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THE 



PALEONTOGEAPHICAL SOCIETY. 



INSTITUTED MDCCCXLVII. 



LONDON 

MDCCCXCI — MDCCCCVIII. 



MONOGRAPH OF THE BRITISH FOSSIL ECHINODBRMATA FROM 
THE CRETACEOUS FORMATIONS. 

Vol. II. — AsTEROiDEA AND Ophiueoidea. 



Mr. Sladen is the author of jjages 1 — 66, Phites I — XVI, while Mr. Spencer 
is the author of the remainder of the Voh;me. ]\Ir. Spencer desires to express 
his indebtedness to Dr. F. A. Bather for much help and advice in his share of 
the work. 



ORDER OF BINDING AND DATES OF PUBLICATION. 



PAGES 


PLATES 


ISSUED IN VOL. 
FOR TEAR 


PUBLISHED 


Title-page 






1908 t 


December, 1908 


1—28 




I— VIII 


1890 ' 


April, I89I 


29— (J6 




IX— XVI 


1893 


December, 1893 


67—90 




XVII— XXVI 


1905 


November, 1905 


91—132 




XXVII— XXIX 


1907 


December, 1907 


133—138 (including 


Index) 


— 


1908 


December, 1908 



The Plates are intended to be collected and bound at the end of the Volume. 



^^ 



A jroXOOUAPH 



ON THE 



B E I J I S H F () S S T T. 



ECHINODERMATA 



FROM 



Tin: CliETACEOUS FUiiMATlONS. 

VOLUME SECOND. 
THE ASTEEOIDEA AND OPHIUEOIDEA. 

BY 

W. PERCY SLADEN, F.L.S., F.G.S., 

AND 

^Y. K. SPENCER, B.A., F.G.S. 






L O N D O N : 
PRINTED FOK THE PAL^ONTOGE APHICAL SOCIETY. 

1891—1908. 




\^^:^\l 



N 



t.-.. 



PRINTED BT ADLABD AND SON, LONDON AND DORKING. 



THE 



PAL.EONTOGRxirinCAL SOCIETY. 



INSTITUTED MDCCCXLVII. 



VOLUME FOli 1890. 



LONDON 



nv^ff-7,J A MOJLOGRAPH 



OK THE 



BRITISH FOSSIL 



ECHINODERMATA 



PROM 



THE CRETACEOUS FORMATIONS. 

VOLUME SECOND. 
THE ASTEBOIDEA. 

BY 

W. PERCY SLADEN, F.L.S., F.G.S.. &c., 

8ECKETABV OF THE LINNEAN SOCIETY. 



PART FIRST. 

Pages 1—28 ; Plates I— VIII. 



LONDON: 
PRINTED FOR THE PAL^ONTOGRAPHICAL SOCIBTr. 

1891. 



PHINTKD BT 
ADLA.BD AND SON, BAETHDI.OMEW CLOSE. 



A MONOGRAPH 



ON THE 



FOSSIL ECHINODERMATA 



OP THE 



CRETACEOUS FOEMATIONS. 



THE ASTEROIDEA. 



INTRODUCTORY REMARKS. 

It was the intention of the late Dr. Thomas Wright to have continued his 
magnificent series of Monographs on the British Fossil Echinodermata of the 
Oolitic and Cretaceous Formations, which have already appeared in the volumes of 
the Paloeoutographical Society, by the publication of a Monograph on the Creta- 
ceous Asteroidea. "With this object in view a number of plates had been prepared 
under Dr. Wright's directions, and some preparatory notes for the letterpress had 
been written, when the work was cut short by the lamented death of the author. 
Subsequently the Council of the Palaeontographical Society did me the honour of 
inviting me to undertake the memoir. The plates and notes above mentioned 
were placed at my disposal, but tiie latter proved to be for the main part merely 
summaries or transcripts of descrijjtions already published, and were unfortunately 
unsuitable to form part of the letterpress. For the whole of the latter I am 

1 



2 FOSSIL ASTEROIDEA. 

therefore responsible. The plates which were drawn on stone have all been 
utilised, although the specimens illustrated were not in every case those which I 
should have selected, nor the order in which the figures are associated on some of 
the plates that which I should have followed. This, however, is a comparatively- 
small matter, and the remark is not intended in any way as disparaging the 
excellence of the illustrations. Indeed, I would here bear unqualified testimony 
to the careful and accurate way in which the fossils have been dehneated by 
Mr. A. H. Searle. His plates are monuments of patient study of morphological 
detail, and of exquisite technical execution as examples of lithographic drawing. 

In his Monograph on the Oolitic Asteroidea, Dr. Wright gave as an intro- 
duction a general account of the structure of the main divisions of the Asteroidea 
then known, recent as well as fossil, with special reference to the calcareous 
framework ; and he also gave a summary of the difi"erent systems of classification 
which had been formulated by previous writers on the subject. It would there- 
fore, in my opinion, be out of place, and in a certain measure superfluous, to preface 
the present memoir with a similar introduction ; but, as the knowledge of recent 
Starfishes has been considerably extended since the date of Dr. Wright's contribu- 
tion, I propose to give in an appendix to this monograph my views on the classi- 
fication of the Asteroidea, with special reference to the fossil forms. 

At the commencement of his splendid Monograph on the Cretaceous 
Echinoidea — to which the present memoir is a sequel — Dr. Wright gave a valuable 
stratigraphical summary of the Cretaceous Formations in Britain. It is conse- 
quently altogether needless to burden the pages of the Society's publications with 
a repetition of these details. I shall, however, if necessary on the completion of 
my work, giv^ a synopsis of the distribution in time of the various species dealt 
with, together with such remarks on their occurrence and associations as occasion 
may require. 



FOSSIL ASTEROIDEA. 



DESCRIPTION OF THE CRETACEOUS SPECIES. 



S«i-c?ass— EUASTEROIDEA, Sladen, 1886. 

Or(ie?-— PHANEROZONIA, Sladen, 1886. 

FiTwtVy— PENTAGONASTERID^, Perrier, 1884. 

Phanerozonate Asterids, with thick and massive marginal plates, which may 
be either naked, or bear granules or spiniform papillae. Disk largely developed. 
Apical plates often increscent. Abactinal surface tessellate, with rounded, poly- 
gonal or stellate plates, which may be tabulate or paxilliform. Actinal inter- 
radial areas largely developed, covered with pavement-like plates, which may be 
naked or covered with membrane, or may bear granules or spinelets. 

The family Pentagonasteridae, as defined by Prof. Edmond Perrier' in 1884, 
was separated from a larger and more comprehensive group of genera which had 
been previously recognised by him* as constituting the family Gouiasteridas. The 
name Goniasteridae was not retained for any of the groups or families into which 
that incongruous series of genera was divided. Previous to 1875, even the generic 
name of Goniaster had been very loosely and incorrectly applied. The vaguest 
notions as to the limits or characters of the genus seem to have been held. The 
mere form of the body, and the applicability of the significant name, irrespective 
of structural details, appear to have alone determined the reference of a large 
number of the species which have at different times borne the generic name of 
Ooniaster. 

1 ' Nouv. Archives Mub. Hist. Nat.,' 2e s^rie, 1884, t. vi, p. ICi. 

' 'E^vis. Stell. Mub.,' p. 25 ('Archives de Zool. exper.,' 1875, t. iv, p. 289). 



4 FOSSIL ASTEROIDEA. 

M. Perrier showed that none of the recent species ranked as Goniaster pre- 
vious to 1875 had any right to be so called. He consequently employed the name 
in a new and restricted sense, taking the Astcrias obtusangula of Lamarck as the 
type of the genus. No other species is at present known which can be regarded 
as congeneric with that form. 

A large number of fossil Starfishes have been named as species of Goniaster, 
but none of them present characters which justify their reference to that genus 
in its new sense, and none of them invalidate the course taken by Prof. Perrier. 
It will therefore be unnecessary in the following pages to discuss in each case 
separately the reasons for removing the large number of species which have 
from time to time been ranked under the name of Goniaster. 



Subfamily — PentagonasteriNvE, Bladen. 

Pentagonasteein^, Sladen. Zool. Chall. Exped., part li, Eeport on the Aste- 

roidea, 1889, pp. xxxi, 262. 

Pentagonasterid?e with the abactinal area paved with rounded, polygonal, or 
paxilhform plates. Granules or spinelets when present co-ordinated. 



G^emis— CALLIDERMA, Gray, 1847. 

Callideema, Gray. Proc. Zool. Soe. Lend., part xv, 1847, p. 76 ; Ann. and Mag. 
Nat. Hist., 1847, vol. xx, p. 198; Synop. Spec. Start'. 
Brit. Mus., 1866, p. 7. 

Marginal contour stellato-pentagonal. General form depressed. Disk large 
and flat. Rays moderately elongated and tapering. Marginal plates forming a 
broad border to the disk, and may be united along the median abactinal line of 
the ray throughout [or, in some fossil species, may be separated by one or more 
series of medio-radial plates, at least at the base of the ray]. The marginal 
plates of both series are granulated. [In recent species the supero-marginal 
plates bear some small papilliform spinelets on the margin where the abactinal 
and lateral surfaces of the plate unite ; and the infero-marginal plates have a 
number of similar, but larger and more fully developed, spinelets irregularly dis- 
tributed amongst the granulation of the actinal surface.] Abactinal area of the 
disk covered with small and regularly arranged plates, hexagonal in the radial 
areas, bearing co-ordinated granules, and some with a larger, globular, central, 



CALLIDERMA. 5 

tubercle-like granule. Actinal interradial areas large, confined to the disk. 
Actinal intermediate jdates large, covered with granules [and in the recent species 
bearing one or occasionally two compressed acute papilliform spinelets]. Arma- 
ture of the adambulacral plates arranged in longitudinal series. 

This genus was established by Dr. J. E. Gray for the reception of a recent 
Starfish, the type of which is preserved in the British Museum. It was described 
under the name of Gall'ulerma Emma. In his remarks which follow the diagnosis, 
Dr. Gray observes' that "there is a fossil species, very like the one hero 
described, found in the chalk, and figured in Mr. Dixon's work on the fossils of 
Worthing, which I propose to call Galliderma Dixonii." I have not been able to 
trace which of the fossil species is here referred to, but that is a circumstance of 
no great importance, as the forms figured in Mr. Dixon's work on ' The Geology 
of Sussex ' were described and named by the late Prof. Edward Forbes. It is inter- 
esting, however, to note that the resemblance of some of the Cretaceous forms to 
the genus CaUideruia had actually been observed by the author of that genus. 

Thanks to the careful study and critical insight of Mr. J. Walter Gregory, of 
the British Museum, a number of the examples which now form part of the 
National Collection have been correctly, as I think, referred to the genus Calli- 
derma, and already bear that name upon the manuscript labels attached by him to 
the specimens. 

There are, however, some differences between the fossil forms and the recent 
type. The most notable perhaps being the character presented by the spinulation 
of the marginal, the abactinal, and the actinal intermediate plates in the recent 
species, as compared with the fossil examples, whose state of preservation does not 
permit of our positively asserting whether the same character was present in their 
case or not. I am inclined to think that this uncertainty does not necessarily 
invalidate the reference of the fossil forms to the genus, and I consider it highly 
probable that species might exist which did not bear incipient spinelets on the 
plates in which they are found in the solitary existing species with which we are 
acquainted. The peculiar pits found upon the plates in some of the fossil examples 
may indicate the former presence of these spinelets, although, for my own part, I 
am more disposed to believe that in the majority of cases the depressions in 
question are structures associated with a pedicellarian apparatus. (See, for ex- 
ample, PI. I, figs. la,\h, 1 c, 1 d; PI. Ill, fig. 3a; PI. V, figs. 2a, 2l>, 2d.) 
In other cases it is certain that little spinelets did exist, as in the tip of the ray 
shown in PI. VIII, fig. 2 a ; also, but perhaps more doubtfully, in PI. VII, figs. 
4 a, 4 c. 

' ' Proc. Zool. Soc. Lond.,' [lart xv, 1847, p. 7G ; 'Syuop. Spi-c. Starf. Brit. Mub.,' London, 
18G0, p. 7. 



6 FOSSIL ASTEROIDEA. 

Another point of difference is to be found in some of the fossil forms which are 
referred in the following pages to the genus Galliderma ; and this consists in the 
separation of the supero-margiual plates, at least at the base of the ray, by one or 
more series of medio-radial plates. It is a character whose importance is not to be 
under-estimated, but too little as yet is known of the morphological plasticity of 
the genus to justify in my opinion the separation of the forms on this ground 
alone. I prefer, therefore, to regard this extension of the abactinal plating as a 
transitional character, and I believe that this opinion is warranted by the range of 
plasticity observed in other genera of recent Asteroidea. 



1. Calltdeema SMiTHiiE, Forhes, sp. PI. I, figs. 1 a — 1/; PI. VIII, figs, 2 a — 2 c. 

GoNiASTEE (A.STEOG0KIUM) Smithii, Forbes, 1848. Memoirs of the Geological 

Survey of Great Britain, vol. ii, 
p. 474. 

— — — — 1850. In Dixon's Geology and 

Fossils of the Tertiary and Cre- 
taceous Formations of Sussex, 
London, 4to., p. 334, pi. xxii, 
figs. 1 and 2. 

— — Smithi.5;, Morris, 1854. Catalogue of British Fossils, 

2nd ed., p. 80. 
AsTEOGONim Smithii, Dujar din and IIuj)€, 1H62. Hist. Nat. Zooph. 

Echin. (Suites a Bufi"on), p. 399. 
GoKiASTEE Smithi, Quensfedt, 1876. Petref'actenkunde Deutsch- 

lands, I. Abtbl., Bd. iv, p. 64. 

— (Asteogoniiim) SsiiTHi.a;, Forbes, 1878. In Dixon's Geology of Sussex 

(new edition, Jones), p. 367, 
pi. XXV, figs. 1, 2, 2 a. 

Body of large size. General form depressed. Abactinal area probably capable 
of slight inflation, and more or less flexible : a slight carination being present in 
the radial abactinal regions. Actinal surface flat. Marginal contour stellato- 
pentagonal, the major radius measuring rather more than twice the minor radius. 
Rays broad at the base and tapering gradually to the extremity. Interbrachial 
arcs well rounded and forming a regular curve. Margin thick, with a well-defined 
channel traversing the line of junction of the supero-marginal and infero-marginal 
series of plates, formed by the tumid character of the marginal surface of both 
series of plates. 

The infero-marginal plates are about twenty or twenty-one in number, counting 



CALLIDERMA. SMITHI^. 7 

from the median interradial line to the extremity. They form a broad conspicuous 
border to the actinal area, the breadth of which diminishes gradually from the 
median interradial line to the extremity. The largest infero-marginal plates near 
the median interradial line measure 9 mm. in breadth, and 4 mm. in length ; the 
length increases a little between this point and the base of the ray, where it is 
again 4 mm. The breadth decreases step by step from the median interradial line, 
and at the base of the ray is less than 4 mm., and further out the breadth of the 
plates is less than the length. The height of the infero-marginal plates as seen in 
the margin is greater than the length of the plate, the proportions near the 
median interradial line being as 3 : 2 approximately. The proportion of the 
height decreases at the extremity of the ray. The infero-marginal plates are 
slightly convex on their actinal surface and distinctly tumid on their marginal 
surface. The whole superficies is covered with small, hexagonal, closely-placed 
punctations, upon which granules were previously borne, probably uniform in size 
and compactly placed. On a number of the plates are one or more subcircular or 
irregular shallow concavities, quite irregular in size, position, and occurrence, 
which I believe to have been caused by the presence of a pedicellarian apparatus, 
perhaps the cavities of ordinary foraminate pedicellarise enlarged by weathering. 
These are seen in PI. I, figs. 1 a, 1 b, 1 c, 1 d. I scarcely think that they are the 
marks left by tubercles or enlarged granules. In the example, however, figured 
on PI. VIII, fig. 2 (/, small spinelets were undoubtedly present. 

The adambulacral plates are broader than long, their dimensions at a short 
distance from the mouth being 3*25 mm. broad and 1"75 mm. long. They bear 
upon their surface four or five ridges, parallel or sub-parallel to the ambu- 
lacral furrow, each with five or six articulatory elevations upon which spines had 
previously been borne. A number of these spines are still preserved, irregularly 
strewed over the surface of the plates. They are short, tolerably robust, slightly 
flattened, slightly tapering and abruptly rounded at the tip. The longest 
measures about 1"5 mm. in length, or a little more; their surface is finely striate, 
in fact so fine that the character is perhaps mainly due to the effect of weathering 
upon the structural texture of the spine. 

The actinal interradial areas are large and are covered with a great number of 
small, regular, quadrangular or rhomboid intermediate plates, which are arranged 
in series parallel to the ambulacral furrow, and form a compact tessellated pave- 
ment. The average size of the plates is about 2 mm. in diameter, but the plates 
of the series adjacent to the adambulacral plates are somewhat broader, and the 
plates near to the infero-marginal plates become smaller and irregular. The plates 
extend at the base of the ray to about the eighth infero-marginal plate, counting 
from the median interradial line. The surface of the plates is covered with large, 
rather widely spaced, hexagonal punctations — the marking left by the granules 



8 FOSSIL ASTEROIDEA. 

previously borne upon the plates, which appear to have been rather large and 
uniform. 

Very few, if any, pedicallarife appear to have been borne on the actinal inter- 
mediate plates. 

The character of the mouth-plates and their armature cannot be made out in 
any of the examples I have examined. 

The supero-marginal plates are only exposed in the marginal view of the 
example under description. Their height is seen to be less than that of the 
infero -marginal plates, and they are also rather smaller both in length and breadth ; 
about twenty-two appear to be present between the median interradial line and the 
extremity of the ray. In their general character and ornamentation they resemble 
closely those of the infero-marginal series. 

From another example, also contained in the British-Museum Collection, and 
bearing the registration mark " E. 2037," in which the abactinal surface is shown, 
the following details are supplemented. 

The abactinal area is covered with small, regular, hexagonal plates or paxillar 
tabula, which are slightly rounded superficially, and a little bevelled on the 
margin of the tabulum. The surface of the tabulum is covered with punctations 
or marks left by the granules originally borne on the plate, and here and there 
small pedicellarian foramina may be seen, usually near the margin of the plate. 
The plates (or paxillge) of the median radial series are broader than any of the 
others, the largest measuring about 2 mm. in breadth, and a little more than 1 
mm. in length. The other tabula are true hexagons, measuring about 1 mm. in 
diameter or a trifle more, and they are arranged in longitudinal series parallel to 
the median radial series. Eight or nine series are present on each side of the 
median radial series on the disk. Opposite the eighth supero-marginal plate, 
counting from the median interradial line, only the median radial series and one 
lateral series of tabula on each side of it are present. The median radial series 
then extends alone and is present at the fourteenth plate, where the ray is broken 
in the example under description — and looks like continuing further — pro- 
bably reaching to the extremity of the ray. 

Dimensions. — In the type specimen (figured on PI. I) the major radius is 
98 mm., the minor radius 48 mm., the thickness of the margin from 9 to 10 mm. 
The breadth of a ray between the fifth and sixth infero-marginal plates measures 
about 28 mm. 

Locality/ arid Strat.igraphical Portion. — The specimen figured on PI. I is from 
the Lower or Grey Chalk at Burham, in Kent. The species has also been ob- 
tained from the Upper Chalk at Brighton (Coll. Brit. Mus.) ; and it is sometimes 



CALLIDERMA iMOSAICUM. 9 

found in ferric sulphide at Amberley Pit, Sussex. The fragment figured on 
PI. VIII, figs. 2 rt, 2 b, 2 c, is from the Lower Chalk of Dover. 

History. — The type specimen, from which this species was originally described 
by the late Edward Forbes in 1848, formed part of the collection of Mrs. Smith, of 
Tunbridge Wells. It is now preserved in the British Museum. It was first 
figured in Dixon's ' Geology and Fossils of the Tertiary and Cretaceous Forma- 
tions of Sussex,' London, 1850. PI. I of the present memoir is a faithful draw- 
ing of the same beautiful specimen. 



2. Calliderma mosaicum, Forbes, sp. PI. V, figs. 2 a— 2 e; PI. VI, figs. 1 and 2 

a,b,c; PL VII, figs. 4 a, b, c. 

GoNiASTEE (Astbogonium) M0SAICU8, Forbcs, 1848. Memoirs of the Geological 

Survey of Great Britain, vol. ii, 
p. -175. 

— — MOSAictJS, Forbes, 1850. In Dixon's Geology and 

Fossils of the Tertiary and Cre- 
taceous Formations of Sussex, 
London, 4to., p, 334, pi. xxiv, 
fig. 26. 

— — MOSAicus, J/brn«, 1854. Catalogue of British Fossils, 

2ud ed., p. 80. 
AsTBoaoNiUM MOSAICUM, Dujardirt and Hupe, 1862. Hist. Nat. 

Zoojih. Echin. (Suites a Buffon), 

p. 399. 
GoKiASTEB (Astbogonium) mosai'cus, JbrJc«, 1878. In Dixon's Geology of Sussex, 

(new edition, Jones), p. 367, 

pi. xxvii, fig. 26. 
GoHiASTEE M08AICU3, Etheridge, 1885. In Phillips's Manual of 

Geology (new edition), part ii, 

by E. Etheridge, p. 560. 

Body of large size. Disk large. Rays narrow at the base and well produced. 
General form depressed and thin. Abactinal area proliably capable of slight 
inflation, and more or less flexible ; some carination present in the radial abactinal 
regions. Actinal surface flat. Marginal contour stellato-pentagonal, the major 
radius measuring more than twice and a half the minor radius. Rays narrow, 
the supero-marginal plates being united in the median radial line. Interbrachial 
arcs wide and with their curvature more or less flattened, which gives a distinctly 
pentagonal character to the disk. Margin rather thin, and with the latei-al wall 
perpendicular. 

2 



10 FOSSIL ASTEROID EA. 

The supero-marginal plates are about twenty-eight in number, counting from 
the median interradial line to the extremity. (This number is taken from the 
fragment figured on PI. VII, fig. 4 a ; in the larger example drawn on PI. V, 
fig. 2 a, twenty-two may be counted up to the place where the ray is broken.) 
They form a well-defined, conspicuous border, but the breadth of this is distinctly 
less in proportion to the size of the disk when compared with the breadth of the 
marginal plates in Galliderma Smithise. The largest supero-marginal plates in the 
specimen figured on PI. V, fig. 2 «,near the median interradial line, measure 5*25 mm. 
in breadth and 3"25 mm. in length. The breadth diminishes very slightly as 
the plates approach the base of the ray, but from that part outward the length of 
the plates becomes much reduced — the breadth remaining the greater dimension 
throughout the ray. 

