterior ambulacrum at the ambitus.

8. The ocular plate and the abactinal extremity of the left posterior ambulacrum, seen

from the interior.
In figures 3, 4, and 5, 6, a small cross shows the slanting perforation of the pore through

the test.
From a specimen measuring 88 mm. in diameter including the spines.
Boniu Ids., Captains Riuggold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

' Albatr:

GOLOBOGENTROTUS PLATE 4£.

A.MVfesleigren(iel

IMeisellHh

Plate 43.

Plate 43.
1-7. Colobocentrotus Stimpsoni A. Ag.

1. The abactinal system, before being denuded of its spines.

2. The abactinal system of the same, denuded.

3. The same, seen from the interior of the test.

4. The auricles of the right posterior ambulacrum, seen from the interior of the test.

5. The auricles as seen looking towards the actinostome through the auricular opening of

the left posterior ambulacrum.

6. Plates of the right anterior interambulacrum adjoining the actiual system, seen from

the interior of the test.

7. Plates of the odd posterior interambulacrum bordering on the actinal system.
Figs. 6, 7, seem to show the remnant of the arabulacral primordial plates.
From a specimen measuring 88 mm. in diameter including the spines.

Benin Ids., Captains Einggold and Rodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

GoLOBOCF'r™"— ■ Plate 43.

v^ ,

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B.Meisel lith

Plate 44.

Plate 44.

1-12. Colobocentrotus Stimpsonl A. Ag.

1. Lantern seen from above.

2. The same as 1, seen in profile.

3. One of the pyramids, seen from the exterior.

4. The same as 3, seen from the interior.

5. The same, seen in profile.

6. The same, seen from above.

7. a. Epiphysis of pyramid, from the interior, b. pyramid, in profile, from the interior.

8. a. Epiphysis of pyramid, from the exterior, b. pyramid, in profile, from the exterior.

9. Edge of the corrugated surface of pyramid somewhat more enlarged.

10. a. Groove of tooth, b. tooth seen in profile.

11. a. The brace, seen from above, b. seen in profile, c. from below, d. endwise.

12. a. Compass seen in profile, b. seen from above.

All the figures from a denuded specimen 65 mm. in diameter.

Bonin Ids., Captains Ringgold and Rodgers, N. P. Ex. Ex., Dr. Wra. Stimpson Coll.

L,BATR035" TROPrCA'

GOLOBOCENTROTUS PLATE 44.

ib

^^

AM WeslcrgreR del

B Meisnl li'h

Plate 45.

Plate 45.
1-6. Colobocentrotua Stimpaoni A. Ag.

1. The disk of an actinal pedicel.

2. The basal part of one of its laminje.

3. Part of a typical spicule.

4. A deformed spicule.

5. Fragment of a deformed spicule.

6-10. Colobocentrotua Mertenaii Brandt.

6. Fragment of a spicule.

7. Basal part of a lamina.

8. Shows the quadratic arrangement of the spicules.

9. Typically formed spicule.

10. Top of a pedicel, taken from the abactinal side and hidden by the large radicles.

Figures 1-5 are from a specimen, 88 mm. in diameter including the spines and those
of 6-10 from an individual, measuring 70 mm. in diameter.

Bonin Ids., Captains Ringgold and Eodgers, N. P. Ex. Ex., Dr. Wm. Stimpson Coll.

'Albatross' Trl

-re Ex. 1899 -i900.

COLOBOCENTROTUS PLATE 45.

^^m^-^

-^%H4.,

10

A.N'.Wes'ia^rEr- afl

B.Meisel liih.

Plate 46.

Plate 46.

1-4. Fodophora pedifera Agass.

1. The odd anterior ambulacrum of a denuded specimen 55 mm. in diameter.

2. Pore near the actinal system, from the same specimen.

3. Pore at the ambitus.

4. One of the pores of the ninth plate from the actinal system.

5-8. Fodophora atrata Agass.

5. The odd anterior ambulacrum of a denuded specimen 46 ram. in diameter.

6. Pore near the actinal system, corresponding to the pore of fig. 5.

7. Pore at the ambitus.

8. One of tlie pores of the eighth plate from the actinal system.

9-12. Colobocentrotus Stimpsoni A. Ag.

9. The odd anterior ambulacrum, of a denuded specimen 65 mm. in diameter.

10. Pore near the actinal system corresponding to the pore of fig. 5.

11. Pore at the ambitus.

12. One of the pores of the eleventh plate from the actinal system.

"Albatross" Tf.opical Pacific Ex 1899-1900

Ck)LOBOCENTROTUS PLATE 46.