The supero-marginal plates are comparatively flat on the abactinal surface and 
only slightly depressed along their margins of juncture. The general surface of 
the whole series has the character of sloping at a small angle to the margin of the 
disk, to which it gives a slightly bevelled appearance. The marginal surface of 
the plate is almost vertical, the junction of the abactinal and marginal surfaces is 
well rounded but not tumid, and there is very slight, if any, convexity on the 
marginal surface, at least along the disk. The height of the plates as seen in the 
margin is only a little greater than the length, and the diminution in height is 
only very trifling as the plates proceed along the ray. The whole superficies of 
the plates is covered with small hexagonal punctations upon which granules were 
previously borne, Small foraminate pedicellarite are occasionally present here 
and there upon the plates ; the foramen is small and oval, and is surrounded by a 
definite margin or lip. Sometimes more than one are present on one plate. 
The example figured on PL VII, fig. 4 a, is remarkable for the presence of the 
prominent teat-like eminences, in the centre of which the pedicellarian foramen is 
situated. These eminences at first sight look like tubercles for the articulation of 
spines (see PI. VII, figs. 4 a, 4 c). A similar character is also seen in the example 
drawn on PI. V, fig. 2 a, but is less strongly marked (see fig. 2 d). 

The abactinal area of the disk is covered with small, regular, hexagonal and 
tetragonal plates or paxillar tabula ; those in the radial areas being regularly 
hexagonal and larger than those in the intermediate regions, which are rhomboid, 
and all diminish in size as they approach the margin. The abactinal plates or 
paxillae do not appear to extend beyond the twelfth supero-marginal plate, counting 
from the median interradial line ; the supero-marginal plates of the two sides of 
the ray meeting in the median radial line beyond this point. The plates or paxillae 
of the median radial series are larger and broader than any of the others ; they 
are succeeded on each side by five or six longitudinal series of hexagonal plates, 
those of the second or third series from the median series measuring about l"5mm. 



CALLIDERMA MOSAICl'M. 11 

in diameter. The remaining plates which occupy the intermediate areas are 
tetragonal or rhomboid. All the plates have their surface marked with rather 
widely-spaced punctations — the impressions of the granules previously present. 
Small foraminate pedicellarijB are also frequently present here and there, usually 
near the margin of the plate. 

The madreporiform body is flat, distinct, and polygonal in outline ; it is situated 
near the centre of the disk. Its surface is marked by fine straight striaj, which 
radiate regularly centrifugally from the centre to the margin (see PI. V, fig. 2 e). 

Other specimens show that the infero-marginal plates in this species are more 
nearly subequal to the supero-marginal series than in Cnlliderma Smithiae, that the 
actinal intermediate plates are relatively larger than in that species and a good 
deal larger than the abactinal paxillar plates or tabula. The actinal intermediate 
plates originally bore granules only, judging from the character of the punctations 
with which their surface is ornamented. A fraorment belonorinof to the British 
Museum Collection (which bears the register number " E 373 "), in which the spines 
that formed the armature of the adambulacral plates are preserved, indicates that 
these spines are smaller, shorter, and perhaps more numerous than in Galliderma 
Smithise. 

In the example drawn on PI. VI, fig. 2 a, the supero-marginal plates are pre- 
served, but the whole of the abactinal plating has been removed, leaving exposed 
the inner surface of some of the actinal intermediate plates and the adambulacral 
plates. Magnified details of these plates are given, and they represent the cha- 
racters of the structures preserved better than any verbal description. 

Dimensions. — The large example figured on PI. V, fig. 2 a, has the following 
measurements : — Major radius 82 + mm. (all the rays are broken and imperfect, 
and the full dimensions cannot therefore be given) ; minor radius 36 mm. ; thick- 
ness of the margin about 8 mm. Breadth of a ray between the eighth and ninth 
supero-marginal plates about 15 mm., or a trifle more. 

Locality and Strafigraphical Position. — The example figured on PI. V, fig. 2 a, 
is labelled from the Lower Chalk, but the locality is not recorded. It formed 
part of one of the old collections preserved in the British Museum. Other 
examples in the British Museum are from the Grey Chalk or Chalk Marl of Dover, 
from the Lower Chalk of Glynde in Sussex, and from the Lower Chalk of 
Amberley Pit, Arundel. There is also a magnificent specimen in the Museum of 
Practical Geology, Jermyn Street, from the Lower Chalk of Dover. 



12 FOSSIL ASTEROIDEA. 



3. Calliderma latum, Forbes, sp. PL II, figs. 1 a — 1 e, 2 a — 2 d ; PI. Ill, 

figs. 1 a — 1 e, 2 a, 2b, S a, B b. 

GoNiASTEE (Asteogonitjm) latus, Forhes, 1848. Memoirs of the Geological 

Survey of Great Britain, vol. ii, 
p. 474. 

— — — — 1850. In Dixon's Geology and 

Possils of the Tertiary and Creta- 
ceous Formations of Sussex, 
London, 4to., p. .333, pi. xxiii, 
figs. 4, 5. 

— — — Morris, 1854. Catalogue of British Fossils, 

2nd ed., p. 80. 
AsTEOGONiTTM LATUM, Dujardin and Hupe, 1862. Hist. Nat. Zooph. 

Echin. (Suites a Buffon), p. 399. 
GoNiASTEE (Asteogonitjm) latus, Forhes, 1878. In Dixon's Geology of Sussex 

(new edition, Jones), p. 367, 

pi. xxvi, figs. 4, 5. 

Body of large or moderate size. General form depressed. Abactinal surface 
probably capable of some degree of inflation. Actinal surface flat. Marginal 
contour stellato-pentagonal, the major radius probably not exceeding the minor 
radius by more than one half. Rays narrow at the base, short, not greatly pro- 
duced, and probably tapered to a pointed extremity. Interbrachial arcs very 
wide and flattened, which gives a strongly marked pentagonal outline to the disk. 
Margin of uniform thickness. 

The infero-marginal plates are more than sixteen in number, counting from the 
median interradial line to the extremity (the tip of the ray being broken in all the 
specimens examined). They form a remarkably broad margin to the actinal area of 
the disk, which diminishes rather rapidly in width at the base of the rays, and then 
slightly to the extremity. The largest infero-marginal plates near the median 
interradial line measure about 13 mm. in breadth and 45 mm. in length. The 
length is nearly uniform throughout, or at any rate till well out on the free part 
of the ray ; but the breadth diminishes until the plates at the base of the ray are 
6*5 mm., and the diminution proceeds to a certain extent along the ray. The 
infero-marginal plates are slightly convex along their line of breadth, by which 
means the separate plates are distinctly marked. They are well rounded at the 
junction of the actinal and lateral surfaces, and are slightly tumid in the margin. 
The outline of their inner or adcentral edge is also rounded. The height of the 



CALLIDERMA LATUM. 13 

infero-marginal plates as seen in the margin is a little greater than their length. 
The height of the supero-marginal plates is, however, somewhat greater. 

The whole superficies of the plates is covered with circular punctations of 
irregular size rather than hexagons, as in the other forms, and the irregularity 
caused by the presence of larger punctations here and there is remarkable. This 
character seems to indicate the former presence of an irregular-sized granulation. 

The supero-marginal plates are similar in character to the infero-marginal 
series, but the large irregular punctations are larger and more numerous. 

The adarabulacral plates are broader than long, and they bear upon their 
surface five or six ridges parallel or subparallel to the arabulacral furrow, each with 
prominent well-defined granulations or elevations, all uniform and closely placed, 
upon which the adambulacral armature of spines was previously borne (see PL II, 
fig. Irf; PI. Ill, fig. 2?>). 

The actinal interradial areas are large, and are covered with comparatively 
large polygonal and rhomboid intermediate plates, which arc arranged in series 
parallel to the ambulacral furrow, and originally formed a compact tessellated 
pavement. In a number of the fossils of this species, however, these plates are 
often separated and displaced, which leads to the inference that in life the plates 
were not so intimately connected as in other species, and that membrane or con- 
nective tissue was more largely developed. The one or more series of plates 
adjacent to the adarabulacral plates are much larger than the others, and none of 
the intermediate plates extend beyond the base of the ray. The surface of the 
plates is covered with large, irregular, and rather deeply sunken pits, the 
character of which leads to the inference that the granulation originally present 
was also somewhat irregular in size and coarse in character (see PI. II, fig. 1 c ; 
PI. Ill, fig. 1 e). 

In some examples (notably in that figured on PL III, fig. 2 a) small oval fora- 
minate pedicellarise, distinctly lipped at the margin of the foramen, are present on 
the actinal intermediate plates. 

The mouth-plates are elongate, about three times as long as broad, triangular 
in shape, with the two outer sides subequal. Their surface is covered with large, 
coarse, irregular, tuberculose elevations (see PL II, fig. 1 e), which suggest the 
inference that the armature of the mouth-plates consisted of large, irregular, 
papilliform granules. 

In some examples a portion of the actinal floor has been removed, exposing the 
inner surface of the abactinal floor. In these cases the stellate base of the abac- 
tinal plates or paxillae are seen (see PL II, figs. 2 a, 2d; PL III, figs. 3 a, 3 b). It 
will be noticed that there is a difference in the form of the stellate bases in these 
examples, which may indicate a specific or varietal difference, but I do not feel 
justified from this character alone in recognising either of these fragments as the 



14 FOSSIL ASTEROIDEA. 

type of a distinct species. More material is needed before such a step would be 
warranted. 

Dimensions. — The large example figured on PI. II, fig. 1 a, has a major radial 
measurement of from 80 to 95 mm. or more, with a minor radius of about 52 mm. 
The breadth of the ray between the sixth and seventh infero-marginal plates, 
counting from the median interradial line, is about 17 or 18 mm. 

Locality and Stratigrapliical Position. — This species appears to be confined to 
the Lower Chalk. Examples have been collected from Washington, Amberley, 
Southerham, and Glynde, in Sussex. Also from the Lower Chalk of Folkestone, 
and the Chalk Marl of Dover. 

History. — Two examples of this species were first figured by Forbes in Dixon's 
' Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex,' 
London, 1850, pi. xxiii, figs. 4 and 5. Both these specimens are now preserved 
in the British Museum. One example, which is from Amberley, is drawn on 
PI. Ill, fig. 1 a. The other, which is from Washington, is accurately represented 
by fig. 3 a of the same plate. 

Variations. — In addition to the difference noted above in the form of the 
stellate bases of the abactinal plates or paxillse, other minor differences may be 
observed. In some examples the breadth of the border formed by the marginal 
plates on the disk area is not relatively so great as in other examples, and the 
proportions of length to breadth, as well as the amount of tumidity of the 
component plates, are subject to variation. In some examples, again, the irregu- 
lai'ity in the granulation of the marginal plates, arising from the former presence 
of coarser granules interspersed amongst the average granulation, is more marked 
than in others. These differences will be more readily noticed by turning to the 
figures given on PI. II and PL III than by a lengthy verbal description. Some of 
tlie examples come from difi'erent beds and different localities — circvimstances 
which I consider to be sufficient to account for the variation. 



G^emis— NYMPHASTER, SJaden, 1885. 

Nympuaster, Sladen. In Narr. Chall. Exp., 1885, vol. i, p. 612 ; Zool. Chall. 

Exped., part li, Eeport on the Asteroidea, 1889, p. 294. 

Disk large and flat. Rays elongate, slender, tapering, and almost square in 
section. Marginal plates forming a broad border to the disk, and either united 



NYMPIIASTER COOMBII. 15 

along the median abactinal lino of the ray throughout, or separated only hy a single 
series of raedio-radial plates. The marginal plates of both series are granulated, 
and bear no spines (normally, but occasional incipient spinelets may be present). 
Abactinal area of the disk covered with large and regularly arranged plates, those 
in the radial areas well separated, usually hexagonal, more or less tabulate and 
paxilliform, and frequently bearing an excavate or entrenched pedicellaria. 
Actinal interradial areas large, confined to the disk. Actinal intermediate plates 
well defined, covered with uniform granules, and occasionally bearing pedicellariae. 
Armature of the adambulacral plates arranged in longitudinal series. Madre- 
poriform body exposed and situated within one third of the distance from the 
centre to the margin. Large entrenched pedicellarige are freqiiently present on 
the marginal plates in some species. 

This genus includes a number of recent species brought to light by the deep- 
sea explorations of late years. It has been found iu the Atlantic, the Pacific, and 
the Eastern Archipelago. The Atlantic species pass into the abyssal zone, but 
those inhabiting the Pacific and Eastern Archipelago do not, so far as at present 
known, extend beyond the continental zone, or in other words they live in depths 
of less than 500 fathoms. 

The structure and character of the Cretaceous species described in the 
following pages, so far as they can be made out from the fragmentary condition 
of the fossils, appear to me to warrant their inclusion iu the genus Nymphaster. 



1. Nymphaster Coombii, Forbes, sp. PI. VII, figs. 1 — 3 ; PL VIII, figs. 1 a, 1 h. 

GoNiASTEK (Asteogonium) Coombii, Forbes, 1848. Memoirs of the Geological 

Survey of Great Britaiu, vol. ii, 
p. 474. 

— — — — 1850. In Dixou's Geology and 

Fossils of the Tertiar}' and Cre- 
taceous Formations of Sussei, 
London, 4to., p. 334, pi. xiiii, 
fig.G. 

— — — Morris, 185L Catalogue of British Fos- 

sils, 2nd ed., p. 80. 
Asteogonium Combii, Dujardin and Hupe, 1862. Hist. Nat. 

Zooph. fichin. (Suites aBuffon), 

p. 399, 
GoMASTEE (Astboooniom) Coombii, Forbes, 1878. In Dixon's Geology of 

Sussex (new edition, Jones), 

p. 367, pi. x.\vi, fig. 6. 



16 FOSSIL ASTEROIDEA.. 

Body of medium size. Disk moderately large. Rays well produced, rather 
broad at the base aud tapering to the extremity. General form depressed and 
thin. Marginal contour stellato-pentagonal, the major radius measuring more 
than twice and a half the minor radius. Marginal plates broad, the supero- 
marginal series of the two sides of the ray meeting in the median radial line. 
Interbrachial arcs deeply indented and well rounded. Margin rather thin. 

The infero-marginal plates are more than fifteen in number, counting from the 
interradial line to the extremity. They form a broad conspicuous border to the 
actinal area, which is relatively broad in proportion to the size of the disk. The 
largest infero-marginal plates near the median interradial line measure about 
5'5 mm. in breadth, and about 2'5 to 2'75 mm. in length. The breadth decreases 
slightly from this point as the plates approach the base of the ray, and then 
much more rapidly, the plates on the outer part of the ray having the length 
considerably in excess of the breadth. The plates are tumid and roundly 
bevelled at the lateral edges, but are flatly rounded at the margin of the disk, and 
without tumidity there. The whole superficies of the plate is covered with large, 
rather deeply depressed, hexagonal punctations, closely placed, which give 
somewhat of a honeycomb appearance to the plate (see PL VIII, fig. 1 b). These 
are the marks left by the granules previously borne upon the plate. Upon a 
number of the plates in the example figured on PI. VIII, fig. 1 a, the granules are 
still preserved in situ. They are large and closely placed. The punctations, 
and consequently the granules, in this species are coarser than in any of the other 
Cretaceous forms known to me. I have not been able to assure myself of the 
presence in this example of any pedicellarise on the infero-marginal plates. 

The adambulacral plates are broader than long, except on the outer part of the 
ray, and their armature appears to have consisted of five or six regular series of 
spinelets. This is indicated by the presence upon the surface of the plate of that 
number of ridges, running parallel or subparallel to the ambulacral furrow, each 
having four or five articulatory elevations and intervening pits upon which 
spinelets had previously been borne. The spinelets were probably short, and 
similar to those described in GaUiderma Smithise and Galliderma mosaicum, but I 
have not found any preserved in specimens which I consider to be undoubted 
examples of Nymphaster Goombii. 

Dimensions. — In the type specimen, figured on PI. VIII, fig. 1 a, the major 
radius is more than 56 mm., and the minor radius 23 mm. The breadth of the ray 
between the fourth and fifth infero-marginal plates measures about 15 mm. 

Locality and Stratigrapkical Position. — The specimen figured is from the Lower 
Chalk of Balcombe Pit, Amberley. The species has also been obtained from the 



NYMPH ASTER COOMBII. 17 

Lower Chalk of Glytulc, Sussex ; as well as fi'om the Lower Chalk of Dover and 
the Isle of Wight. Other specimens of NyvipJiastfi; as to the reference of which 
to X. Coombii I am more or less doubtful, which show certain differences in 
structural details, are from the Grey Chalk of Folkestone and Dover, and from 
the Lower Chalk of Betchworth. Several examples in the Museum of Practical 
Geology, Jermyn Street, are labelled from the " Upper Chalk," but I am inclined 
to think that their reference to that horizon is more or less doubtful. 

History. — Tlie type of this species was found by Mr. G. Coorabe at Balcombe 
Pit, Amberley, and formed part of Mr. Dixon's collection. It is now preserved in 
the British Museum. It was first figured by Edward Forbes in Dixon's ' Geology 
and Fossils of the Tertiary and Cretaceous Formations of Sussex,' London, 1850, 
pi. xxiii, fig. 6. The same specimen is carefully represented on PI. VIII, figs. 1 a, 
1 6 of this memoir. 

Doubtful Examples of this Species. — Three specimens are figured on PI. VII, 
which I only place provisionally and with very great doubt under this species. I 
do not, therefore, at present propose to describe them in detail, or to definitely 
assign the characters they present as supplementary to those already given as 
belonging to Xi/mphasfer Coombii. 

1. Au example from the Lower Chalk of Betchworth, in which a portion of the 
actinal surface is preserved (PI. VII, figs. 1 a — 1 e). This specimen shows large 
infero- marginal plates somewhat longer in proportion to their breadth than in the 
type specimen, and their surface is covered with an extremely fine uniform puncta- 
tion. The latter character is altogether unlike that of examples which I consider 
to be true forms of Nijmphaster Coombii. But from this character alone, which 
recent forms show to be one subject to considerable variation, I shrink from 
taking any more definite step, at least until further material is available for study. 
This example has some of the adambulacral plates and actinal intermediate plates 
well preserved. The adambulacral plates (see PI. VII, fig. 1 c) conform to the 
description given above. The actinal intermediate plates are rhomboid in form, 
and their surface is covered with d(^ep, large, well-spaced pits, which indicate the 
former presence of a coarse uniform granulation. These plates are shown on 
PI. VII, fig. 1 e. The margin of this example is quite characteristic of Xym- 
phaster Coombii. The infero-marginal plates are seen to be low and more or less 
bevelled or sloping towards the margin ; whilst the supero-marginal plates are 
relatively rather higher and more abruptly bent at the junction of the actinal and 
lateral surfaces (see PI. VII, fig. 1 b). 

2. This is a badly preserved specimen from the Grey Chalk of Folkestone, in 
which nothing but the supero-marginal plates and the general outline are available 

3 



18 FOSSIL ASTEROIDEA. 

for determination (see PI. VII, figs. 2 a, 2 b). The marginal plates resemble in 
character those of the specimen just mentioned, and they are like them covered 
with a very fine punctation, unlike that of the typical Nijriiphaster Goombii. There 
are also fewer plates in that portion of the interbrachial arc which may be said to 
belong to the disk than in Nijmphaster Goombii, but as the example is smaller, this 
may probably be only a question of age ; or it may, like the punctation of this and 
the preceding example, be attributed to variation, which I am disposed to consider 
a not improbable reason for the differences, when regard is had to the horizon 
from which the fossils were obtained, and consequently the changed conditions of 
existence in which those Asterids probably lived. 

3. This specimen (figured on PI. VII, figs. 3 a, 3 b) is from the Lower Chalk 
of Glynde, Sussex, and I consider that its reference to Nymphaster Goombii is less 
doubtful than that of either of the two preceding examples. The fragment repre- 
sents a portion of the abactiual surface. The supero-marginal plates are large, 
and are covered with the characteristic coarse punctation of Ni/niphaster Goombii 
(see PI. VII, fig. 3 b). The supero-marginal plates of the two sides of a ray 
meet in the median radial line from the very base of the ray, distinctly charac- 
teristic of the genus Nymphaster. Comparing this example with the typical form 
of the species, there appear to be a much smaller number of supero-marginal 
plates in the interbrachial arc belonging to the true disk, and on these grounds I 
hesitate from accepting it positively as an undoubted example of this species until 
further material is forthcoming to throw light upon the amount of plasticity 
which may be accredited to this species. 



2. Nymphastee maeginatus, Sladen. PL VIII, figs. 4 a, 4 b. 

Body of medium size. General form depressed. Marginal contour stellato- 
pentagonal. Rays well produced, rather broad at the base, and tapering gradu- 
ally to a pointed extremity. Interbrachial arcs deep and rounded, the sweep of 
the curve from the tip of one ray to the tip of the neighbouring ray being of a 
paraboloid character. Margin rather thin. 

The supero-marginal plates form a broad and massive border to the abactinal 
area of the disk. There are six plates on each side of the disk counting from the 
base of one ray to the base of the neighbouring ray. All the succeeding plates 
along the ray meet the corresponding plate of the opposite side of the ray in the 
median radial line. The abactinal surface of the ray is thus occupied entirely by 
the supero-marginal plates throughout its length. 



NYMPIIASTER OLICJOPLAX. li> 

All tlie supero-marginal plates are of uniform height, excepting the normal 
diminution towards the extremity of the ray ; and all have the breadth greater 
than the length. The plates on each side of the median interradial line measure 
about 4 mm. in breadth and about 2 mm. in length ; and this length is maintained 
with very slight diminution until about midway between the base and the extre- 
mity of the ray, where the length is 1"75 mm., and the breadth is between 275 
and 3 mm. Sixteen supero-marginal plates are preserved in the longest ray of 
the specimen under description, counting from the median interradial line to the 
broken extremity. A few plates are apparently missing. Measured in the 
margin, the height of the plates is about 2-5 mm. 

All the supero-marginal plates are distinctly convex in the direction of their 
median line of breadth, ])y whicli each plate is very clearly marked out, and a 
highly ornate character is given to the species. The plates are also tumid and 
Avell rounded ou their marginal surface. The whole surface of the plates is 
covered with rather large, widely spaced punctations or pits, which have a pecu- 
liarly isolated appearance, unlike that of any other species (see PI. VIII, fig. 4 b). 
1 have not detected the presence of any pediccllariaB upon this example. 

The remains of a few isolated plates are preserved on the abactinal area of the 
fossil figured. They are all small and out of position, and are not available for 
description. 

Dimensions. — The specimen figured on PI. VIII, fig. 4 a, has a minor radius of 
about 12 mm. ; and the longest fragment of a ray preserved measures about 
35 mm. The extremity is wanting. The thickness of the margin is 4 5 mm. The 
breadth of the ray at the base between the third and fourth supero-marginal 
plates counting from the median interradial line is from 8 to 8"5 mm. 

Locality and Stratigraphical Position. — The example described is from the 
Upper Chalk near Bromley. It is preserved in the British Museum, and bears the 
registi'ation number 35,484. 



3. Nymphastkr oligoi'Lax, Sladen. PI. VIII, figs. Sa, :Vi. 

Body of medium size. General form depressed and thin. Marginal contour 
stellato-pentagonal. Rays narrow at the base and produced. Interbrachial arcs 
wide and rounded. Margin thin. 

The supero-marginal plates form a broad border to the abactinal area of the 



20 FOSSIL ASTEROIDEA. 

disk. There are only tliree (or possibly four) supero-marginal plates between the 
median interradial line and the base of the ray — that is to say, about six plates on 
each side of the disk. The fourth (or perhaps the fifth) plate counting from the 
median interradial line, and all the succeeding plates along the ray, appear 
normally to meet the corresponding plate of the opposite side of the ray in the 
median radial line. The abactinal surface of the ray is thus occupied entirely by 
the supero-marginal plates throughout its length. In one of the rays preserved 
there appear, however, to be traces of a few abactinal plates which interfere with 
the union of the supero-marginal plates in the median radial line near the base of 
the ray. As to how far this is normal I am unable to say. 

All the supero-marginal plates are comparatively low and flat. The plates on 
each side of the median interradial line are 3'5 mm. in breadth, and from 3 to 
3*5 mm. in length, and are thus practically square. Their abactinal surface is 
slightly convex; and their height as seen in the margin is less than the length, 
and the abactinal surface is gradually bevelled to the inferior margin which abuts 
upon the infero-marginal plates. The other plates which form the border of the 
disk-area are of the same size and character as those adjacent to the median inter- 
radial line. The supero-mai-ginal plates along the ray have the breadth greater 
than the length, the fifth plate counting from the median interradial line 
measuring about 3'75 mm. in breadth and 2'5 mm. in length. Their character is 
similar to that of the plates above described. The surface of the plates is covered 
with small well-spaced punctations, and there is a distinct smooth border on the 
inner and two lateral margins of each plate on which no punctations or pits are 
present. 

Large trench-like pedicellariee, which are nearly the length of the plate, are 
present in this species ; they occur more frequently on the infero-marginal plates 
than on those of the superior series ; in fact, only one or two are present on the 
latter series of plates in the example under description. 

No other portions of this fragment are available for description. 

Dimensions. — The fragment figured in PI. VIII, fig. 3 a, has a minor radius of 
about 15 mm. The longest portion of the major radius preserved is about 
33 mm., and the ray is broken off" abruptly. The thickness of the margin is 
between 4 and 5 mm. The breadth of the ray at the base is about 8 mm. 

Locality and Strati graphical Position. — The fragment described, which is, 
unfortunately, all that I have seen, is from the Upper Chalk of Bromley. It is 
preserved in the British Museum, and bears the registration number 40,178. 

Remarks. — The character of the marginal plates, as regards both their form 



PYCNASTER ANGUSTATUS. 21 

and their ornamentation, as well as the presence of the peculiar pedicellariae, 
and indeed tlie whole facies of this fossil, lend strong support to the presumption 
that this species may ultimately need to be placed in a distinct genus, but I do 
not feel warranted in taking that step on the basis of such scanty material. 



G«i«.s— PYCNASTER, Shulen. 

Disk relatively small and pentagonal. Abactinal surface more or less convex, 
and was probably somewhat inflated during life. Margin thick, and highest 
in the region of the disk. Rays elongate, narrow, and robust. IMarginal plates 
forming a broad border to the disk, and united along the median abactinal line of 
the ray throughout. The marginal plates are high and very robust, those of the 
superior series being prominently convex abactinally in the median line of breadth 
and height, which imparts a well-rounded character to the ray. The marginal 
plates of both series are finely granulated, and probably bore no spines. Actinal 
intermediate plates large, covered with uniform granules. Armature of the 
adambulacral plates arranged in longitudinal series. Foraminate pedicellariae 
with radiating channels may be present on the marginal plates. 

The fragmentary state of the fossils which I have referred to this type 
unfortunately does not permit of a complete diagnosis of the genus being drawn 
up. The characters above given appear, however, to me to be sufficient to 
warrant the recognition of the possessors of them as the representatives of a 
distinct genus. The small high disk, the massive convex marginal plates, 
and the large actinal intermediate plates, together with the form of the rays, 
produce a facies alone sufficient to stamp its individuality, irrespective of other 
details of structure. 



1. Pycnaster .\ngustatus, Forbes, sp. PL IX, figs. 1 a, 1 b. 

GoNiASTEK (Asthoqonium) ANGUSTATUS, Forbeg, 18-48. Memoirs of the Geolo- 
gical Survey of Great Britaiii, 
vol. ii, p. 47-i. 
— — — — 1850. In Di.xon'8 Qeolosty and 

Fossils of the Tertiarv and 
Cretaceous Formations of 
ISu88e.x, London, 4to., p. ;)3r», 
pi. xxiii, fig. 10. 



22 FOSSIL ASTEROIDEA. 

GoNiASTEH (Asteogonium) ANOusTATrs, Morris, 1854 Catalogue of British 

Fossils, 2nd ed., p. 80. 

AsTBOGONnrM akgustatum, Dujardin and Hupe, 1862. Hist. Nat. 

Zooph.Echin.(SuitesaBuftbn), 
p. 399. 

GrONiASTEE (AsTBOGONitFM) ANGTJSTATUs, Forbes, 1878. In Dixon's Geology of 

Sussex (uew edition, Jones), 
p. 368, pi. xxvi, fig. 10. 



Disk of medium size or relatively small and pentagonal. Rays elongate, 
narrow, robust, and, though tapering, nearly uniform in breadth throughout. 
Marginal contour stellate. Interbrachial arcs more or less flattened, which 
emphasises the pentagonal outline of the disk. Margin thick and robust, much 
highest in the region of the disk. Abactinal surface more or less convex, and was 
probably somewhat inflated during life. Actinal intermediate plates very large, 
covered with uniform granules. 

The supero-marginal plates are thick and massive, and they form a high and 
broad border to the disk. There are only three supero-marginal plates between 
the median interradial line and the base of the ray — that is to say, six plates on 
each side of the disk. The fourth plate counting from the median interradial 
line, and all the succeeding plates along the ray, meet the corresponding plate of 
the opposite side of the ray in the median radial line. The abactinal surface 
of the ray is thus occupied entirely by the supero-marginal plates throughout 
its length. 

The supero-marginal plates which form the border of the disk are much larger 
in the direction of height than any of the others. The plates on each side of the 
median interradial line are about 4'75 mm. in breadth as seen on the abactinal sur- 
face, and about the same measurement in length. They are convex abactinally, 
and well rounded at the junction of the abactinal and lateral surfaces. Measured 
in the margin their height is 8 mm., and theii' lateral surface (which forms the 
vertical wall of the margin) is distinctly convex or pulvinate, but to a less degree 
than their abactinal surface. 

The supero-marginal plates of the ray are not so high as those of the disk, 
although their height is greater than their length. The height of the sixth plate 
from the median interradial line is about 5 mm. Their abactinal and lateral sur- 
faces form together a true segment of a circle, and this imparts a well-rounded 
character to the ray. The plates are deeply bevelled at their junction with the 
adjacent plates, and consequently distinctly pulvinate in the median line of breadth 
and height. The surface of the plates is covered with minute punctations, but 



PYCNASTER ANGUSTATUS. 23 

these are so extremely faint that they are seen with difficulty. They are probably 
weather-worn in the example under notice. 

The infero-marginal plates, as seen in the direct lateral view of the margin, are 
much smaller in height than the supero-marginal series in the type specimen. 
The plates which form the margin of the disk are higher than long, the height 
being about 5 mm. and the length about 3"25 mm. in those adjacent to the 
median interradial line ; the succeeding plates on the margin of the disk are each 
less in height than the preceding plate, the third or fourth plate, counting from 
the median interradial line, having the height and length about equal. The infero- 
marginal plates along the ray have the length greater than the height. The 
surface of the infero-marginal plates resembles that of the superior series in the 
character of its punctation. 

Traces of small excavate pedicellarise are present on occasional plates, but 
these appear to have been very few in the example under description. 

On the abactinal surface of the disk a few isolated and displaced plates are 
present. Some of these seem rather thick and tuberculous in character, but the 
state of the preservation of this part of the fossil is unfortunately quite unfitted 
for description. 

There is a fine fragment of this species preserved in the Museum of Practical 
Geology, Jerrayu Street, from the Upper Chalk of Bromley, which shows part of 
the actinal surface. The infero-marginal plates in the disk are very high in this 
example, and five of them in an interbrachial arc bear a small foraminate pedi- 
cellaria. This is situated near the upper margin of the plate, about equidistant 
from that margin and the lateral margins of the plate, and consists of a small 
round foramen situated in the middle of a very shallow concavity, and with five 
or six faint channels radiating from the foramen to the margin of the concavity, 
gradually thinning and dying out there. The channels radiate like the spokes of 
a wheel, or a five-rayed star, and produce a facies unlike that of any other pedi- 
cellarian apparatus with which I am acquainted. The actinal intermediate plates 
are very large, and not more than three series are present. The plates of the 
series next to the adambulacral plates are much larger than the others, and are 
broader than long. The adambulacral plates are broader than long, and their 
surface is marked with throe or four ridges parallel to the furrow, upon which 
spinelets were previously borne. The furrow series consists of about five 
spinelets. A few of these spinelets are preserved, and they are rather short, 
cylindrical, and slightly tapering. The mouth-plates are very small and narrow. 

Dimensions. — The specimen figured on PI. IX, fig. 1 n, has a minor radius of 
about 23 mm. The longest portion of a major radius preserved is 53 mm. ; the 
ray is broken abruptly, and there is very slight diminution in the breadth at the 



24 FOSSIL ASTEROIDEA. 

broken extremity as compared with the breadth at the base ; there would appear to 
be every indication that only a small part of the ray is preserved. 

The thickness of the margin at the median interradial line is 13 mm., and 
at the base of the ray 8-5 mm. The breadth of the ray at the base is about 
12 mm. 

Locality and Stratigraphical Position. — The example above described, which has 
been drawn on PI. IX, fig. 1 a, was obtained from the Upper Chalk in Kent, but 
unfortunately the exact locality is unknown. It is preserved in the British 
Museum. A fine fragment preserved in the Museum of Practical Geology, 
Jermyn Street, was obtained from the Upper Chalk of Bromley. The species has 
also been found in the Upper Chalk of Sussex. 

Histor}/.--T\ie type of this species was first described by Forbes under the 
name of Goniaster {Astrogonium) angustatus, and was afterwards figured by him m 
Dixon's ' Geology and Fossils of the Tertiary and Cretaceous Formations of 
Sussex,' London, 1850, pi. xxiii, fig. 10. That illustration does not, however, 
give a good idea of the facies of the species. 



(?eft«s— PBNTAGONASTER, Lhick, 1733. 

Pentagonasteb, Linck. De Stellis marinis, 1733, p. 20. 

— Schulze. Betrachtuug der versteinerten Seesterne und ihrer 

Theile, Warschau u. Dresden, 1760, p. 50. 
GONIASTEE (pars), L. Agassiz. Prod. Mou. Eadiaires, Mem. Soc. Sci. Nat. 

Neuchatel, 1835, t. i, p. 191. 
AsTEOGONiUM (pars), Miiller and Troschel. System der Asteriden, 1842, p. 52. 
GoNiODiscus (pars), Miiller and Troschel. Ibid., 1842, p. 57. 
HosiA (pars), Gray. Ann. and Mag. Nat. Hist., 1840, vol. vi, p. 279. 

TosiA, Gray. Ibid., 1840, vol. vi, p. 281. 

Body depressed and pentagonal in contour, or with the rays slightly produced. 
Marginal plates smooth or granular, ordinarily few in number. Supero-marginal 
plates form a broad border to the disk, and, when the ray is produced, are sepa- 
rated throughout by abactinal plates. Abactinal area covered with rounded or 
polygonal plates, which may either be smooth or bear co-ordinated granules. 
Actinal intermediate plates and infero-marginal plates smooth or granulose, devoid 
of prominent spinelets. 

Much diversity of opinion has existed, unnecessarily it seems to me, as to the 



PENTAGONASTER LUNATUS. 25 

character and limits of this genus. Two species were originally referred to 
Pentagonaster by its founder. The type of one of these is now lost, and its identi- 
fication rests only on surmise. The second species, however, Pentagonaster semi- 
hcnafiis, is a well-known and widely distributed recent form, about which there is 
no doubt. I therefore consider that this form has evei'y claim to be regarded as 
the type of the genus. The existing species of Pentagonaster are found in the 
Atlantic, the Pacific, the Indian and the Southern Oceans, and in the Eastern 
Archipelago ; and the bathymetrical range of the genus extends from 20 to 1500 
fathoms or more. 



1. Pentagonaster lunatus, Woodioard, sp. PI. IV, figs. 1 a — 1 c. 

AsTERiAS LUNATUS, Woodward, 1833. An Outline of the Geology of Norfolk, 

p. 52, pi. V, fig. 1. 
TosiA tuNATA, Morris, 1843. Catalogue of British Fossils, p. GO. 

— — Bronn, 1848. Index Palaeontologicus, Nomenclator, p. 1274. 

Body of medium size. General form depressed. Abactinal and actinal areas 
flat. Marginal contour stellato-pentagonal, the major radius measuring nearly 
twice the minor radius. Rays short and moderately produced, rather narrow at 
the base and tapering to the extremity. Interbrachial arcs deeply indented and 
well rounded. 

The infero-marginal plates are twelve (or more) in number, counting from the 
median interradial lino to the extremity. They form a broad border to the actinal 
area of the disk, the breadth of which diminishes rather rapidly plate by plate as 
they recede from the median interradial line. The largest infero-marginal plates 
adjacent to the median interradial line measure about 5" 25 mm. in breadth and about 
3 mm. or a little more in length. The length and breadth decrease as each plate 
proceeds outward until about midway on the ray, where these dimensions are 
subequal. On the outer part of the ray the length is greater than the breadth. 
The infero-marginal plates are distinctly convex on their actinal surface in the 
direction of the median line of breadth, and are slightly tumid at the margin. 
Their surface is covered with small, uniform, closely placed, and deeply sunken 
moniliform punctations, upon which small granules were previously borne, probably 
uniform in size and closely placed (see PI. IV, fig. 1 c). I am not aware that 
traces of any pedicellarias have been detected on these plates. 

The adambulacral plates are small and oblong, and bear on their surface ridges 

4 



26 FOSSIL ASTEROIDEA. 

of alternating granuliform eminences and depressions, upon which the spinelets 
constituting the armature of the adambulacral plates were originally borne. 

The actinal interradial areas are small, and are covered with regular pentagonal 
or rhomboid intermediate plates, which are arranged in series parallel to the 
ambulacral furrow, and form a compact, mosaic-like pavement. The actinal inter- 
mediate plates are moderately large in relation to the size of the disk. The plates 
of the series adjacent to the adambulacral plates are sensibly larger than any of the 
others, and the plates of the next series are also larger than those which form the 
rest of the pavement. Near the infero-marginal plates the actinal intermediate 
plates become small and more or less irregular. The intermediate plates extend 
at the base of the ray to about the fifth infero-marginal plate, counting from the 
median interradial line. The surface of the plates is covered with rather large, 
widely spaced, and deeply sunken punctations, upon which granules were pre- 
viously borne, and these would appear to have been comparatively large in size and 
uniform (see PI. IV, fig. 1 b). 

From what is visible of the margin of this example it is seen that the supero- 
marginal series of plates are nearly of the same height as the infero-marginal 
series, and are similar in structure. 

Unfortunately no other portions of this fragment are available for description. 

Localitjj and Stratigraphical Position. — The specimen upon which this species 
was founded was collected by Mr. Samuel Woodward, from the Upper White 
Chalk, near Norwich. 

Dimensions. — In the type specimen (figured on PI. IV, fig. 1 a) the major 
radius is about 35 mm., and the minor radius about 18 mm. Breadth of the ray 
between the fifth and sixth infero-marginal plates about 10 mm. 

History. — The type specimen was figured by Woodward in his ' Outline of the 
Geology of Norfolk,' pi. v, fig. 1, and is now preserved in the collection of the 
Norfolk and Norwich Museum. It was kindly lent by the committee of that 
institution to Dr. Wright for the purpose of this monograph. It has been 
carefully drawn on PI. IV, figs. 1 a — 1 c. An admirably executed cast of this 
specimen is in the British Museum. I am not at present aware of the existence 
of any other examples of this rare form. 

Remarks. — The example referred by Forbes to this species, and figured by 
him in Dixon's ' Geology and Fossils of the Tertiary and Cretaceous Formations 
of Sussex,' London, 1850, pi. xxiii, fig. 9, belongs to a distinct species, which I 
have named Peidagonaster megaloplax. A number of other specimens in other 



PENTAGONASTER MEGALOPLAX. 27 

collections have, following Forbes, been erroneously referred to Pentagonaster 
lunatus, whicli are in reality examples of Pentagonaster megaloplax. This is 
unfortunate, for the latter form has thus become comparatively well known under 
the name of Pentagonaster lunatus, a name which they must now cease to bear, as 
the real Pentagonaster lunatus is quite a different form, and there is no doubt 
whatever either as to the type (which is preserved in Norwich) or the priority. 
The differences between the two species will be further noticed under the descrip- 
tion of Pentagonaster megaloplax. 



2. Pentagonastkr megaloplax, Sladen. PI. IV, figs. 2 — 4. 

GoNiASTEE (Asteoookium) LUNATUS, Forbes, 1850. In Dixon's Geology and 

Fossils of the Tertiary and Cre- 
taceous Formations of Sussex, 
London, 4to., p. 353, pi. xxiii, 
fig. 9 (non Asterias lunatus. 
Woodward, 1833). 

Body of medium size. General form depressed. Abactinal and actinal areas 
flat. Marginal contour stellato-pentagonal, the major radius measuring a little 
more than once and a half the minor radius. Rays short and not greatly pro- 
duced, tapering gradually to the extremity. Interbrachial arcs regularly rounded, 
curving gradually from the tip of one ray to that of the adjacent ray, which gives 
a distinctly lunate character to the disk. Margin of uniform thickness. 

The infero-marginal plates are only five or rarely six in number, counting from 
the median interradial line to the extremity. They form a very broad border to 
the actinal area of the disk in relation to its size, and the breadth is maintained 
until near the extremity. The largest infero-marginal plates adjacent to the median 
interradial line measure 7 mm. in breadth, and about G-5 mm. or nearly 7 mm. in 
length ; they are consequently almost square. The proportion of breadth dimin- 
ishes in the succeeding plates as they recede from the median interradial line. 
The infero-marginal plates have a more or less pulvinate appearance actinally, 
consequent on being rounded or bevelled at the edges ; and they are slightly 
tumid in the margin. Their whole actinal surface is covered with large, weli- 
spaced, deeply sunken pits, in the centre of which is a slight eminence — a struc- 
ture which has almost the character of a granule surrounded by a scrobicule (see 
PI. IV, fig. 2 h). On the surface which stands in the margin the punctations 
are fewer and more widely spaced on the upper half of the surface — that is to say, 



28 FOSSIL ASTEROIDEA. 

the half adjacent to the supero-marginal series (see PI. IV, fig. 4 c). I have not 
found any pedicellai'ise on these plates. 

The adambulacral plates are broader than long, except on the outer part of 
the ray, and bear on the surface four or five ridges with granuliform eminences, 
upon which the spinelets constituting the adambulacral armature were originally 
borne. In one well-preserved specimen these small articulatory tubercles are seen 
to have each a small microscopic central puncture (see PI. IV, fig. 3 c), but I am 
not certain whether this is always present. 

The actinal interradial areas are small, and are covered with a comparatively 
small number of large pentagonal or tetragonal intermediate plates, which are 
arranged in series parallel to the ambulacral furrow, and form a compact 
tessellated pavement. The actinal intermediate plates are larger in relation to the 
size of the disk than in the species above described. The plates of the series 
adjacent to the adambulacral plates, and a few of the plates of the succeeding 
series within the angle towards the mouth, are larger than the others. The 
intermediate plates do not extend beyond the second, or at most a short distance 
along the margin of the third infero-marginal plate, counting from the median 
interradial line. The surface of the intermediate plates, excepting a border 
round the margin of the plate, is covered with large punctations, which are nearly 
confluent, and in some cases almost give the appearance of a coarse reticulate 
superficial ornamentation ; the border round the margin of the plate above 
mentioned is marked with a concentric crenulation (see PI. IV, fig. 3 b). Within 
the pits are more or less definite elevations. In other examples the reticulate 
character is less marked, and the margin of the pit is then prominently lipped, 
and the marginal crenulation is not so strongly shown (see PI. IV, fig. 4 e). 

In the marginal view of the type specimen the supero-marginal plates are seen 
to be higher than the infero-marginal plates, and that their height is greater than 
their length, whereas in the infero-marginal series of plates the height is less than 
the length (see PI. IV, fig. 2 c). 

In other examples the mouth-plates are preserved. These are rather small, 
triangular, and covered with rather large, irregular, tuberculose eminences for 
the attachment of the mouth-plate armature. 

Variations. — Three examples of this species are figured on Plate IV. These 
present a number of minor differences, which will be readily noticed on referring 
to the figures. 

The example which is shown in fig. 3 a has the marginal border of the infero- 
marginal plates rather less bi'oad than in the type form, and it is especially 
remai'kable for the peculiar retiform and crenulated ornamentation of the actinal 
intermediate plates already noticed. The disposition of the armature of the 



THE 



PALiEONTOGRAPHlCAL SOCIETY. 



INSTITUTED MDCCCXLVil. 