®

7 (Q)

& 'I

JO

AMWestergrendel

B Meisel lith.

The following Publications of the Museum contain Beports on the Dredging Operations in
charge of Alexander Agassiz, of the U. S. Fish Commission Steamer ''Albatross," during
1891, Lieut. Commander Z. L. Tanner, U. S. K, Commanding.

Three Letters from Alexander Agassiz to the Hon.
Marshall McDonald, U. S. Commissioner
of Fish and Fisheries, on the Dredging
Operations of the "Albatross" in 1891.
BuU. M. C. Z., Vol. XXI. No. 4. June,
1891. 16 pp.
I. A. Agassiz. On Calamocrinus Diomedse, a
new Stalked Crinoid from the Galapa-
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III. A. Goes. Neusina Agassizi. Bull. M. C.Z.,

Vol. XXIII. No. 5. December, 1892.
4 pp. 1 Plate.

IV. H. LuDwiG. t^orliiufiger Bericht iiber die

erbeuteten Holothurien. Zeit. Anz., No.

420. 1893. Bull. M. C. Z., Vol. XXIV.

No. 4. June, 1893. 10 pp.
V. Geo. p. Merrill. The Rocks of the

Galapagos. Bull. M. C. Z., Vol. XVI.

No. 13. July, 1893. 3 pp.
VI. W. Faxon. Preliminary Descriptions of

new Species of Crustacea. Bull. M. C. Z.,

Vol. XXIV. No. 7. August, 1893. 72 pp.
VII. S. H. ScuDDER. The Orthoptera of the

Galapagos. Bull. M. C. Z., Vol. XXV.

No. 1. September, 1893. 25 pp. 3 Plates.
VIII. W. ScHiMK^wiTscH. The Pygnogonidae.

Bull. M. C. Z., Vol. XXV. No. 2. Decem-
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IX. W. McM. WooDWORTH. The Planari-

ans. Bull. M. C. Z., Vol. XXV. No. 4.

January, 1894. 4 pp. 1 Plate.
X. Th. Studkr. Note pr^liminaire sur les

Alcyonaires. Bull. M. C. Z., Vol. XXV.

No. 5. February, 1894. 17 pp.
XI. S. F. Clarke. The Hydroids. Bull.

M. C. Z., Vol. XXV. No. 6. February,

1894. 7 pp. 5 Plates.
XII. H. LuDwiG. The Holothurians. Mem.

M. C. Z., Vol. XVII. No. 3. October

1894. 183 pp. 19 Plates.

XIII. R. Bergh. Die Opisthobranchien. Bull. M.

C. Z., Vol. XXV. No. 10. October, 1894.
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XIV. A. Ortmann. The Pelagic Schizopoda.

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XV. W. Faxon. The Crustacea. Mem. M. C. Z.,
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XVI. W. Giesbrecht. Die Pelagischen Cope-

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XVII. C. H. TowNSEND.' The Birds of Cocos

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XVIII. C. Hartlaub. Die Comatuliden. Bull.

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XIX. G. W. MuLLER. Die Ostracoden. Bull.
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1896. 103 pp. 9 Plates.
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1897. 38 pp. 6 Plates.

XXm. A. Agassiz. Preliminary Report on the

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No. 5. June, 1898. 18 pp. 14 Plates.
XXrV. E. L. Mark. Preliminary Report on

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C. Z., Vol. XXXII. No. 8. August,

1898. 8 pp. 3 Plates.

XXV. C. F. Li^TKEN and Th. Mortensen. The
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XXVI. S. Garman. The Fishes. Mem. M. C. Z.,
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XXVII. W. McM. WooDWORTH. Preliminary
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XXVIII. L. Stejneger. Two new Lizards of the
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XXIX. W. E. HoYLE. The Cephalopoda. BuU.
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1904. 71 pp. 12 Plates.

XXX. H. V. Wilson. The Sponges. Mem. M.
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XXXI. R. VON Lendenpeld. The Radiating
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1905. 49 pp. 11 Plates, 1 Chart.
XXXII. A. Agassiz. The Panamic Deep Sea

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XXXni. E. VON Marenzeller. Stein-und
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XXXIV. E. von Marenzeller. Lagisca Irritans,

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XXXV. H. LuDwiG. Asteroidea. Mem. M. C. Z.,

Vol. XXXII. July, 1905. 12, 292 pp.
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XXXVI. E. Trojan. Ein Beitrag zur Morpholo-

gic des Tiefseefischgehirues. Mem.
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1906. 42 pp. 6 Plates.
XXX^^I. W. H. Dall. The MoUusca and the

Brachiopoda. Bull. M. C. Z., Vol.
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