VOLUME FOR 1893. 




LONDON: 

MDCCCXCIII 



A M (3 N O G R A P H 



ON THE 



BRITISH FOSSIL 



ECHINODERMATA 



FROM 



THE CRETACEOUS FORMATIONS. 

VOTAT.ME SECOND. 
THE ASTEROIDEA. 

BY 

W. PERCY SLADEN, F.L.S., F.G.S.. &c., 

SECRETAKT OF THE LIUNEAN SOCIETY. 



PART SECOND. 

Pages 29— (UJ ; Plates IX— XVI. 



LONDON: 

PRINTE]) FOR THE PA L^ONTOGR A PHIC AL SOCIETY. 

1803. 



PBLXTED BY ADLAED AXD SON, 
BAKIHOLOMEW CLOSE, EX., AND 20, HANOVEK SQUAEE, W. 



PENTAGONASTER MEGALOPLAX. 29 

adambulacral plates is also noteworthy. This seems to indicate the former 
presence of a distinct furrow series of spinelets or granules much smaller than 
usual, followed by granules or spinelets borne on the outer part of the plate, 
more irregulai'ly placed than in the other forms described, and articulated on 
punctured eminences. 

The example which is represented in fig. 4 a also has a narrower marginal 
border of infero-marginal plates than the type. The punctation of the infero- 
marginal plates is smaller than in the type, and does not present the striking 
scrobiculate character noticed in that example. The markings are rather to 
be described as lipped pits, and some granules are still in situ. The actinal 
intermediate plates do not have the retiform and crenulate ornamentation shown 
in the plates belonging to the specimen figured in 3 a, but the margins of the 
punctations are strongly lipped. The supero-marginal plates arc less regular 
and much less high than in the type specimen, but they are not perfectly 
preserved. 

Dimensions. — In the type specimen (figured on PI. IV, fig. 2 a) the major 
radius is about 41 mm., and the minor radius 26 mm. Breadth of a ray between 
the third and fourth infero-marginal plates, counting from the median interradial 
line, about 12 mm, or rather more. Thickness of the margin about 85 mm. 

The specimen given in fig. 3 a has a major radius of about 39 mm. and a 
minor radius of 24 mm. 

The specimen given in fig. 4 a has a major radius of about 41 mm. and a 
minor radius of 25"5 mm. Breadth of the ray between the third and fourth 
infero-marginal plates about ] 1 to 12 mm., or rather more. 

Locality and Stratigraphical Position. — The type specimen, which is now pre- 
served in the British Museum, is labelled from the " Lower Chalk " of " Sussex," 
but is stated by Forbes to have been obtained from the Upper Chalk. Other 
examples of the species have been collected from the Upper Chalk of Bromley, 
Sittingbourne, Purflect, G-ravesend, Sussex, and Wiltshire. Fine series are pre- 
served in the British Museum and in the Museum of Practical Geology, Jermyn 
Street, 

History. — The specimen which I have taken as the type of this species was 
originally referred by Forbes to the Asterias lunatus of Woodward, and was 
figured by him as that species in Dixon's ' Geology and Fossils of the Tertiary 
and Cretaceous Formations of Sussex ' (pi. xxiii, fig. 9), The same example is 
carefully represented on PI, IV, fig. 2 a, of this memoir. 

5 



30 FOSSIL ASTEROIDEA. 

Remarks. — It will be at once seen on referring to the figures that Woodward's 
Pentagunaster lunatns, which is drawn on PI. IV, fig. 1 a, of this Monograph, is a 
distinct species. The rays are more jDroduced, and are narrower at the base. The 
infero-marginal plates are twice as numerous, the marginal border is less broad, 
and the plates are much shorter in proportion to their breadth. Their punctation 
is also different. The actinal intermediate plates are smaller in relation to the size 
of the actinal interradial areas, and their punctation is different from that which 
characterises Pentagonaster megalojdax. The armature of the adambulacral plates 
also appears to be more regular in its arrangement. 

Under these circumstances I have no hesitation in considering the form under 
description a distinct species. 1 much regret having to impose a new name, as 
this form has for a long time been known under the specific name of lunatus ; 
the course, however, seems unavoidable, as the actual type of the real Pentago- 
naster lunatus described by "Woodward is in existence, and there can, in my 
opinion, be no question as to its being a diff"erent species. 

Since the preceding sheet was printed off I have found several specimens in 
the British Museum which show the abactinal aspect of the disk. I have little 
hesitation in referring these examples to Pentagonaster megaloplax, and a drawing 
of one of them is given on PL XIII, fig. 1 a. The infero-marginal plates all show 
more or less distinctly the characteristic " scrobiculate " or areolated pits already 
described. A similar ornamentation also extends upon the supero-marginal 
plates, but is confined to the lateral wall which falls in the margin of the disk. 
The curvature which unites the abactinal and lateral areas of the plate is more or 
less abrupt, and the lateral wall of the disk is consequently vertical and not 
rounded, as a rule. The abactinal area of the supero-marginal plates is covered 
with small, uniform, granular eminences (see PL XIII, fig. 1 h). Two or three 
supero-marginal plates at the extremity of the ray meet the corresponding plates 
of the opposite side of the ray in the median radial line, and a rapid diminution 
in breadth occurs as they approach the extremity. 



Ge?i«s— METOPASTBR, Sladen. 

[MiTwirof = a cheek-piece.] 

Body depressed and pentagonal or stellato-pentagonal in contour, the rays 
being produced to a very slight degi'ee. Marginal plates covered with well- 
spaced uniform punctations, upon which granules were originally borne, and 
surrounded by a narrow depressed border with very minute and crowded puncta- 



.METOPASTER PARKINSONI. 61 

tions for the articulation of setae. Supero-marginal plates ordinarily few in 
number, and form a broad border to the disk. Ultimate paired supero-marginal 
plates the largest of the series. Abactinal area covered with polygonal, and 
usually hexagonal, plates (some of which may have stellate bases), and upon the 
tabulae are borne small, more or less co-ordinated granules. Infero-marginal 
plates more numerous than the supero-marginal series, and decreasing in size as 
they approach the extremity of the ray. Their ornamentation similar to that of 
the superior series. Actinal intermediate plates small, polygonal, covered with 
uniform granules. Armature of the adambulacral plates arranged in lonoritudinal 
lines. Small entrenched pedicellarias may be present occasionally on the plates. 

Metopaster differs from Pentagonaster by the large ultimate paired supero- 
marginal plates, by the comparatively small number of the supero-marginal plates, 
which are also fewer in number than the infero-marginal series, and by the 
character of the ornamentation of the marginal plates of both series. 

The forms ranked under this genus were all classed by the late Professor 
Edward Forbes under Goniodiscus, which he considered to be a sub-o-enus of 
Goniaster. There is, however, no justification whatever in my opinion for regard- 
ing any of the Cretaceous starfishes hitherto described as belonging to either the 
genus Goniaster or Goniodiscus. The species which may be considered as the types 
of each of these genera are existing forms, and no Cretaceous forms agreeing in 
structural detail have, so far as I am aware, been discovered. It is also erroneous 
to rank Goniodiscus as a sub-genus of Goniaster. The two genera belong to 
different families ; and I am in perfect accord with Professor Edmond Perrier as 
to the limitation of the two genera. His view appears to me to be perfectly 
logical, and to be the result of careful and impartial judgment. I also consider 
that the fossil forms under consideration are quite distinct from the recent genus 
Astrogonixim, as limited by me elsewhere.^ 



1. Metopastee Paekinsoni, Forbes, sp. PI. IX, figs. 2 a— 2 c ; PI. X, figs. 1 a— 

5 c ; PI. XI, figs. 1 a— 2 c ; PI. XII, 
figs. 1 a— I d ; PI. XVI, figs. 2 a, 2 b. 

Pentagonastee EEGULAEI8, Parkinson, 1811. Organic Reniaius, vol. iii, p. 3, pi. i, 

fig. 3 (non Linck). 
TOBIA EEQULAEis, Morris, 1843. Catalogue of British Fossils, p. 60. 



1 < 



Zool. Chall. Exped.,' part li, "Eeport ou the Asteroidea," 1889, p. 285. 



32 FOSSIL ASTEROIDEA. 

GoxiASTEB (GoNioDisctis) PAHKiNSoia, Forhes, 1848. Memoirs of the Greological 

Survey of Great Britain, vol. ii, 
p. 472. 

— — EECTiLiNEns, McCoy, 1848. Ann. and Mag. Nat. 

Hist., ser. 2, vol. ii, p. 408. 

— — Paekinsoni, Forbes, 1850. In Dixon's Geology and 

Fossils of the Tertiary and Cre- 
taceous Formations of Sussex, 
London, 4to, p. 332, pi. xxi, 
figs. 10, 11 ; pi. xxii, figs. 5 — 7. 

— — — Morris, 1854. Catalogue of British 

Fossils, 2nd ed., p. 81. 

— — EECTiLiNETJS, McGoy, 1854. Contrib. Brit. Pal., p. 55. 

— — — Morris, 1854. Catalogue of British 

Fossils, 2nd ed., p. 81. 
AsTEOGONirAi Paekiusoni, Dujardin and Rupe, 1862. Hist. Nat. 

Zooph. fichin. (Suites a Buffou), 

p. 399. 
— fiECTiLiNEUM, Dujardin and Rupe, 1862. Ibid., p. 400. 

Goniastee (Goniodiscus) Paekinsoni, Forbes, 1878. In Dixon's Geology of 

Sussex (new edition, Jones), 

p. 365, pi. xxiv, figs. 10, 11; 

pi. XXV, figs. 5 — 7. 
Pentagonastee EECTILINETJS, Woods, 1891. Catalogue of the Type 

Fossils in the Woodwardian 

Museum, Cambridge, p. 36. 

Body of medium size. General form depressed. Abactinal surface flat, with 
a tendency, however, for the extremity of the rays to be slightly upturned ; as 
found in the fossil state the area occupied by the abactinal plates is usually at a 
lower level than the marginal plates, which leads to the assumption that the 
abactinal floor had collapsed or fallen to a certain extent on the death of the 
animal. Actinal surface slightly convex. Marginal contour pentagonal, with 
slightly lunate sides, the curvature being often flattened at right angles to the 
median interradial line. The major radius measures about one-third more than 
the minor radius, and frequently less than one-third ; the rays are consequently 
very feebly produced. Margin thick and well rounded. 

The supero-marginal plates are four in number, counting from the median 
interradial line to the extremity, or eight from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. 
They form a broad border to the abactinal area of the disk of uniform breadth 
throughout, which measures about 9 mm. at the median interradial line in an 
example whose minor radius measures 30 mm. Excepting the ultimate paired 
plates all the supero-marginal plates are of equal size, the breadth being about 



METOPASTER PARKINSONI. 83 

twice the length, the actual measurements in the specimen under notice being, 
length 475 mm, and breadth 9*5 mm. respectively, ?. e. as 1 : 2. The abactinal 
surface of these plates is distinctly convex, with a slight depression along their 
margins of juncture, formed by a well-defined bevel along the sides and adcentral 
end. The general surface of the whole series is well rounded, the curvature 
being regular and uninterrupted between the adcentral margin of the plate and 
the margin in the lateral wall adjacent to the infero-marginal plates. The height 
of the plates as seen in the margin is a little greater than their lengtli, and there 
is no diminution in height as the plates approach the extremity of the ray — in fact, 
the ultimate paired plate is not unfrequently higher than the other plates in 
consequence of a tendency to become gibbous on its abactinal surface. The 
whole superficies of the plates is covered with small, widely spaced, equidistant, 
uniform punctations, and there is a depressed border along the margin of the 
plate, varying slightly in breadth in difierent examples, covered with much 
smaller and closely crowded punctations, upou which much smaller granules than 
those upon the median area of the plate were originally borne. Traces of these 
granules may occasionally be found iii situ. 

The ultimate paired plate is larger than any of the other sujsero-marginal 
plates, and is of a different shape. It is subtriangular in form as seen from 
above, and one margin touches the corresponding plate of the adjacent side of the 
disk throughout, the junction coinciding with the median radial line of the disk. 
The length of this margin of the plate is subequal to or only slightly greater than 
the breadth of the preceding marginal plates. In small specimens the subequal 
measures are the rule, whilst in larger examples the plate becomes more elongate 
and produced in the direction of the prolongation of the ray. When viewed in 
the margin of the test the form of the ultimate plate strikingly resembles that of 
the carapace of some Coleoptera. The length of the plate in this aspect, measured 
from its outer extremity to the margin adjacent to the penultimate plate, is in 
small and medium sized specimens about once and a half the length of the other 
marginal plates, but in large examples it may be as much as, or even exceed, 
twice their length. The surface of the ultimate plate bears a similar ornamenta- 
tion to that on the other supero-marginal plates. 

The odd terminal plate is very small, appearing externally when denuded of 
granides like a truncate cylinder, having a fanciful resemblance to a cannon 
projecting from a porthole. This plate seems to be very rarely preserved in situ 
in the fossil state. In a remarkably good specimen belonging to the British 
Museum Collection (marked " E 2034") (see PI. XVI, figs. 2 a, 2 b) each of the 
terminal plates preserved bears at its outer truncate extremity a single horizon- 
tally placed entrenched pedicellaria. Whether this regularly placed pedicellaria is 
always present on the odd terminal plate in this species I am unable to say. 



34 FOSSIL ASTEROIDEA. 

The abactinal area of the disk within the boundary of the marginal plates is 
covered with small sub-regular plates or paxillar tabula, an hexagonal form pre- 
dominating especially in the radial regions ; and a small but distinct diminution in 
size takes place as the plates approach the margin of the disk. All the plates 
have their surface marked with minute, shallow, and closely placed punctations — 
the impressions of the attachment of the granules previously present. The 
primary basal plates are larger than any of the other abactinal plates, and they 
are well shown in sevei^al of the drawings illustrative of this species (see PL X, 
figs. 1, 2 a). Occasional plates bear small entrenched pedicellarise, the normal 
form consisting of a small, central, lipped foramen with a lateral trench on each 
side. It frequently happens, however, that the organ exhibits a more complex 
development, and assumes a stellate form in consequence of the presence of addi- 
tional trenches — five or six being not an unusual number — which radiate from the 
central foramen ; the whole being placed on a small hemispherical elevation, and 
producing an appearance shown on PI. X, fig. 2 d. 

The madreporiform body is large and subtriangular in outline ; and its surface 
is sculptured by very fine striations which radiate from the centre to the margin, 
with more or less wavy lines here and there (see PI. X, fig. 2 c). The margin 
of the plate is surrounded by three large plates, one on the adcentral side of 
the madreporite towards which it presents a straight suture; the other two 
plates are on the remaining sides of the triangular body, and they have a 
concave curve directed towards the madreporite to correspond with the 
convexity of its sides. The position of the madreporite is nearer the centre of 
the disk than the margin. 

The infero-marginal plates are seven in number, counting from the median 
interradial line to the extremity — that is to say, there are fourteen for the whole 
side of the disk, as against eight in the supero-marginal series. The length of 
the three innermost plates on each side of the median interradial line is equal to 
that of the superior series, but there are four infero-marginal plates corresponding 
to the large ultimate supero-marginal. As seen in the lateral wall of the disk the 
height of the infero-marginal plates is less than that of the supero-marginal series. 
The breadth of these plates adjacent to the median interradial line on the actinal 
surface is 7*5 mm. in an example whose major I'adius measures 36'5 mm. and the 
minor radius 27"5 mm. The breadth of the marginal border rapidly diminishes 
towards the extremity of the ray. The surface of the plates is ornamented in a 
precisely similar manner to that of the supero-marginal plates. A narrow border 
of smaller granulation is also present round the whole margin of the plate, 
similar in all respects to that already described in the case of the superior 
series of plates. 

The adambulacral plates are small, about or nearly twice as broad as long, and 



METOPASTER PARKlNSOiNI. 35 

their surface is traversed by four or five ridges running parallel to the auibulacral 
furrow, with punctures upon which the spinelets composing the armature were 
articulated. There were four or five spinelets in each lineal series. The spinelets 
are short, their length being about equal to the length of the plate, stumpy, com- 
pressed, slightly tapering and rounded at the extremity ; and all appear to have 
been uniform. 

The actiiial intermediate plates are rather large for the genus ; those adjacent to 
the adambulacral plates are pentagonal in form, but elsewhere they are subhexagonal, 
or perhaps more correctly polygonal. The plates are very large on the inner 
portion of the area, but diminish greatly in size at the outer margin of the disk 
adjacent to the marginal plates. The surface of the intermediate plates is entirely 
covered with small, equidistant punctations, upon which a uniform close granulation 
was previously attached. Remains of this granulation are still occasionally to be 
seen in situ on plates here and there in the example under notice. Entrenched 
pedicellaritB similar to those above described on tlie plates of the abactinal surface 
occur on a number of the plates in the series adjacent to the adambulacral plates, 
but the organ does not appear to diverge, or only very rarely, from the normal 
form of a central foramen and two lateral trenches. 

Dimensions. — In the specimen figured on PI, X, fig. 2 a, the major radius is 
38 mm., and the minor radius 30 mm. Other examples have the following 
approximate measurements : R = 85 mm., r = 27 mm. ; E, = 43 mm., r = 34 mm. 
The diameter of the disk (R -|- r) in well-grown tests ranges, therefore, from 
60 mm. to 80 mm. The thickness of the margin is about 11"75 mm. 

Localitif and Stratigrapldcal Position. — All the examples figured in this 
Monograph were obtained from the Upper Chalk, near Bromley. The species is 
a characteristic Upper Chalk fossil in the south of England, and has been found 
in beds of that age at Brighton, Charlton, Gravesend, Kent, and other localities. 
It is stated by Forbes to occur in the Lower Chalk of Sussex, but I have not seen 
any examples from that horizon. 

Historij. — A fossil starfish which has been generally considered to bo this 
species was figured by Parkinson in his * Organic Remains of a Former World,' 
vol. iii, pi. i, fig. 3, but it was referred by that author to the Pentagonaster 
regularis of Linck. The last named has, however, been supposed to be a recent 
species, but the type has unfortunately been lost, and the form has not subse- 
quently been recognised definitely. Apart from this the fossil starfishes now 
under notice are certainly distinct from the form indicated by Linck's figure, and 
this view was taken by Forbes, who named the species after Parkinson in his 
memoir ' On the Asteriada; found fossil in British Strata,' and figures of the 



36 FOSSIL ASTEROIDEA. 

fossils so named by him were given in Dixon's ' Geology and Fossils of the 

Tertiary and Cretaceous Formations of Sussex,' London, 1850. One, if not 

more, of the specimens delineated in that work is now preserved in the British 
Museum. 

Variations. — In some examples the breadth of the border formed by the 
supero-marginal plates on the abactinal surface is greater in relation to the disk- 
area than in others, and this variety was noted by Forbes (' Mem. Geol. Surv.,' 
vol. ii, p. 472). I have not been able to establish the relation of this modification 
with any other permanent morphological character, nor to associate it with any 
special locality or stratum, and I am therefore led to consider, for the present at 
least, that the variation in question is one affecting individual examples of the 
species independently of other structural modifications which would warrant 
recognition by name. 

Two other variations are to be noted in this species which are superficially 
much more striking, and either of them would, if only isolated examples were 
known, lend a strong temptation to the separation of their possessor from the 
normal form of the species. One of the variations in question affects the large 
ultimate paired supero-marginal plates. On comparing the examples drawn on 
PI. X, fig. 1 and fig. 2 a, with fig. 1 a, PI. XII, and fig. 1 a, PI. XI, it will be seen 
that the ultimate plates are relatively much larger than the adjacent supero- 
marginal plates and are more produced at the extremity ; whilst in the specimen 
delineated in fig. 2 a, PI. XI, this modification is carried to such an extent that 
at first sight it would appear scarcely possible to believe that this fossil belongs 
to the same species as, for example, fig. 2 a, PI. X. I have, however, been unable 
to find any other constant variation from what has been considered the typical 
form of Metopaster Parkinsoni associated with this modification in the size and 
shape of the ultimate plates ; and as the most complete gradation between the two 
extremes may be traced in the splendid series of specimens now preserved in the 
British Museum, all obtained from the same locality and the same horizon, no 
reasonable doubt can be entertained that the variation in question is of a 
comparatively trivial character, affecting the individual independently, and that it 
is not stamped by correlation with other structural modification with sufficient 
importance to justify the forms being separated from the species, or even a name 
being given to the variety. All the examples referred to in the foregoing remarks 
and figured in the plates accompanying this Memoir are from the Upper Chalk, 
and were obtained from the same locality near Bromley. 

The fine specimen with large and greatly produced ultimate plates drawn on 
PI. XI, fig. 2 a, is also an example of the second variation in the structure of this 
species, to which I have alluded. This manifests itself in the presence of an 



METOPASTER PARKINSONI. 87 

additioual supero-marginal plate. It will be seen that there are nine supero-marginal 
plates, exclusive of the terminals (or so-called oculars) on each side of the penta- 
gonal disk. At first sight the presence of this odd intermediate marginal plate in 
association with the strikingly modified ultimate plates found in this example 
would appear sufficient to indicate a well-marked variety, if not actually a distinct 
species. A careful examination of the collection in the British Museum shows, 
however, that this assumption is untenable, for in another example (which bears 
the Museum number " 46,765 "), which also possesses an odd intermediate marginal 
plate on two of its sides, the ultimate plates are in no way specially abnormal in 
their form or size. The presence of the additional supero-marginal plate would 
in this case, therefore, appear to be only an occasional variation, and, so far as I 
am able to detect, occurring independently of other structural modifications. I 
have observed no differences either in the proportions or the ornamentation of the 
intermediate marginal plates worthy of remark. This view is strengthened, if not 
absolutely confirmed, by the presence in another specimen (British Museum number 
" 46,796 "), drawn on PI. XII, fig. 1 a, of nine supero-marginal plates on two sides 
only of the disk, the remaining three sides having the normal number of eight 
marginal plates. In this example the ultimate plates are distinctly larger and more 
produced than in the truly normal forms of the species, but it will be noticed that 
their development is unequal, as is also the case in No. " 46,765 ; " in other words, 
in three of the rays one of the ultimate plates is smaller than the corresponding 
ultimate plate to which it is adjacent. The two sides which have an additional 
marginal plate are also the sides which have one of the smaller ultimate plates, 
and the inference naturally follows that the additional plate is to balance or com- 
pensate for the smaller size of the ultimate plate ; and I am inclined to think that 
the additional plate is not in this case a true odd interrndial marginal plate at all, 
such as occurs in Gnathaster, Sladeu, but that it is only a supplementary plate 
formed because its primitive or embryonic rudiment has not been included in the 
series merged together during development to form the structurally compound 
ultimate plate. That these ultimate plates are compound, or formed by the union 
of several embryonic plates, there is in my opinion little doubt when regard is had 
to the embryonic history of the ultimate plate and the associated infero-marginal 
plates. 



38 FOSSIL ASTEROIDEA. 



2. Metopasteb Mantelli, Forbes, sp. PI. XIII, figs. 2a — 4b. 

Pentagonastee SEMILT7NATUS, Parkinson, 1811. Organic Eemaius of a 

Former World, vol. iii, p. 3, 
pi. i, tig. 1 (non Linek). 
? G-ONIASTEE SEMILTJNATA, , Mantell, 184J. The Medals of Creation, 

London, vol. i, p. 338, Hgn. 75 
{lion Liuck, ? nee Parkinson). 

GoiTiASTEE (GONIODISCTJS) Mantelli, Forles, 1848. Memoirs of the Geological 

Survey of Great Britain, 
vol. ii, p. 472. 

— — — Forbes, 1850. In Dixon's Geology and 

Fossils of the Tertiary and 
Cretaceous Formations of 
Sussex, London, 4to, p. 332, 
pi. xxiii, figs. 11, 12. 

— — — Morris, 1854. Catalogue of British Fos- 

sils, 2nd ed., p. 81. 
? — Mantelli, Mantell, 1854. The Medals of Creation, 

London, 2nd ed., vol. i, p. 307, 
lign. 98. 

AsTKOOONiTJM MaNTELli, Dujardin and Hupe, 1862. Hist. Nat. 

Zooph. Echin. (Suites a 
Buffon), p. 399. 

GoNiASTEE (GoNiODiscus) Mantelli, Forbes, 1878. In Dixon's Geology of Sussex 

(new edition, Jones), p. 366, 
pi. xxvi, figs. 11, 12. 

Body of medium or rather small size. General form depressed. Abactinal 
surface flat, with the area circumscribed by the supero-marginal plates plain and 
rather sunken below the level of the median convexity of the border formed by 
these plates. Actinal surface plain, or may be a little convex in consequence of a 
tendency to a slight upturning of the rays in some examples. Marginal contour 
pentagonal, with sides faintly lunate, or in small examples they may be almost 
straight. The major radius measures scarcely one-third more than the minor 
radius. Margin rather thin, but well rounded. 

The supero-marginal plates are four in number, counting from the median 
interradial line to the extremity, or eight from the tip of one ray to the tip of 
the adjacent ray, exclusive of the odd terminal or "ocular" plate in each case. 
In one example, which is figured by Forbes in Dixon's ' Geology of Sussex,' 



METO PASTE 11 MANTELLI. 3» 

there would appear to be only seven plates on the entire side, but only one 
radial angle is preserved intact, and much displacement of plates has occurred. 
The circumstance is in any case of comparatively trifling importance. The 
supero-marginal plates form a conspicuous and moderately broad border to the 
abactinal area of the disk, of uniform breadth throughout, and measuring about 
6 mm. at the median interradial line in an example whose minor radius measures 
about 25 mm. 

Excepting the ultimate paired plate all the supero-marginal plates are nearly 
subequal in size ; the plates, however, adjacent to the median interradial line are 
slightly longer in relation to their breadth than those adjacent to the ultimate 
paired plate. The plates adjacent to the median interradial line have the appear- 
ance of being nearly square in outline as seen from above, the actual dimensions 
in the specimen under notice, whose side measures 38 mm., being length 5 mm., 
and breadth (> mm. In a smaller example, with a side measurement of 29'5 mm., 
the corresponding plate is 3"5 mm. long and 45 mm. broad. In Forbes's type 
the measurements are, length 3-75 mm., and breadth 5 mm. 

The abactinal surface of the supero-marginal plates is slightly tumid, and the 
general surface of the whole series forms a well-rounded regular curve from the 
adcentral margin to the margin in the lateral wall adjacent to the infero-marginal 
plates. The height of the plates as seen in the margin is less than their length, 
the actual measurement being about 3 mm. Their abactinal contour is distinctly 
convex, but not gibbous. The whole superficies of the plates is covered with 
small, widely spaced, equidistant, uniform punctations. In some examples which 
have been subjected to much weathering the punctations are almost obliterated, 
as in the case of the fine specimen shown on PI. XIII, fig. 2 a. A narrow 
depressed border surrounds the margin of the plate, bearing very small, closely 
crowded punctations, those adjacent to the main or median area being in serial 
arrangement. Occasionally a small entrenched pedicellaria may be detected on 
the median area of the plate (see PI. XIII, fig. 2 b). 

The ultimate paired plate is small and triangular in outline as seen from above, 
and one margin touches the corresponding plate of the adjacent side of the disk 
throughout, the junction coinciding with the median radial line of the disk. The 
length of the plate — that is to say, of the side of the plate which falls in the margin 
of the disk — is a trifle greater than the length of the largest supero-marginal 
plate, measuring in the example under notice nearly 5*5 mm., whereas the 
breadth of the plate, or measurement of the side adjacent to the penultimate 
supero-marginal plate, is not more than 5 mm. Near the outer or apical extremity 
of this plate when seen from above there is frequently a more or less strongly 
developed tendency to gibbo.sity present. 

The abactinal area of the disk within the boundary of the marginal plates is 



40 FOSSIL ASTEROIDEA. 

■covered with small subregular hexagonal plates or paxillar tabulae, which are, 
however, comparatively large for the size of the species. The primary apical 
plates are large and conspicuous, and all the plates in the central area of the disk 
and in the interradial areas are considerably larger than elsewhere ; all diminish 
in size as they approach the margin of the disk. All the plates have their surface 
covered with a small, uniform, closely placed granulation, in which an indefinite 
subcircular arrangement in relation to the centre of the plate is discernible (see 
PI. XIII, fig. 2 d). 

The madreporiform body is small and subtriangular in outline ; its surface is 
sculptured by fine striations which radiate from the centre to the margin. The 
madreporite is usually enclosed by three plates, but four may be present in conse- 
quence of the division or retarded development of one of them, as is the case in 
the example figured on PI. XIII, fig. 2 c. The position of the madreporite is 
rather nearer the centre of the disk than the margin. 

The infero-marginal plates are at least six in number, counting from the 
median interradial line to the extremity, — that is to say, there are twelve (or 
perhaps more) for the whole side of the disk, as against eight in the supero- 
marginal series. The length of the three innermost plates on each side of the 
median interradial line is equal to that of the superior series, but there are three 
infero-marginal plates corresponding to the ultimate paired supero-marginal. As 
seen in the lateral wall of the disk, the height of the infero-marginal plates is greater 
than that of the supero-marginal series. The breadth of these plates, adjacent to 
the median interradial line on the actinal surface, is 5 mm. in an example whose 
minor radius measures about 15 mm. The breadth of the marginal border appears 
to be well maintained till near the extremity. The surface of the plates is 
ornamented in a similar manner to that of the supero-marginal plates, excepting 
that the punctations on the main area are rather more numerous, and that the 
finely punctate depressed border round the margin of the plate is much broader 
than in the plates of the superior series ; the border is broader on the adcentral 
margin of the plate than elsewhere. (Compare figs. 3 b and 4 h on PI. XIII.) 

The adambulacral plates appear to be comparatively small, but their preserva- 
tion in the examples examined is not sufficiently good to permit of description. 

The actinal intermediate plates, which are small and hexagonal, are covered 
with small, closely crowded, uniform granules. All are much displaced in the 
specimens under notice. 

Dimensions. — In the example figured on PI. XIII, fig. 2 a, the major radius is 
about 32 mm., and the minor radius about 25 mm. The length of the side is 38 
mm. The thickness of the margin is about 8 mm. In Forbes's type (PI. XIII, 
fig. 3 a) the major radius is about 20 mm., and the minor radius about 15'5 mm. ; 



METOPASTER MANTELLI. 41 

the length of the side about 25*5 mm. In a very finely preserved cast from the 
Upper Cretaceous beds of Haldon the length of the side is 29'5 mm. 

Locality and Stratigraphical Position. — All the examples of this form with 
which I am acquainted are from the Upper Chalk. One of Forbes's type is from 
Gravesend, but the locality of the other is not recorded. The large example 
figured on PI. XIII, fig. 2 a, is from the Upper Chalk near Bromley. 

An extremely well-preserved cast in flint from the Upper Cretaceous beds 
of Haldon (Devonshire) is in the collection of the Albert Museum, Exeter ; and a 
cast of this example may be seen in the Museum of the Geological Survey, Jermyn 
Street. 

History. — This form appears to have been first recognised by Parkinson, who 
erroneously referred it to the Pcntagonaster semilunatus of Linck. The latter is a 
well-known recent species, and quite distinct from the fossil under consideration. 
Mantell, following Parkinson's determination, referred to the form under the 
name of Goniaster semilunata. Forbes was the first to indicate that these views 
of his predecessors were incorrect, and diagnosed the species in his memoir ' On 
the Asteriadae found fossil in British Strata ' under the name of Goniaster {Gonio- 
discus) Mantelli ; and figures of two examples were subsequently given in Dixon's 
' Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex,' 
London, 1850. Both these specimens are now preserved in the British Museum. 
Careful drawings of each fossil are given on PL XIII, figs. 3 a and 4 a. 

Hemarks. — It is not without hesitation that I maintain this species of Forbes's 
as independent from Metopaster Parkinsoni. For the present, however, I 
consider it to be distinguished by the smaller size, the comparative sijuareness 
of the supero-margiual plates, the small size of the ultimate paired plates, as 
well as by the character of the ornamentation of the supero-marginal plates and 
of the abactinal plates. Whether a more extensive series of specimens will break 
down or uphold these distinctions I do not feel prepared to say. It is undoubted 
that the two forms are very nearly allied. 

I feel considerable doubt as to whether one of Forbes's types — that shown in 
PI. XIII, fig. 4rt — really belongs to the same species as the examples illustrated in 
figs. 2 a and 3 a on the same plate. 



42 FOSSIL ASTEROIDEA. 



3, Metopastee Boweebankii, Forbes, sp. PI. XV, figs. 2 a — 2d; PI. XVI, figs. 

1 a— 1 d. 

GoNiASTEE (GoNiODiscTJs) BowEEBANKii, Forhes, 1848. Memoirs of the Geolo- 
gical Survey of Great Britain, 
vol. ii, p. 473. 

— — — Forhes, \S50. In Dixon's Geology and 

Possils of the Tertiary and 
Cretaceous Formations of 
Sussex, London, 4to, p. 333, 
pi. xxii, fig. 4. 

— — — Morris, 1854. Catalogue of British 

Fossils, 2nd ed., p. 81. 

AsTBOQONiUM BowEEBANKii, Dujardin and Supd, 1862. Hist. Nat. 

Zooph. Echin. (Suites a Buffon), 
p. 399. 

GoNiASTEE (GoNioDiscus) BowEEBABTKii, Forhes, 1878. In Dixon's Geology of 

Sussex (new edition, Joues), 
p. 366, pi. XXV, fig. 4. 

Body of medium or rather large size. General form depressed. Abactinal 
surface flat ; actinal surface also flat, or with a slight tendency to become convex. 
Marginal contour pentagonal, with a very small amount of lunation in the sides. 
Margin thick and well rounded. 

The supero-marginal plates are five in number counting from the median 
interradial line to the extremity, or ten from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. They 
form a broad border to the abactinal area of the disk of uniform breadth through- 
out, which measures about 8"5 mm. at the median interradial line in the type- 
specimen described by Foi'bes from the collection of the late Dr. Bowei'bank. 
Excepting the ultimate paired plate all the supero-marginal plates are of equal 
size. They are short and broad, the breadth being nearly twice and a half the 
length, the actual measurements in the type being length 3'5 mm. or a trifle more, 
and breadth 8*5 mm., in which case the dimensions are in the proportion of 7 : 17. 
The abactinal surface of the plates is slightly convex along the direction of the 
breadth, sufficient to define each plate distinctly. The general surface of the 
whole sei'ies is gently arched towards the margin adjacent to the infero-marginal 
plates. The height of the plates as seen in the margin is about 6 mm., and there 
is scarcely any or only the slightest diminution in height as the plates approach 



METOPASTER BOWERIUNKII. 43 

the extremity of the ray, and the ultimate paired plate is not prominent or gibbous 
abactinally. The whole superficies of the supcro-marginal plates is covered with 
small, widely spaced, equidistant, uniform punctations, and along the entire 
margin of the plate is a very narrow and deeply depressed border of fairly 
uniform l)readth, covered with much smaller and closely crowded punctations, 
upon which much smaller granules than those which occupied the central area of 
the plate were originally borne. One or two or even three small entrenched 
pedicellarije may be present on the central area of a plate, irregularly 
disposed. 

The ultimate paired plate is triangular in form as seen from above. The 
margin or side which represents its length and coincides with the margin of the 
disk measures a little more than once and a half or nearly twice the length of the 
adjacent supero-marginal plates ; and the margin representing the breadth of the 
plate which abuts on the penultimate suporo-marginal plate is shorter than the 
margin of the latter plate. The remaining side of the plate which touches the 
corresponding ultimate plate of the adjacent side of the disk, and falls in the 
median radial line of the disk, is sul)equal to or even slightly shorter than the 
breadth of the preceding marginal plates. The ultimate plate in this species is 
not elongated, and no prolongation beyond the normal pentagonal contour of the 
disk occurs in the extension of the median radial line. The surface of the ultimate 
plate is covered with punctations and margined with a finer and closely crowded 
series precisely similar to those on the other supero-marginal plates. 

The abactinal area of the disk within the boundary of the marginal plates is 
covered with small, subregular, hexagonal plates or paxillar tabulae, which have 
their surface marked with minute, low, subhemispherical, and closely placed 
miliary granulations, which do not, however, extend quite to the margins of the 
plates. A number of the plates bear in the centre a rather large entrenched 
pedicellaria, consisting of a central foramen and normally two lateral fossse, and 
there is usually a circular series of coalesced granules in which the fossae are 
included, which imparts a very characteristic appearance to the organ in this 
species (see PI. XVI, fig. 1 d). 

The following description of the characters of the actinal area of the disk of 
this species is taken from an example preserved in the Museum of Practical 
Geology, Jerrayn Street, and figures of which are given on PI. XV, figs. 2n — 2(1. 

The infero-marginal plates are eight in number counting from the median 
interradial line to the extremity, — that is to say, there are sixteen for the whole 
side of the disk, as against ten in the supero-marginal series. The length of the 
four innermost plates on each side of the median interradial line is slightly greater 
than that of the corresponding plates of the supero-marginal series ; and there 
are four infero-marginal plates much smaller than those preceding, corresjjonding 



44 FOSSIL ASTEROIDEA. 

to the ultimate supero-marginal plate. As seen in the lateral wall of the disk the 
heif^ht of the infero-marginal plates is slightly greater than that of the supero- 
marginal series. The breadth of these plates adjacent to the median interradial 
line on the actinal surface is 6 mm., or even a little more in an example whose 
major radius measures 37 mm. and the minor radius 27 mm. The breadth of the 
marginal border rapidly diminishes towards the extremity of the ray. The 
surface of the infero-marginal plates is ornamented with extremely small and 
closely crowded punctations, upon which traces of a minute, closely crowded, and 
uniform granulation are preserved here and there. 

The adambulacral plates are small, about twice as broad as long, and their 
surface is traversed by about three ridges, bearing punctures, running parallel to 
the ambulacral furrow, upon which the spinelets composing the adambulacral 
armature were articulated. There were about five or six spinelets in each lineal 
series. 

The mouth-plates are regularly triangular, about twice and a half as long as 
broad, and the two adjacent plates which constitute a pair form together a regular 
rhomboid or lozenge-shaped figure. Their surface is covered with small, crowded, 
rather coarse, irregularly disposed tubercles or granules (see PI. XV, fig. 2 d). 

The actinal intermediate plates are fairly large, and there is a distinct diminu- 
tion in size towards the outer margin of the disk adjacent to the marginal plates. 
The plates adjacent to the adambulacral plates are pentagonal, but a subhexagonal 
or polygonal form elsewhere is the rule, with comparatively little irregularity. 
The surface of the actinal intermediate plates is entirely covered with very small 
equidistant punctations, upon which a uniform close granulation was previously 
borne. Occasional small excavate pedicellarise are present here and there, the 
lateral fossEe being slightly curved. 

Dimensions. — The type specimen is unfortunately fragmentary, and the radial 
dimensions cannot be given. The length of one side of the disk, measured from 
the tip of one ray to the tip of the adjacent ray, is about 41 mm. ; the breadth of 
the supero-marginal plates adjacent to the median interradial line is 9 mm. ; and 
the thickness of the margin is about 12 mm. 

In the fine example preserved in the Museum of Practical Geology, Jermyn 
Street, figured on PL XV, fig. 2 a, the major radius measures 37 mm., and the 
minor radius 27 mm. ; the length of one side of the disk measured about 
42 mm., or probably rather more when complete ; the breadth of the infero- 
marginal plates adjacent to the median interradial line is G mm. ; and the 
thickness of the margin is 8'5 mm. 

Locality and Stratigraphical Position. — The type specimen is stated by Forbes 



METOPASTER ZONATUS. 45 

to have been obtained from the Upper Chalk of Kent, but no indication of locality 
is now preserved on the label. The example belonging to the Museum of 
Practical Geology is from the Upper Chalk of Gravesend. 

History. — The type of this species, which was described by Forbes in his 
memoir ' On the Asteriadge found fossil in British Strata ' (' Mem. Geol. Surv.,' 
vol. ii, p. 473, 1848), originally formed part of Dr. Bowerbank's Collection, and 
was first figured by Forbes in Dixon's ' Geology and Fossils of the Tertiary and 
Cretaceous Formations of Sussex,' London, 1850, pi. xxii, fig. 4. That specimen 
is now preserved in the British Museum, where it bears the register number 
" E 2578." An accurate drawing of the type is given on PI. XVI, fig. 1 a, of the 
present work. 



4. Metopasteb zonatps, Sladen. PL XII, figs. 2 a — 2 c. 

Body of small or medium size. General form depressed. Abactinal surface in 
the fossil condition, as at present known, essentially concave in consequence of 
the conspicuously upturned extremities of the rays. Actinal surface conformably 
convex. Marginal contour pentagonal, with the radial angles slightly produced 
and obtusely rounded, and the sides distinctly lunate. The major radius measures 
nearly one-half more than the minor radius, or in the proportion of 3 : 2 approxi- 
mately ; the actual dimensions in the example under notice being R := 27 mm., 
r := 19 mm. approximately. Margin very thick in relation to the size of the disk, 
and regularly rounded. 

The supero-marginal plates are four in number, counting from the median 
inteiTadial line to the extremity, or eight from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. They 
form a broad border to the abactinal surface of the disk, of uniform breadth 
throughout, which measures about 8 mm. at the median intcrradial lino, in an 
example whose minor radius measures 19 mm. Excepting the ultimate paired 
plate all the supero-marginal plates are subequal, the breadth being nearly three 
times the length, the actual measurements in the example under notice being 
length 2'75 — 3 mm., and breadth about 8 mm. The abactinal surface of the plates 
is distinctly convex along the median line of breadth, by which means each plate 
is conspicuously defined. The general surface of the whole supero-marginal 
series between the two ultimate plates is regularly rounded, and forms an uninter- 

7 



46 FOSSIL ASTEROIDEA. 

rupted regular curve between the adcentral margin of the plate and the margin 
in the lateral wall adjacent to the infero-marginal plates. The height of the 
plates as seen in the lateral view of the disk is greater than their length, and 
there is an apparent increase in height as the plates approach the extremity of 
the ray, the ultimate plate being still higher and distinctly tumid (see PI. XII, 
fig. 2 b). The whole superficies of the plates is covered with small, widely spaced, 
equidistant, uniform punctations ; and there is a narrow depressed border sur- 
rounding the margin of the plate with much smaller and closely crowded puncta- 
tions, upon which minute miliary granules were previously borne. 

The ultimate paired plate is much larger than any of the other supero-marginal 
plates, its length as measured on the outer margin being more than twice the 
length of the other supero-marginal plates. Its breadth is about equal to that of 
the adjacent supero-marginal plate. It is subtriangular in form as seen from 
above, and the line of junction with the corresponding companion plate of the 
adjacent side of the disk is complete throughout, and coincides with the median 
radial line. The convexity of the plate falls in a line parallel and adjacent to this 
margin of the plate, and its height is greatest there. From this convexity the 
surface slopes gradually and regularly in conformity to the curve of the superficies 
of the other supero-marginal plates. The actual dimensions of the ultimate plate 
in the example under notice are, length 7 mm., breadth 7 ram. ; greatest height as 
seen in the marginal view, about 8"5 mm. The surface of the ultimate plate is marked 
with a precisely similar ornamentation to that on the other supero-marginal plates. 

The odd terminal plate is very small, and though only traces are present in 
the type it is well preserved in other examples. It is prominent, cylindrical, and 
abruptly truncate, resembling in all respects the form described in Metopaster 
Parl'bisoni. 

The madreporiform body, which is only partially exposed in the example under 
notice, is apparently subtriangular in outline, and is marked with very fine centri- 
fugally radiating striations (see PI. XII, fig. 2 c). 

The infero-marginal plates ai'e seven in number, counting from the median 
interradial line to the extremity, — that is to say, there are fourteen for the whole 
side of the disk, as against eight in the supero-marginal series. The length of the 
three innermost plates on each side of the median interradial line is subequal to 
that of the superior series, but their height as seen in the marginal view of the 
disk is much greater, the thickness of the whole margin, i. e. both series of plates 
together, being 10 mm. in an example whose minor radius is 19 mm. Four plates 
underlie the superior ultimate plate, the last two being very small and triangular 
in form. All the four are adjacent to the adambulacral series of plates. The 
ornamentation or surface-marking of the infero-marginal plates is precisely 
similar to that of the supero-marginal series. 



METOPASTER UNCATUS. 47 

Dimensions. — In the example figured on PI. XII, fig. 2 a, the major radius is 
27 mm. and the minor radius about 19 mm., the thickness of the margin 10 mm. 

Locality and Strafigraphical Position. — The figured example is from the Upper 
Chalk near Bromley. A number of other examples of this species are in the 
collection of the British Museum, all from the Upper Chalk, and most of them 
from the same locality, the locality of the remainder being not recorded. 

Remarks. — I was at first somewhat in doubt as to whether to rank tliis form 
as a variety of Metopaster Farldnsoni, or as a distinct species. I have taken 
the latter course. Although there are many points of resemblance in general 
structure, as well as in various details when considered independently, the facies 
of this form is so distinct from that of Metopaster Parhinsoni, and is so readily 
recognisable, that there seems to me full justification for considering Mctupaster 
zonati's specifically distinct. The great breadth of the supero-marginal plates as 
compared with their length, the form and character of the ultimate plates, the 
great thickness of the margin, and the relative proportions of the marginal plates, 
as well as the general habit of the abactinal surface, apart either from the 
individual characteristics of the plates independently or from other special details, 
are amply sufficient to distinguish the form from its nearest ally, Metopaster 
Parkinsoni. 



5, Metopastee unoatus, Forbes, sp. PI. XI, figs. 3 o, 3 6 ; PL XIV, figs. 1 a — 3 ; 

PI. XV, figs. 1 a, 1 h. 

GoNiASTEE (GoNiODlscus) UHCATU8, Forbes, 18-tS. Memoirs of the Geological 

Survey of Great Britain, vol. ii, 
p. 4.72. 

— — — Forbes, 1S50. In Dixon's Geology and 

Fossils of the Tertiary and Creta- 
ceous Formations of Sussex, London, 
4to, p. 331, pi. xxi, fifjs. 4, 5, 8. 

— — — Morris, lS5-t. Catalogue of British Fossils, 

2nd ed., p. 81. 
AsTHOOONTUM xmCATTJM, Dujardin and Htipf, 18G2. llisl. Nat. Zoopb. 

Eehin. (Suites a Buffou), p. 399. 
GoNiASTEB (GoNiODiscus) UNCATUS, Forbes, 1878. In Dixon's Geology of Sussex 

(new edition, Jones), p. 305, pi. xxiv, 

figs. 4. 5, 8. 



48 FOSSIL ASTEROIDEA. 

Body rather small, or at most only of medium size. General form depressed. 
Abactinal surface flat, or with a tendency for the rays to be slightly directed 
upward at the extremities. Actinal surface slightly convex. Marginal contour 
pentagonal, with the sides slightly lunate, though the curvature is often more or 
less flattened; the extremity of the rays is only slightly produced. The major 
radius measures about one-third more than the minor radius, the major dimension 
being proportionately rather greater in large tests than in small ones. The 
margin is thick, and the lateral wall has more of a precipitous than a rounded 
character, although the infero-marginal plates are well rounded on the actinal 
surface. 

The supero-marginal plates are three in number, counting from the median 
interradial line to the extremity, or six from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. They 
form a broad border to the abactinal area of the disk, of uniform breadth through- 
out, which measures about 7 mm. at the median interradial line in an example 
whose major radius measures 36'5 mm. and minor radius 27 mm. (PI. XIV, fig. 2 a). 
Excepting the ultimate paired plates, the four intermediate supero-marginal plates on 
each side of the disk are of equal size, the breadth being about once and a half the 
length, the actual measurements in the specimen under notice being length 5 mm., 
and breadth 7 mm. The abactinal surface of these plates is tumidly convex, while 
the lateral wall is plane and vertical, and the abactinal tumidity commences 
abruptly at a little distance from the adcentral margin of the plate, which leaves a 
small level area at the rounded end of the plate abutting on the abactinal plates or 
paxillar tabulas. On the surface of this level band near the adcentral margin, and 
forming a more or less definite series running parallel to it, are three or four 
irregular tubercular eminences or granules, but very indistinct and more or less 
weatherworn (see PI. XIV, fig. 2 c). The entire margin of the plate is surrounded 
by a very narrow depressed border, with very fine, closely crowded, uniserially 
disposed punctations, upon which a small miliary granulation was previously borne. 
The whole general superficies of the plate is smooth and weatherworn in every 
example I have seen. The height of the plates as seen in the margin is as great 
as or even slightly greater than their length, and the prominently tumid character 
of the plates abactinally causes them to appear in the lateral view somewhat like 
truncate cones abruptly rounded (see PI. XIV, fig. 2 b). 

The ultimate paired plate is larger and longer than any of the other plates, 
and is of a diiferent and very peculiar shape. It is subtriangular in form as seen 
from above, produced and pointed at the extremity, and to a certain extent recalls 
the form of a ploughshare or coulter in consequence of a peculiar nipped-in 
appearance caused by the extension of a tumid region which runs parallel to the 



METOPASTER UNCATUS. 49 

outer margin and rises abruptly from a level area which occupies the inner half of 
the plate along the margin touching the corresponding plate of the adjacent ray, 
— the line of junction of the two plates coinciding with the median radial line. 
The length of the ultimate plate is nearly twice that of the other marginal plates, 
measuring 9'25 mm. in an example whose major radius is 36*5 mm. and minor 
radius 27 mm. As seen in the marginal view of the test, the ultimate is not 
higher or more tumid than the other marginal plates (see PI. XIV, fig. 2 b). The 
outer margin of the ultimate plate has a slight concave curvature, and the inner 
margin adjacent to the corresponding plate is curved convexly towards the 
proximal end of the plate. In consequence of this rounding the two ultimate 
plates in a pair do not unite throughout their entire length, but are separated by 
a small notch at the end of the suture adjacent to the abactinal paxillar area of 
the disk. On the small level area of the ultimate plate are a numljer of small 
irregular tubercular eminences ; four or five larger than the others form a sort of 
series parallel to the rounded mai'giu, and a longitudinal series of eight or nine 
much smaller miliary granules run along the flank of the longitudinal tumidity of 
the plate ; and several additional granules of intermediate size may be present in 
the space between the two series just described. Excepting these granules, the 
surface of the ultimate plate is smooth like that of the other supero-marginal plates. 

The abactinal area of the disk witliin the boundary of the marginal plates is 
covered with small subregular plates or paxillar tabulae, an hexagonal form predomi- 
nating. The plates in the median interradial areas are much larger than the other 
plates on the disk, and a marked diminution in size in all the plates takes place as 
they approach the margin. All the plates have their surface marked with a very 
fine granulation. Small entrenched pedicellaritie are occasionally present, but 
there appear to have been very few. 

The primary basal plates are larger than any of the other abactinal plates. 
They are well seen in an example from the Upper Chalk of Kent, in which the 
inner side of the abactinal wall is exposed by the removal of the actinal floor and 
ambulacral plates. This specimen, which is preserved in the British Museum, and 
bears the registration number " 35,496," is drawn on PL XI, fig. 3 a. The 
example in question is further interesting in showing that the plates of the radial 
regions have stellate bases, whereas the larger plates of the interradial regions are 
sharply hexagonal, and fit closely to their adjacent plates (see fig. 3 h). 

The madreporiform body is very small, and is subsagittiform or irregularly 
lozenge-shaped in outline ; in the example under notice it is embedded, all except 
two straight sides, in one large adcentrally placed basal plate (see PI. XIV, 
fig. 2 (1) ; the two straight sides are bounded each by one largo plate. The 
surface of the madreporite is sculptured by very fine striations, which though 
more or less wavy are directed subparallel to the adceutral sides of the body. 



50 FOSSIL ASTEROIDEA. 

The position of the madreporite is nearer the centre of the disk than the 
margin. 

The infero-marginal plates are six in number, counting from the median inter- 
radial line to the extremity, — that is to say, there are twelve for the whole side of 
the disk, as against six in the supero-raarginal series. The length of the two 
innermost plates on each side of the median interradial line is subequal to that of 
the superior series, but the four succeeding infero-marginal plates are much shorter, 
and together correspond to the large ultimate supero-marginal plate. As seen in the 
lateral wall of the disk the height of the infero-marginal plates is very little more 
than one-half that of the superior series, the actual proportion in the specimen 
under notice being less than three-fifths. The breadth of the plates adjacent to 
the median interradial line on the actinal surface is 7*5 mm. in an example whose 
major radius measures 25 mm. and the minor radius 20 mm. The breadth of the 
marginal border diminishes so rapidly on each side of the median interradial line 
towards the extremities of the rays that the inner margin of the series of infero- 
marginal plates of each side of the disk is practically a sector of a circle. The 
surface of the plates is marked with small widely spaced punctations, and there is 
a narrow depressed border round the entire margin of the plate which is very finely 
punctate ; the border is broader at the adcentral end of the plate and the adjacent 
corners than elsewhere. 

The adambulacral plates are small, broader than long, and their surface is 
marked with about three oblique series, and an outer irregular group of fine 
punctations upon which the spinelets composing the armature of the plates were 
articulated. There are about six punctations in the innermost ridge or series 
adjacent to the ambulacral furrow. A few spinelets are still preserved in an 
example from the Upper Chalk near Bromley, from which this description is taken, 
which is in the British Museum collection, and bears the registration number, 
" B 2613." The spinelets are cylindrical, truncated, and do not appear to taper ; 
and their length is about equal to the length of the plates. 

The actinal intermediate plates are rhomboid and hexagonal or polygonal in 
form, and their surface is entirely covered with small equidistant punctations, 
upon which small uniform granules were previously attached. Remains of this 
granulation are occasionally to be found preserved in siUi, and may be seen in the 
example referred to in the preceding paragraph. Small entrenched pedicellarisB 
are occasionally present on the actinal intermediate plates. 

Dimensions. — The example figured on PL XTV, fig. 2 a, has a major radius of 
36-5 mm. and a minor radius of 27 mm. The length of the side is about 40 mm. 
Another specimen, shown in fig. 1 a on the same plate, is rather larger, the length 
of the side being about 45 mm. Much displacement of the plates has occurred in 



METOPASTER SUBLUNATUS. 51 

this fossil, and the radial dimensions can only be calculated approximately. The 
specimen figured by Forbes, which I have unfortunately not been able to trace, is 
smaller than either of the above. The drawing represents a test with the major 
radius measuring about 25 mm., the minor radius 20 mm., and the length of the 
side about 28 mm. The figure of the actiual aspect of this example is reproduced 
on PL XIV, fig. 3, of this memoir. 

Localifi/ and StratuirajMcal Position. — This is a well-known Upper-Chalk form. 
It is recorded by Forbes from Kent, Sussex, and Wiltshire. Specimens in the 
British Museum bear the localities of Charlton, Gravesend, Bromley, and 
« Kent." 

History. — This species, primarily described by Forbes in his memoir ' On the 
Asteriadae found fossil in British Strata,' was first figured in Dixon's ' Geology 
and Fossils of the Tertiary and Cretaceous Formations of Sussex,' London, 1850. 
The example which I consider must undoubtedly have been the type (Dixon, 
pi. xxi, figs. 4 and 5) I have hitherto unfortunately not been able to find. It is 
stated by Forbes to have formed part of the late Mr. Pearce's collection, and to 
have been obtained from the Wiltshire Chalk. A badly drawn fragment (Dixon, 
pi. xxi, fig. 8) is preserved in the British Museum, but I do not consider it to be 
correctly referred to this species. In my opmion it belongs to a distinct species, 
Metojiaster cingulatus, of which a description is given at p. 53. 

The examples of this species which have been drawn on PI. XIV are preserved 
in the British Museum. 



6. Metopaster SUBLUNATUS, Forbes, sp. 

GoNiASTEE (GoNiODiscus) SUBLUNATUS, Forbes, 1848. Memoirs of the Geological 

Survey of Great Britaia, vol. ii, 
p. 472. 

— — — Forbes, 1850. In Bison's Geology and 

Fossils of the Tertiary and Cretace- 
ous Formations of Susses, London, 
4to, p. 331. 

— — — Morris, 1854. Catalogue of British Fos- 

sils, 2nd ed., p. 81. 
AsTBOGONlUM SUBLUNATUM, Dujarditi and IIiipc, 1862. Hist. Nat. 

Zooph. Echin. (Suites a Buffon), 

p. 399. 
GoNiASTEB (GoxioDiscus) SUBLUNATUS, Forbes, 1878. In Dison's Geology of 

Sussex (new edition, Jones), 

p. 365. 



52 FOSSIL ASTEROIDEA. 

This species was described by the late Professor Edward Forbes in Dixon's 
' Geology of Sussex ' in 1850 in the following words : 

" Body pentagonal, with gently lunated sides. Superior intermediate marginal 
plates four, nearly equal, plain, smooth, or minutely punctate. Inferiors similar. 
Superior oculars mitrate, large, triangular, acuminated. Ossicula of disc punc- 
tate. 

" Easily distinguished from the last species [imcahis] by its flattened mar- 
ginals and from the next [Hunteri] by its lunated sides. 

" Mus. Bowerbank, from the white chalk ; also in the collection of the 
Geological Survey" (op. cit., p. 331). 

No figure of the species has ever been published, and no record exists as to 
the specimen or specimens seen or used by Forbes as type. I have been unable to 
find any example from the Bowerbank Collection to which this name has been or can 
be applied; and the only examples which I have seen referred to this species at all 
are four fragmentary specimens now preserved in the Museum of the Geological 
Survey in Jermyn Street, and not more than two of these could have been in that 
collection in 1850. 

After a careful study of these specimens I am bound to confess that 1 find no 
character by which they can be separated from Metoimster uncatus ; and if the 
diagnosis is correct I am led to consider that I have certainly not seen Forbes's 
type. The sw^ero-marginal plates in the specimens in question are not flattened, 
and cannot be said to differ in character from those of Metopaster tmcatus. 

A possible explanation suggests itself in the supposition that Forbes inad- 
vertently mistook the actinal for the abactinal surface of the disk, a mistake which 
might easily be made by a less careful observer than the author of this species 
when dealing with a badly preserved fragment. If, however, what is really the 
actinal surface has been described as the abactinal surface the difficulty is prac- 
tically solved, for the infero-marginal plates in the fragments under notice are 
" plain, smooth, or minutely punctate." That this is not an improbable explanation 
I would submit the following facts : — (1) that in the original diagnosis of 1848^ 
Forbes states that the infero-marginal plates are unknown ; (2) that in the 
diagnosis of 1850, given above, the infero-marginal plates are stated to be 
" similar " (to the supero-marginals) ; and (3) that notwithstanding these state- 
ments all the examples in the Geological Survey Collection are essentially actinal 
presentments of the disk, and therefore the infero-marginal plates are the plates 

1 The following is the diagnosis iu full : — " G. corpore pentagonali, lateribus lunatis ; ossiculis 
lateralihus superioribus 4, subsequalibus, planis, minutissime punctatis ; inferioribus ? Ossiculis 
oeularihus superiorihus magnis, triaugularibus, mitratiB, tumidis, acuminatis." (' Mem. Geological 
Survey of Great Britain,' vol. ii, p. 472.) 



METOPASTER CINGULATUS. 53 

conspicuously available for description. To my mind it follows with little doubt 
either that Forbes has described the infero-marginal plates as supero-marginals, 
or else that I have not seen his type specimens. 

With my reverence for all tliat Forbes has written I prefer to leave the species 
as described by him, together with the record of these remarks, rather than strike 
a ruthless pen through any species created by so careful and accurate a worker. 
Time will pronounce the verdict. 

I consider it quite unnecessary to figure any of the fragments, here referred to, as 
being in the Jermyn Street Collection. The differences they present as compared 
witli a series of Metopaster uncatas do not in my opinion amount to even varietal rank, 
and arc confined to the slightly less developed tumidity of the abactiual surface of 
the supero-marginal plates, and to the external contour of the mitrate ultimate paired 
supero-marginal plates, which is slightly convex marginally rather than incurved 
to produce the characteristically claw-shaped form of Metopaster uncatus. These 
are, in my opinion, merely individual diff'erences. 



7. Metopaster cingulatds, Sladen. PL XIV, figs. 4 a — 4 d. 

Body of small size. General form depressed. Abactinal surface slightly 
concave, actinal surface flat. Marginal contour pentagonal, with the sides slightly 
lunate. The rays are not produced beyond the contour of a true pentagon, and 
the radial angles are not rounded. The_ major radius is proportional to the minor 
radius as 100 : 77"5, the actual dimensions in the example described being, major 
radius 20 mm., minor radius 15-.5 mm , approximately. The margin is thick, and 
though well rounded has more or less of a precipitous character. 

The supero-marginal plates are three in number, counting from the median 
interradial Une to the extremity, or six from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. They 
form a broad border to the abactinal area of the disk of uniform breadth through- 
out, which measures about 6-5 mm. at the median interradial Une in an example 
whose diameter (R -|- r) measures from about 36 mm. to 37 mm. 

Excepting the ultimate paired plates, the four intermediate supero-marginal 
plates on each side of the disk are approximately equal in size, the breadth being 
more than twice and a half the length, the actual dimensions in the example under 
notice being length 2-25 mm., and breadth 6-5 mm., in the plate adjacent to the 
median interradial Ime. The abactinal surface of these plates is distinctly 
tumid, a subtubercular eminence rising in the median third of the abactinal area 
of the plate. The slope of the tumidity descends gradually on the outer side, and 

8 



54 FOSSIL ASTEROIDEA. 

merges in the rounding of the high lateral wall of the plate. On the level area 
o£ the plate, which is consequently the inner or adcentral part of the surface, are 
several low tubercular eminences of irregular shape and disposition, but which 
appear to assume a more or less distinct biserial arrangement at right angles to 
the adcentral margin of the plate. They appear to be enlarged irregular granules, 
and in all the examples I have examined they have become to a certain extent 
ill-defined, owing either to growth or to weather-wearing. The general character 
of the ornamentation is shown in PL XIV, fig. 4 c. The entire margin of the 
plate is surrounded by a very narrow depressed border, which is very minutely 
punctate, probably only in a single lineal series. The general superficies of the 
plate beyond the ornamentation mentioned is smooth, as if weatherworn, in all 
the examples I have seen, but in some specimens there appear to be traces of a 
more or less granulous character, and in some instances suggest the impression 
that an ornamentation similar to that noticed in Mitraster rugatus was probably 
present on at least a part of the surface of the plate. The height of the supero- 
marginal plates as seen in the margin is greater than their length, and their 
prominent abactinal tumidity has a distinctly conical character from this point 
of view. 

The ultimate paired plate is fully twice as long as the other supero- marginal 
plates measured on the outer margin, and its breadth is equal to that of the 
adjacent supero-marginal. It is triangular in form, and the line of junction with 
the companion ultimate plate of the adjacent side coincides with the median 
radial line. The actual dimensions in the example under description are, length 
6'2 mm., breadth about 6 mm. As seen in the lateral view of the disk the 
ultimate plates are distinctly tumid abactinally (see PI. XIV, fig. 4 6). The 
abactinal surface of the plate is ornamented by a number of miliary tubercles or 
granules, more or less serially disposed parallel to the margin adjacent to the 
companion plate, and more numerous at the adcentral end of that margin. 
Beyond this the surface of the ultimate plate is smooth, like that of the other 
supero-marginal plates. 

The abactinal area of the disk within the boundary of the marginal plates is 
covered with hexagonal or polygonal plates or paxillar tabulas, which are small in 
size generally, excepting the primary apical plates, which are comparatively very 
large. All the plates have their surface covered with a fine, uniform granulation. 
The primary apical plates have a small central area of low elevation, not higher 
than if a number of granules had become coalesced — the structure being sugges- 
tive of a tubercle in process of disappearance, — in other words, the scar left by a 
tubercle which had existed in an earlier stage of growth (see PI. XIV, fig. 4(Z). 

Dimensions. — The example figured on PI. XIV, fig. 4 a, has the following 



METOPASTER CORNUTUS. 55 

measurements : — major radius, 20 mm. ; minor radius, 15"5 mm ; length of the 
side, about 22 mm. The thickness of the margin is 7 mm. in a specimen whose 
side is 23 "5 mm. 

Locality and Stratigraphical Position. — The specimen described above and 
figured on PI. XIV, fig. 4 a, is from the Upper Chalk, near Bromley. It is 
preserved in the British Museum, and bears the register-number " 46,770." Other 
examples which I refer to the same species are also in the National Collection, 
and one, if not more, was obtained from the same locality. 

Bemarls. — A fragmentary example which was figured in Dixon's ' Geology and 
Fossils of the Tertiary and Cretaceous Formations of Sussex,' pi. xxi, fig. 8, and 
was referred by Forbes to Goniaster (Goniodiscns) uncatus, now forms part of the 
collection in the British Museum, and bears the registered number " E 2577." 
This specimen appears to me to belong to the present species, and not to the true 
Metopaster uncatus. I can scarcely think that Forbes would have intentionally 
ranked the two forms as belonging to one species, and I have not thought it 
needful on the sole grounds of this fragment having been figured to regard 
Metopaster cingulatus as a dismemberment of Forbes' Metopaster uncatus. 

Metopaster cingulatus is readily distinguished from Metopaster uncatus by its 
very short broad supero-marginal plates, by their more limited and more conical 
tumidity, by their greater height as seen in the margin, as well as by their 
difi'erent ornamentation. The ultimate plates are triangular, and do not present 
the peculiar form characteristic of Metopaster uncatus. In many respects 
Metopaster cingulatus appears to hold an intermediate position between Mitraster 
rugatus and Metopaster uncatus. 



8. Metopaster cobndtds, Sladen. PI. XIV, figs. 5 a — 5 d. 

Body of small size. General form depressed. Abactinal surface slightly 
concave, the extremity of the rays being directed slightly upward. Actinal surface 
slightly convex. Marginal contour pentagonal, with the sides slightly lunate 
and the extremity of the rays slightly produced. The major radius is proportional 
to the minor radius as 100 : 74, the actual dimensions in the example described 
being, major radius about 19 mm., minor radius about 14 mm. approximately. 
The length of the side is 22*5 mm. The margin is moderately thick and 
apparently well rounded. 



56 FOSSIL ASTEROIDEA. 

The supero-marginal plates are only two in number, counting from the median 
interradial line to the extremity, or four from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. They 
form a broad border to the abactinal area of the disk. The supero-margiual plate 
adjacent to the median interradial line is broader than long, the dimensions in 
the example described being length about 3"25 mm., and breadth about 5"75 mm. 
The abactinal surface of this plate is slightly convex in the median line of 
breadth. The entire margin of the plate is surrounded by a very narrow 
depressed border with very minute punctations, closely crowded and uniserially 
disposed near the inner edge of the border, upon which a small miliary granulation 
was previously borne. The general superficies of the plate is covered with minute 
punctations irregularly disposed. The height of the two intermediate supero- 
marginal plates as seen in the lateral view of the margin (PL XIV, fig. 5 b) is 
scarcely half their length, and is less than half the height of the underlying infero- 
marginal plates. 

The ultimate paired plate is very much larger than the small intermediate 
plate just described, being nearly three times as long, the actual measurement 
being about 9*25 mm. in the example under notice. It is of a peculiar form, being 
shaped somewhat like an irregularly formed elytron of an insect as seen from 
above, the proximal margin being truncate where it joins the companion inter- 
mediate plate, and the distal extremity obtusely rounded (PL XIV, fig. 5 c). At 
a point situated three-fourths of the distance from the proximal to the distal 
extremity rises an abrupt truncate teat-like eminence. The peculiar form of the 
plate as seen in the lateral view of the margin and the character of the eminence 
just described will be better appreciated by reference to PL XIV, fig. 5 d, than by 
verbal description. The superficies of the ultimate plate is studded with rather 
widely spaced punctations disposed in groups, which do not extend over the whole 
of the area which falls in the lateral wall of the disk. As seen in the marginal 
view of the test the ultimate is very much higher than the intermediate marginal 
plates (see PL XIV, fig. 5 b). 

The odd terminal plate is unknown to me, no trace being preserved in the 
example under notice. 

In like manner the whole of the abactinal plating within the boundary of the 
supero-marginal plates has been removed, excepting only a few isolated fragments 
of plates out of position. 

The infero-marginal plates are large and high. Four are preserved between 
the median interradial line and the extremity, but the series is incomplete, 
probably one or more being wanting at the distal end of the series. This would 
increase the number eight now preserved on the whole side to ten or perhaps 
twelve. The two infero-marginal plates on each side of the median interradial 



MITRASTER. 57 

line are mucli larger and higher than the other plates. The plate adjacent to the 
median interradial line measures about 4 mm. in length and 4 mm. in height ; 
the next plate 5 mm. in lengtli, and from 3"5 mm. to 3'75 mm. in height. The 
surface of the plates is marked with small widely spaced punctatious, and there is 
a narrow depressed border round the entire margin of the plate, which is very 
finely punctate. 

The actinal area is unknown to me. 

Hisfori/. — The fossil delineated on PI. XIV, fig. 5 a, was drawn by Mr. A. H. 
Searle under Dr. Wright's instructions, but I regret that I have not been able to 
find any trace of the specimen. I am therefore led to believe that the type 
belonged to Dr. Wright's private collection, which has been distributed since his 
lamented death. Knowing by experience the extreme care and fidelity which 
characterise all Mr. Searle's work, I have ventured to describe the species from 
his drawings alone, for it seemed undesirable to leave such an interesting form 
without notice ; and I am hopeful that the publication of the figure and the 
description of its characteristic features will lead to the detection of the type. I 
am unable to give any information as to the locality or stratigraphical position 
from which the fossil was obtained. 

Bemarlca. — The rather small size of this example and the small number of 
supero-marginal plates — only four for the whole side of the disk — would not 
unnaturally suggest at first sight that this was possibly an immature form. After 
careful study, however, I do not consider such to be the case, or at any rate I am 
unable to regard the fossil under notice as the young of any of the species with 
which I am acquainted. The large and characteristically developed ultimate 
supero-marginal plates in conjunction with the presence of a normal number of 
infero-marginal plates, together with the fact that the size of the test is not less 
than that of another perfectly characterised species, lead me to rank this as a 
distinct species with little hesitation. The general proportions as well as the 
character of the different plates, and the facies of the form as a whole, appear to 
me to fully warrant this view. 



Gemts— MITRASTER, Sladen. 

(iliTpa = a broad belt, or girdle.) 

Body depressed and cycloid, or cyclo-pcntagonoid in contour. Marginal plates 
with co-ordinated granulose elevations and punctations, and a surrounding narrow 



58 FOSSIL ASTEROIDEA. 

depressed border with very minute punctations for the articulation of setae. 
Supero-marginal plates few in number and all subequal in size, forming a broad 
uniform border to the disk. Abactinal area covered with polygonal plates, some 
of which may have stellate or substellate bases, and upon the tabulae are borne 
small, more or less co-ordinated granules. Infero-marginal plates more numerous 
than the supero-marginal series, and decreasing in size as they approach the 
extremity ; the surface marked with punctations, which may be co-ordinated in a 
similar manner to that of those on the supero-marginal series, and may be associated 
with granulose elevations. Actinal intermediate plates small, polygonal, covered 
with uniform, crowded, shallow punctations, upon which granules were originally 
borne. Armature of the adambulacral plates arranged in longitudinal lines, which 
may be slightly oblique. Small entrenched pedicellarise may be present occasion- 
ally on the actinal intermediate plates. 

Mitraster is characterised by its cycloid contour, by the equality in size of the 
supero-mai-ginal plates, which do not diminish towards the extremity, and by the 
character of the ornamentation of the marginal plates, especially of the superior 
series. 

The main characters which distinguish this and the two preceding genera are 
distinctly relative, and may be here conveniently compared. In Pentagonaster the 
rays are more or less produced, the supero-marginal plates are more or less 
numerous, and decrease in size as they approach the extremity of the ray, 
and are devoid of a marginal border of setae. In Meto-paster the rays are very 
slightly produced, the contour being pentagonal and only slightly extended. 
The supero-marginal plates are few in number, and do not decrease in size as they 
approach the extremity, the ultimate paired plate being larger than the others. 
All are furnished with a marginal border of setse. In Mitraster the contour 
is cycloid almost to the obliteration of the pentagonal form. The supero-marginal 
plates are few in number, but neither decrease nor diminish in size, being subequal 
throughout ; and they are furnished with a marginal border of setae. 

I consider that these differences indicate structural characters of sufficient 
morphological significance to render the forms presenting them worthy of recog- 
nition as distinct genera. 



MITRASTER HUNTERI. 59 



1. MiTEASTER HuNTEEi, Forbes, sp. PI. IX, figs. 3 ft— 3 e -, PI. XII, figs. 3 a — 3 e ; 

PI. XV, figs. 3 a— 5 b. 

GoNiASTEU EEOULABis, Mantell, 1844. Medals of Creation, vol. i, 

p. 335, lign. 73 (non Linck). 

GoNiASTEE (GoNiODiscus) HuNXKBi, Forbes, 1848. Memoirs of the Geological 

Survey of Great Britain, vol. ii, 
p. 471. 

— — — Forbes, 1850. In Dixon's Geology and 

Fossils of the Tertiary and Creta- 
ceous Formations of Sussex, 
London, 4to, p. 331, pi. xzi, fig. 1. 

— — — Morris, 1854. Catalogue of British Fossils, 

2nd ed., p. 81. 
AsTHOGONiUM HuNTEEi, Dujardtn and Hupi, 1862. Hist. Nat. 

Zooph. Echin. (Suites a Buffon), 

p. 399. 
GoNiASTEK (GoNiODiscus) HuNTEEi, Forbes, 1878. In Dixon's Geology of Sussex 

(new edition, Jones), p. 365, 

pi. xxiv, fig. 1. 

Body of small size. General form depressed. Abactinal surface flat and 
apparently depressed within the boundary of the supero-marginal plates, the 
gibbosity of the latter and their centrally sloping surface giving a concave character 
to the area generally in fossil examples, which was probably always more or less 
present. Actinal surface flat or with a tendency to be sliglitly convex. Marginal 
contour subcircularly pentagonoid, the sides being sliglitly convex or bulging out- 
ward. The major radius is proportional to the minor radius as 100 : 90"47 approxi- 
mately ; and the rays are not produced, the angles of the pentagon being obtusely 
rounded. Margin thick and well rounded, the slope being more gradual on the 
actinal surface. 

The supero-marginal plates are three in number counting from the median 
interradial line to the extremity, or six from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. They 
form a broad border to the abactinal area of the disk, of uniform breadth through- 
out, which measures about 6*3 mm. at the median inten-adial line in an example 
whose diameter (R -\- r) measures about 40 mm. Excepting the ultimate plates 
all the supero-marginal plates are of equal size and uniform, tlio breadth being 
a little more than once and a half the length, the actual measurements in the 



60 FOSSIL ASTEROIDEA. 

specimen under notice being length 4 mm. and breadth 6*3 mm., in the plate 
adjacent to the median interradial line. The length of the plate at the end which 
falls in the margin of the disk is a shade greater than the adcentral or inner end, 
and the plates are consequently faintly wedge-shaped, but so slightly that the 
character is scarcely noticed at first sight. The ultimate plates, however, are 
distinctly wedge-shaped, the length at the outer margin being a little greater 
than that of the other marginal plates, while the length of the inner end is rather 
less — often not more than one-half the lens^th of the same end in the other plates. 
The breadth of the ultimate plates is the same as that of all the supero-marginal 
plates ; and the corresponding plates of the two adjacent sides touch one another 
throughout, the line of junction falling in the median line of the ray. The abactinal 
surface of the plates is distinctly convex, and the character is more conspicuously 
emphasised by the plate becoming rapidly gibbous on the outer half, the outer 
side of the eminence forming the rapid bend to the lateral wall of the plate. 
The height of the plates as seen in the margin is usually equal to, or even 
rather greater than their length, but may occasionally be less. There is no 
diminution in height as the plates approach the extremity of the ray, and the 
ultimate paired plate has a tendency to appear even a trifle higher and more 
gibbous than the others, but the character is derived probably more from the 
position in which the plate sometimes is than fi'om an actual increase in size or 
gibbosity. The abactinal surface of the plates is covered with coarse tuberculiform 
mammillations which gradually die out before reaching the apex of the gibbosity. 
In the interspaces between the eminences are small, more or less widely spaced 
punctations, and these extend over the whole surface of the plate, and are 
consequently present on the outer portions as well as on the lateral wall. There 
is a narrow depressed border round the entire margin of the plate, which is very 
minutely punctate (see PI. XII, fig. 3 c). In smaller examples there often appears 
to be only one or two rows of punctations. The ornamentation of the ultimate 
paired plates is precisely similar to that on the other supero-marginal plates. 

The odd terminal or " ocular" plate is very small, and, so far as I can make 
out, resembles superficially a short truncated cylinder which protrudes somewhat 
cannon-like from a small triangular space left by the ultimate paired plates similar 
to what I have already described in Metopader. 

The abactinal area of the disk within the boundaiy of the marginal plates is 
covered with comparatively large polygonal plates, with closely crowded, rather 
coarse, uniform granulations, upon which miliary granules or spinelets were 
previously borne. The primary apical plates are remarkably large, and the plates 
in the interradial areas are larger than the plates in the radial areas. Of the 
plates in the radial areas at least the median series and two series on each side 
have bases of a six-rayed, substellate form. These are admirably seen in an 



MITRASTER HUNTERI. 61 

example preserved in the British iluseum bearing the register-number " 46,772," 
in nhicb the inner surface of the abactinal floor is exposed. 

The madreporiform body, in the examples in which I have detected its 
presence, appears to be small and subtriangular, and is marked with very coarse 
striations. 

The infero-marginal plates are five in number, counting from the median inter- 
radial line to the extremity, — that is to say, there are ten for the whole side of the 
disk as against six in the supero-marginal series. The length of the two innermost 
plates on each side of the median interradial line is a little greater than that of 
the corresponding superior plates ; the breadth of the plate adjacent to the 
median interradial line is 7 mm. in the specimen bearing the British Museum 
register-number " 46,766," and is a little greater than the breadth of the corre- 
sponding superior plate as seen in the example bearing the British Museum register 
number " E 2583." 

The second plate, counting from the median interradial line, is a little less 
broad, and the third is slightly more diminished in breadth, and its adcentral 
margin merges with a sweeping curve into the lateral distal margin, which gives 
the plate a more or less cuneiform shape. A large portion of the distal lateral 
margin of this plate abuts on the adambulacral plates. The fourth infero-marginal 
plate is very small and triangular in form, with the apex directed adcentrally, 
and with one side abutting entirely on the adambulacral plates. The fifth plate is 
smaller still. In consequence of the triangular shape of the fourth and fifth 
plates the greatest length of the third plate is opposite the apex of the fourth 
plate, and the length of the third plate gradually diminishes up to the outer 
margin. The breadth of the third plate is 5*6 mm., and that of the fourth plate 
is only 3'2 mm. 

The surface of the infero-marginal plates, which is more or less jilain, is orna- 
mented with small, widely spaced, and more or less equidistant punctations, and 
there is no trace of the tubercular mammillation present on the surface of the 
supero-marginal plates. On the inner third of the plate the punctations are more 
closely placed, and they have the appearance of falling into a more or less 
distinct reticulated arrangement (see PI. XII, fig. 3 d). A narrow depressed 
border surrounds the entire margin of each plate, which is very minutely 
punctate. 

The adambulacral plates, wliich are small, are broader than long, and have 
their surface traversed by several ridges placed slightly obliquely, but I am unable 
to define the armature. 

The actinal intermediate plates, which are somewhat large in relation to the 
size of the disk, are rhomboid or polygonal in outline. Their surface is covered 
with small, closely crowded, uniform pits, upon which miliary granules or spinelets 

9 



62 FOSSIL ASTEROIDEA. 

were previously borne (see PI. XII, fig. 3 e). A small entrenclied pedicellaria may 
be present on an occasional plate here and there. 

Dimensions. — The example figured on PI. XII, fig. 3 a, has a major radius of 
about 30 mm., and a minor radius of about 28 mm. The length of the side is about 
36 mm. The thickness of the margin is about 10 mm. In the specimen given on 
PI. XV, fig. 4 a, the major radius measures 21 mm., and the minor radius 19 mm. 
approximately. The length of the side is about 25 mm. 

Locality and Stratigra^yhical Position. — This species is a characteristic Upper 
Chalk form. The majority of examples are from Kent and Sussex. A fine series 
from Bi'omley is preserved in the British Museum. 

History. — This species was referred to by Dr. Mantell under the name of 
Goniaster regularis. The specific name was, however, already preoccupied — at 
least in literature — for an existing starfish ; and although the latter is not now 
recognisable, no doubt can possibly exist that Mantell's fossil species is certainly 
a different thing from the starfish to which Linck gave the name of Pentagonaster 
regularis. 

Forbes was the first to describe the species under the name of Goniaster 
{Goniodiscus) Hunteri, and his type-specimen, which is figured in Dixon's ' Geology 
and Fossils of the Tertiary and Cretaceous Formations of Sussex,' pi. xxi, fig. 1 , 
formed part of John Hunter's Collection, now preserved in the Museum of the 
Royal College of Surgeons. The examples, illustrated in the present work are all 
preserved in the British Museum. 

Variation. — There are at least two well-preserved examples in the collection of 
the British Museum which I consider to be varieties of this species. They are 
characterised by the presence of only four supero-marginal plates on each side of 
the disk, exclusive of the odd terminal plates, as against six plates in typical 
examples. Beyond this difference in number and the relatively greater length of 
the supero-marginal plates in proportion to their breadth, I can indicate no 
character worthy of being noted which would distinguish the examples in question 
from the typical form of Mitraster Hunteri. The specimens under notice measure 
35 mm. and 30 mm. in diameter (R -{- r) respectively. Both are from the Upper 
Chalk, one from near Bromley, the other being only labelled " Kent." Figures 
of the first-mentioned are given on PL IX, figs. 3 «■ — 3 e. 



MITRASTER RUGATUS. 6» 



2. MiTRASTER RUGATUS, Forbes, sp. PI. XVI, figs. 3 a — 5 d. 

GoNiASTEB (GoNiODiscus) RUGATUS, Forhes, 1848. Memoirs of the Geological 

Survey of Great Britain, vol. ii, 
p. 471. 

— — — Forbes, 1850. In Dixon's Geology and 

Fossils of the Tertiary and Creta- 
ceous Formatious of Sussex, London, 
4to, p. 330, pi. xxi, figs. 2, 2*; 
pi. zxiii, fig. 15. 

— — — Morris, 1854. Catalogue of British Fossils, 

2nd ed., p. 81. 
AsTEOGONiUM EUOATUM, Dujardtn and Hupe, 1862. Hist. Nat. 

Zooph. Echin. (Suites a Buffon), 

p. 399. 
GoNiASTEE (GoNiODiscus) EUOATUS, .FbrJcs, 1878. In Dixon's Geology of Sussex 

(new edition, Jones), p. 364, pi. sxiv, 

figs. 2, 2*; pi. xxvi, fig. 15. 

Body of small size. General form depressed. Abactinal surface flat. Actinal 
surface also flat. Marginal contour pentagonal with almost straight sides. The 
major radius is proportional to the minor radius as 100 : 75. The actual 
measurements in an example from the Upper Chalk of Gravesend, preserved in 
the British Museum, being, major radius, 17*5 mm.,; minor radius, 13'75 mm. 
The rays are not produced beyond the contour of a true pentagon, and the radial 
angles are not rounded. Margin moderately thick, the lateral wall being almost 
vertical in consequence of the rapid bend from the abactinal and actinal surfaces ; 
the bend to the actinal surface is, however, rather more gradual. 

The supero-marginal plates are three in number, counting from the median 
interradial line to the extremity, or six from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. They 
form a broad border to the abactinal area of the disk, of uniform breadth through- 
out, which measures 6 mm. at the median interradial line in an example whose 
diameter (R -|- r) measures about 31 mm. Excepting the ultimate plates, the 
supero-marginal plates are approximately equal in size, the breadth being nearly 
twice the length, the actual measurements in the above-mentioned specimen of 
31 mm. in diameter being, length 3*5 to 3"6 mm., and breadth 6 mm. in the plate 
adjacent to the median interradial line. The corresponding plate in another 
example has a breadth of 5 mm. and length 2'75 ram., and in a third, breadth 
5*5 mm. and length 2'75 to 2-8 mm. In the plate adjacent to the median inter- 



64 FOSSIL ASTEROIDEA. 

radial line the length at the outer and at the adcentral margin is equal, but in the 
second plate the length at the adcentral margin is greater than at the outer 
margin in consequence of a slight extension of the plate to make up for the 
diminution in size of the ultimate plate, the distal lateral margin of the second 
plate appearing to be slightly hollowed out for the reception of the ultimate plate, 
and the corresponding second plates of two adjacent rays consequently touch at 
their adcentral ends. The ultimate plate is triangular or wedge-shaped in form, 
and its breadth is less than that of the other supero-marginal plates, and the 
corresponding plates of the two adjacent sides touch one another thoughout, the 
line of junction falling in the median line of the ray. The ultimate plate is not 
unfrequently a little longer at the outer margin than the other supero-marginal 
plates. 

The abactinal surface of the plates is regularly convex along the line of 
breadth, almost resembling the segment of a cylinder, and no special gibbosity is 
developed. The abactinal area and the lateral area of the plate form a right angle, 
and the uniting curve is short and abrupt. The height of the supero-marginal 
plates, as seen in the margin, is less than their length, the height being 2'25 mm. 
where the length is 2"75 mm. There is no diminution in height as the plates 
approach the extremity of the ray, and no special prominence is noticeable in the 
ultimate plate. The abactinal surface of the plates is ornamented with irregular 
and frequently elongate eminences or ridges, which are usually disposed trans- 
versely or in the direction of the length of the plate. Two or three series may 
be present, as in PI. XVI, fig. 4, or the linear ridges may be bent at a right 
angle, or otherwise curved — a character which is probably the result of several 
eminences being merged together, by which means a peculiar hieroglyphic-like 
marking is produced, which fancifully resembles Chinese writing to a certain 
extent (see PI. XVI, fig. 5 c). This character is emphasised in weathered 
specimens. The ornamentation covers the whole abactinal area of the plate, but 
does not extend upon the lateral wall. Sometimes the form of the eminences is 
more rounded and tuberculiform, as in Mitraster Hunteri; this is distinctly the 
case in one example, and minute punctations are present in the channels which 
intervene, but it is to be noted that the tubercles and pits cover the ^vhole 
abactinal area of the plate, and that there is no gibbosity, with its outer flank 
devoid of tubercles, as in Mitraster Hunteri. There is a very narrow depressed 
border round the entire margin of the plate, from which the regular convexity of 
the plate rapidly rises. The border is very minutely pimctate, and there appears 
to be usually only a single regular lineal series of punctations. The ornamentation 
of the ultimate paired plates is similar to that on the other supero-marginal 
plates, but is more rounded and tubercle-like even in an example in which the 
broad lineal ornamentation occurs on the other plates. 



MITRASTER RLGATUS. 65 

The odd terminal or so-called " ocular " plate must be very small in order to 
fit the space left by two adjacent ultimate supero-marginal plates ; but I am 
unable to describe the plate, as I have only found a trace of it in one instance, and 
have not seen a perfect one preserved in any of the examples of the species I have 
examined. 

The abactinal area of the disk within the boundary of the marginal plates is 
paved with large polygonal plates, whose surface is marked with a very minute, 
closely crowded uniform granulation, upon which small miliary granules were 
previously borne. Traces of these granules are still occasionally present in some 
examples. The abactinal plates in this species are all large in relation to the size 
of the disk, and the primary apical plates are much larger than any of the others. 
The primary apical plates and several of the other plates have a central, small, 
low, irregular eminence, such as might be formed by the merging together and 
partial grinding down of a number of granules. I am unable to explain this 
structure, or to consider it as associated with a pedicellarian apparatus, of which 
I see no trace. It may possibly mark the remains of a tubercle which had 
existed in an early stage of the animal's life, but had disappeared and been 
outgrown at a later stage. 

The madreporiform body, which is very small, is circularly subtriangular in 
shape, and is marked with fine regularly radiating striations. In the example 
under notice two large plates surround two-thirds of the circumference of the 
madreporite. In this specimen the madreporiform body measures IS mm. in 
diameter, and the largest primary plate is 32 mm. in diameter. 

The infero-marginal plates are five in number, counting from the median 
interradial line to the extremity, — that is to say, there are ten for the whole side of 
the disk as against six in the supero-marginal series. The length of the two 
innermost plates on each side of the median interradial line is greater than that of 
the corresponding supero-marginal plates, consequently the second infero-marginal 
plate extends a little way beneath the ultimate supero-marginal plate, and the re- 
maining three infero-marginal plates are all under the ultimate supero-marginal 
plate. In some examples I am inclined to think that probably only four infero- 
marginal plates were present, counting from the median interradial line to the 
extremity, in which case the edge of the second and the remaining two plates were 
under the ultimate supero-marginal plate. 

I have unfortunately not seen any example of this species in which the actinal 
surface of the disk is exposed, I am therefore unable to give the dimensions of the 
infero-marginal plates on the actinal surface, or to describe their ornamentation. 
For the same reason I am prevented from offering any remarks on the adam- 
bulacral and actinal intermediate plates. 

10 



66 FOSSIL ASTEROIDEA. 

Dimensions. — The example figured on PI. XVI, fig. 3 a, has a major radius of 
about 17'5 mm., and the minor radius is about 13"75 mm. The length of the side 
is about 20 mm. The fragmentary type-specimen figured by Forbes, which is 
drawn on PI. XVI, fig. 5 a, was probably about the same size, judged by compu- 
tation of the half-side. 

Localitij and Stratigrcq^hical Position. — One of the type specimens figured by 
Forbes is stated to have been obtained from the Upper Chalk of Wiltshire, but 
the second specimen, which is now preserved in the British Museum, bears no 
record of any locality. Forbes also records the species from Kent and Sussex. 
Authentic examples from the Upper Chalk from Gravesend and " Kent " are 
preserved in the British Museum. 

History. — This species was described by Forbes in his memoir " On the 
Asteriadee found fossil in British Sti'ata " (' Mem. Geol. Surv.,' vol. ii, p. 471, 
184S), and figures of two examples were given in Dixon's ' Geology and Fossils of 
the Tertiary and Cretaceous Formations of Sussex,' London, 1850, pi. xxi, 
figs. 2, 2* ; pi. xxiii, fig. 15. The latter specimen is now preserved in the 
British Museum (register-number " E 2585 "), and is illustrated on PL XVI, 
fig. 5 a, of the present work. I have not been able to find any trace of the other 
example figured by Forbes, which originally formed part of the collection belonging 
to the late Mr. Channing' Pearce. Forbes states that it was found in Wiltshire. 



o 



Remarlcs. — Although at first sight the differences between Mitraster Hunteri 
and Mitraster rugatus appear well marked, I am not perfectly satisfied as to the 
species being altogether independent. When the types alone are examined there 
appears to be no need for any doubt upon this question. But examples occur 
which are exceedingly difficult to determine on account of presenting features 
which seem to break down some character which has been regarded as diagnostic 
of the other species. In illustration of this difficulty I have drawn on PL XVI, 
fig. 3 a, an example which I have ranked under Mitraster rugatus, but which 
presents considerable superficial resemblance to Mitraster Hunteri in the character 
of the ornamentation of the supero-marginal plates. I believe, however, that the 
proportions of the plates, the absence of any abactinal gibbosity, and the exten- 
sion of the tuberculation over the whole abactinal area constitute, inter alia, a 
justification for regarding the example as Mitraster rugatus. 

Turning, on the other hand, to a series of Mitraster Hunteri, considerable 
variation is to be noted in the relative length and breadth of the supero-marginal 
plates, as well as in the amount of gibbosity developed on the abactinal area of 
the plate. In such an example as that figured on PL XV, fig. 3 a, the proportions 



Ipalxontoovaphical Socict\:, 1003. 



A :\r o X o G R A P H 



ON THE 



BRITISH FOSSIL 



ECHINODERMATA 



THE CUETACEOUS FOKMATIONS. 

VOLUME SECOND. 
THE ASTEROIDEA. 



W. K. SPENCER, B.A., F.G.S. 



PART THIRD. 

Paoes 67— StO; Plates XVII— XXVI. 



L X DON: 
PRINTED FOR THE PAL.EONTOGRAPHIC AL SOCIETY. 

1905. 



PRINTED BT ADI.ARD AND SON, LONDON AND DORKING. 



MITRASTEK CUMPACTUS. 07 

of length to breadth are in the case of the interradial supcro-marginal plates as 
5"6 mm. is to o"7 mm. Further, the tuberculation in this specimen may or may 
not extend over the whole of the abactinal area, the variations being on adjacent 
plates, and the abactinal gibbosity is not strongly developed. In the example 
figured on PI. IX, fig. o, the proportions of length to brcatlth in the case of the 
interradial supero-marginal plates are as 4"5 mm. is to 3*6 mm. ; the granulated 
areas more generally stop short of tlie distal edge of the supero-marginal plate and 
the abactinal gibbosity is well pronounced. In view of these considerable variations 
it is difficult to refer these forms to more than one species. 



:5. MiTKASTKK coMPACTUS, Fovhes, sp. PL XVII, fig. 2; PI. XXVI, figs. 3, 3 a, 3 //, 3 c 

GoNiASTER COMPACTUS, Forbes, 1848. Mem. Geol. Surv. Gt. Brit., vol. ii, p. 468. 
— — Forbes, 1850. In Dixou's Geology and Fossils of the Ter- 

tiary and Cretaceous Formations of Sussex, London, 
p. 333, pi. xxii, fig. 3. 

AsTROGONiUM cOMPACTUM, Dujavdiii e( Htipr. 1862. Hist. Nat. Zooph. fiehin. 

(Suites ii Buffon),p. 399. 

GoNiASTER coMPACTiTS, Forbes, 1878. In Dixon's Geology of Sussex (new edition, 

Jones), p. 366, pi. xxii, fig. 3. 

Specific Charnctcrx. — Outline pentagonal, slightly cvcloidal. Eight supero- 
marginal plates on each side of the pentagon. Supei'o-marginal plates form a broad 
margin, and the breadth of each is about four times its length. Base of ultimate 
paired supero-marginal plate tAvice as long as the othei', more proximal, supero- 
marginal plates. Ten corresponding infero-marginalia. 

Matenal. — Only one specimen of this species is known. 'IMiis formed a portion 
of Mr. Willett's collection and is now preserved in the Brighton Museum. It 
apparently escaped the observation of the late Dr. Wright, for the figure on Plate 
XVII is copied from that in Dixon's ' Geology of Sussex.' As this figure is slightly 
inaccui'ate I have had it redrawn and fui-ther details added on Plate XXVT. 

Description. — The dorsal surface of the disc is covered with a number of small, 
subequal, closely-fitting plates. It is consideral)ly sunk in the specimen known. 

The supero-marginal ia bounding the disc form a uniform margin 5'15 mm. 
broad. They are eiglit in niinil)er along each side, exclusive of the odd terminal 
or ocular plates. The six middle plates are about P2 mm. long. Their breadth 
is rather more than four times their length, a feature which distinguislios tlii-ni 

11 



68 FOSSIL ASTEROIDEA. 

from Mitraster Eiuiteri and M. rngatiis. A further distinctive feature is the size 
of the distal paired plate. This plate is triangular. The base of the triangle 
measures 2*7 mm., giving the plate twice the length of the more proximal plates. 
The plate is gibbous at its outer extremity as in M. Hnnteri. All the plates are 
ornamented with a single or double marginal row of small spinelets. The ocular 
is a small conical plate barely visible in abactinal -saew. It fits into notches on 
the lower surface of the distal paired plates, and is, as usual, notched on its 
inferior surface for the purpose of protecting the unpaired terminal tube foot. 

The median infero-marginal plates are rather longer than the corresponding 
members of the superior series. The first two, reckoning from the median inter- 
radial line, are 1-85 mm. long, and 8-5 mm. broad. The third is only 1"8 mm. long 
and not quite as broad. The fourth has approximately the same length l)ut is 
subtriangular in form. The fifth is a small triangular plate. Two infero-marginals 
and a portion of a third are situated underneath the distal paired supero-marginal 
plate. 

The veutro-lateralia visible are small hexagonal plates covered Avith a fine uniform 
granulation. The adambulacralia are small oblong plates. The margin of the disc 
is very abrupt, but the transition from infero-marginalia to the actinal surface is 
more gradual than that of the supero-marginalia to the upper surface. A number 
of small granules are irregularly distributed between tlie plates. 

Eemarlcs. — Unfortunately, the specimen is slightly distorted, so that the pro- 
nouncedly cycloidal appearance in the figure is partially due to the unnatural 
position of the marginal plates, which has brought the inferior series into the dorsal 
view. The supero-marginal plates appear to have been straight and the inferior 
series but slightly cycloidal. This, together with the large comparative size of 
the ultimate paired plate, would bring the species very near to the genus Meto- 
jxister. Forbes remarked upon the fact that it appeared to be intermediate between 
Goniaster {Mdopaster, Sladen) nncains and Guiiiastt'r (Mitraste); Sladen) nigatiis. I 
have therefore considerable doubt as to the validity of the separation of these two 



genera. 



Localitij and Stratignijihical Fosifioi>. — Upper Chalk of Haughton, Sussex. 



rOMPTOXTA ^O^rPTOXT. 69 



Geuns—COUFTO^IA, Gmn. 

Gray, 1840. Annals and Magazine of Natural History, vol. vi, p. 278. 
— 1866. Synopsis of Starfishes in the British Museum. 

Body depressed, with produced tapering rays. Disc covered abactinally and 
actinally mth numerous polygonal plates which possess a uniform gi'anulation. 
Marginal plates numerous. Supero-marginal plates equal in luimber to the infero- 
marginals, and forming a moderately broad border to the disc. Infero-marginal 
plates (as well as all other plate?) devoid of spines. Radialia present throughout 
length of ray. 

This genus apparently differs from Sfellaster only in the absence of spines on 
the infero-marginaUa. It is thus similar to, as well as prior to Ofjmaster (von 
Martem, 1865) and Dorif/onn {Gmij, 186G). 



1. CoMPTOxiA CoMPTOXi, Fovhes, sp. PI. XVII, figs. 3, 3(7, and oh; PI. XVIII, 

figs. 2, 2 a, 2h,2c,2 d. 

Stellaster CO.MPTOXI, Forbes, 1848. Mem. Geol. Surv. Gt. Brit., vol. ii, p. 476. 

— — Forbes, 1850. In Dixon's Geology and Fossils of the 

Tertiary and Cretaceous Formations of Sussex, 
pi. xxii, fig. 8, p. 335. 

— — Lujardin et Hiipi', 1862. Hist. Nat. Zooph. fichin. (Suites 

a Buffon), p. 408. 

— — Forbes, 1878. In Dixon's Geology of Sussex (new edition, 

Jones), pi. xxii, fig. 8, p. 368, 370. 

Specific Characters. — Disc large and interbrachial arcs wide, gi^nng the disc a 
distinctly pentagonal appearance. !Major radius rather more than twice the length 
of the minor radius. Arms elliptical in cross section. Large valvate pedicellarife 
present. 

Material. — Two specimens (the two cotypes) of this species are in existence. 
One (formerly in the Bowerl)ank Collection) displays the actinal aspect (PI. XVI 1. 
fig. 3), and is preserved in the British Mu.seum of Natural History (34311). 
The other (PI. XVIII, fig. 2), which shows the dorsal aspect, is preserved in the 
Northampton Museum. This is the specimen figured in Dixon. 

Description. — The large pentagonal disc is covered dorsally with numerous 



70 FOSSIL ASTEROIDEA. 

small closely-fitting plates. In the radial areas these plates are polygonal and are 
about 1'8 mm. in diameter. In the interradial areas the plates measure only 1 mm. 
in diameter and are rhomboidal. All the plates are covered with a fine uniform 
granulation (PI. XVIII, fig. 2 a). Upon very many of the plates are valvate 
pedicellarifB. Post-mortem changes have produced a sinking in of the plates over 
the interradial areas. Depressions, doubtless due to similar causes, appear in 
recent forms when dried, as also in C. elegans. I have been unable to distinguish 
either the madreporite or the anus. 

The arms are not so much produced as in C. elegans. 

R : r : : 62 mm. : 29 mm. in the specimen at Xorthampton. 
E. : r : : 55*6 mm. : 2.5'8 mm. in the British Museum (Natural History) 
specimen. 
The width of the arms at the sixth supero-marginal (reckoning from the inter- 
radius) is 11 '5 mm. 

The supero-marginalia are oblong in shape. In the interradial areas thej- are of 
fairly constant size, measuring o*2 mm. in breadth and 2 mm. in length. They 
diminish in size distalwards. They are eighteen in number, and often bear one 
or more valvate pedicellarite. The margin is rounded and is about 8 mm. high. 

The infero-marginalia are equal in number and similar in appearance to the 
superior series. 

The actinal interradial areas are large and filled proxinially with a number of 
small rhomboidal plates about 1'2 mm. in average breadth. The more distal 
plates are crowded, smaller, and polygonal in appearance. Traces of a fine 
granulation are visiljle. 

The adambulacrals are a series of small oblong prominent plates. The largest 
are about l"6mm. in length and 1-2 mm. in breadth. Remains of their armature 
are still present. The mouth-angle plates are small and but slightly j^rominent. 
They also bear traces of armature. Valvate pedicellarite are scattered apparently 
irregularly over all these various plates. 

Locality nud Straiigraphical Position. — Upper Greensand of Blackdown. 

Remarks. — Forbes considered this species was equivalent to Asterias Schiiltzii, 
Roemer.^ In this latter species, however, the superomarginalia meet across the 
dorsal surface of the ray, which would disprove Forbes' statement. 

^ Eoemer, ' Versteiaerungen des Norddeutsclien Kreidegebirges,' pi. vi, fig. 21. 



COMPTOXIA ELEGAXS. 



2. CoMFfOJfU ELEGANS, Grai/. I'l. XVII, figs 4 aiul 1-a. 

CoMPTONiA ELEGAN8, Gray, 1840. Aim. A Mil),'. Nat. Hist., vol. vi. 

p. 278. 
Stellaster ELEOAN.S, Forhes, 18-18. Mem. Geol. Surv. Gt. Brit., vol. ii. 

p. 476. 

— — Forbes, 1850. In Dixou's Geology and Fossils of 

the Tertiary and Cretaceous Fornuitit)ns 

of Sussex, London, p. 336, pi. xxii, fig. Jt. 

CoMPTONiA ELEOANS, Morris, 1854. Catalogue of British Fossils, 2nd ed., 

p. 50. 

— — Dujardin et Hitpr, 1862. Hist. Nat. Zooph. 

fichin. (Suites a Buffon), p. 408. 
Stellaster eleoans, Forbes, 1878. In Dixon's Geology of Sussex 

(new edition, Jones), pp. 369, 370, 
pi. xxii, fig, 9. 

Specific Characters. — Disc strongly convex, covered -with small polygonal 
plates. Actinal interradial areas large. Arms well produced, the major radius 
being at least three times as long as the minoi- radius. Tnterl)racliial arcs 
paraboloid. 

Miiterial. — The specimen figured l)y Dixon, at that time in the Bowerbank 
Collection, is now preserved in the British Museum of Natural History (E. 2507). 
Both dorsal and ventral aspects are exposed. Another specimen showing an 
impression of the ventral surface exists in the Oxford University ^Inseum. 

Dixon's specimen, however, can hardly be the type, since Gray (184-0) stated that 
the specimens described by him were in the British Musenm or in the collection 
of the Zoological Society. Forbes (18-48) refers only to specimens in the British 
.Museum and the collection of the Marquess of Northampton. X'^o part of the 
Bowerbank Collection is knoAvn to have come to the British ]\Iuseum before 1805. 
The type specimen therefore mnst be either lost or still unrecognised in tlie 
national collection. Since it was never figured it could never be identifieil with 
certainty. It is therefore advisable to take the specimen E. 2567 as type. 

Description. — The disc is high in the central and radial regions. In the inter- 
radial areas, however, post-mortem changes have cau.sed a collapse of the test 
and the consequent production of deep triangular depressions. Tlie i)lates 
covering the disc arc minute, polygonal, and closely fitting. The centrale is tlie 



72 FOSSIL ASTEROIDEA. 

only plate of the dorsal sui'face wliicli is larger or moi'e conspicuous than the 
remainder ; all are covered with a minute uniform granulation of a quite charac- 
teristic appearance. The anus is almost central in position. It is surrounded 
by a circlet of plates, amongst which is the centrale. The madreporite is, as 
usual, situated in the next (clockwise) interradius, almost halfway between the 
centrale and the margin. It is a triangular plate, the apex of the triangle being 
a markedly acute ano-le. 

The arms are well produced. R : r : : 30 mm. + : 9 mm. Their breadth at the 
base is mm. Radialia, adradialia, and dorso-lateralia extend into the base of the 
arms. The dorso-lateralia soon disappear, but the adradialia persist as far as the 
seventh or eighth supero-marginal plate. AVhen the adradials disappear the radialia 
become larger. They ai^e at this point 1 mm. broad and I'l mm. long and 
therefore appear almost square. 

The supero-marginalia are oblong plates of curiously uniform size in the portions 
of the specimen preserved. They are 1-6 mm. long and from l'2mm. to 1-omm. 
broad. The infero-marginalia are of the same length and are opposite to the 
supero-marginalia. In lateral view the supero-mai*ginalia appear higher than the 
inferior series. Both series are oi'namented with a number of small, fine a:ranules 
which are uniformly distributed over their surfaces. 

The ventral surface is concave. The ventro-lateral plates are rhomboidal in 
the region of the mouth. They become polygonal and crowded as they approach 
the margin. Some of these plates extend into the base of the arms. Around the 
edges of the plates spinelets are visible. The spines of the adambulacral plates are 
still present. Unfortimately, it is not possible to make out their exact distribution. 
The mouth-angle plates are not prominent. 

There is no trace in this species of such valvate pedicellariae as characterise 
G. Comptoiii. 

Bemarls. — Gray compared this species with Civlaster, Agassiz.^ The rather 
vague diagnosis of Ccchi.'^ter given l)y Agassiz renders exact identification impossible. 

Lorality and Sfr(ifi<jy(i2>ltical Position. — Upper Greensaud of Blackdown. Also 
in the Upper Greensand at Folkestone (observed by Forbes). 

' Agassiz, 'Annales des Sciences Naturelles,' 1837. Trauslated in ' Annals and Magazine of 
Natural History,' vol. i, 1833. 



PENTAGOXASTER RORFSTUS. 73 

Cff-HHS—XYMPH ASTER, Sladen, LSHo. (See p. 14.) 

4. NYMPriASTER RADIATfS, n. sp. PI. XXV, figS. 1, 1 ", 1 li- 

Specific Chdracters. — Anns very mucli produced. R : r : : 150 iniii. : 10 mm. 
Supero-marginalia in contact almost the whole length of arm. 

Matoriiil. — Tlie only specimen of this species, formerly in tlie collection of Mr. 
J. Starkie Gardner, is preserved in the British Museum of Xatural History (E. 375). 
The plates have, unfortunately, disappeared from the disc. Practically all that 
remains is the greater portion of one arm. 

Description. — At the liase of the arm the supero-marginalia are oblong. Each 
measures 2-8 mm. in breadth, 2 mm. in length, and 3 mm. in height. Distally 
these plates become almost square. They are ornamented by small granules 
which tend to ruu together transversally to the length of the arm (PI. XXV, 
fig. 1), and articulations for spines and deep depressions for pedicellarife are also 
present. They are about twenty-five in number. The infero-marginalia erjual 
in number and size and oppose the supero-marginalia. Further they are about 
the same height in marginal view. 

The breadth of the arm at the fourth supero-marginal is (3 nnn. 

Sirati(jraphical Position. — Lower Chalk. Locality uncertain. 



^;,,»„s_PEXTAGOXASTER, Linck. (See p. 24.) 

3. Pentagonaster robustus, n. sp. PI. XXI, figs. 2, 2((. 

Specific Characters. — Disc covered with small rounded plates. Margin high. 
Rays short, high and robust. R : r : : 21-5 mm. : 9-'.» mm. The supero-marginal 
plates meet along the median line throughout almost the whole length of the arm, 
and form a broad border to the disc. Interbrachial arcs paraboloid. 

Material. — The only specimen of this species is the one here described, formerly 
in the Mantell collection and now preserved in the British Museum of Xatural 
History (48085). The locality from which it was derived is stated rather 



74 FOSSIL ASTEROIDEA. 

vaguely as Upper Chalk, Sussex. The specimen is somewhat imperfect, consisting 
only of the dorsal view of three arms and a portion of the disc. 

Description . — The disc appears to have been covered on its dorsal surface hy a 
large number of small, rounded, closely-fitting plates. Mostly they are subequal 
in size and have an approximate diameter of 2 mm. An uncertain number of 
even smaller granule-like plates exist scattered between these. 

Both radialia and adradialia extend into the base of the arms, but only as far 
as the third supero-marginal plate, counting from the median interradial line. 
The arms themselves are short and high. The height of the specimen in the 
interradius is 9'2 nnn. Fi'om this point the height gradually diminishes to the 
extremity of the ray, where it is 5 mm. 

The supero-marginalia are about twelve in number. They form a broad 
margin to the disc and rays. Each supero-marginal plate is high, and is very 
couA'ex dorsally. Hence exevy plate is very distinct. The six proximal supero- 
marginals diminish only slightly in size distalward along the ray. The next six, 
however, diminish much more rapidly. The supero-marginal nearest the inter- 
radius has the following measurements: height, 5'75 mm.; breadth, 4'5 mm.; 
length, 3 mm. 

The ocular plate has broken away, and there is no trace of a madreporite. 

The infero-marginalia alternate with the supei'o-marginal series. They are 
not so high and mi;ch squarer in appearance. They decrease in size much more 
rapidly than the upper series (see PI. XXI, fig. 2 n). The infero-marginal plates, 
nearest the interradius, measure 4'5 mm. high and 3"2 mm. in length. Any orna- 
ment that may have existed has disappeared from all parts. 

Localitj/ and SirafigrcqiJiicd Position. — Upper Chalk, Sussex. 



4. Pentagonastee obtusus, Forbes, sp. PL XXII, figs. 1, 1 a, lb, 2, 2 a, 3 a, 3 b, 

o c, 3 cl, 3 e, of, 3 g. 

Oreaster obtusus, Forbes, 1848. Mem. Geol. Surv. Gt. Brit., vol. ii, p. 468. 

— — Forbes, 185u. In Dixon's Geology and Fossils of the Tertiary 

and Ci-etaceous Formations of Sussex, Loudon, j). 330, 
pi. xxi, fig. 12. 

— — Dvjardin et Kupt', 1862. Hist. Nat. Zoojih. Echiu. (Suites a 

Buffou), p. 389. 

— — Forbes, 1878. In Dixon's Geology of Sussex (new edition, 

Jones), pi. xxi, fig. 12, pp. 364, 370. 



PENTAGONASTER OBTUSUS. 75 

Specific Characters. — Disc slightly convex. Majority of the plates covering 
the disc of snbequal size and closely set. R : r : : 25 mm. : 1"2 iinn. Extremities 
of arms obtuse. Interbrachial arcs only slightly rounded, giving the disc a 
distinctly pentagonal appearance. 

Material. — The two extremities of the arms from which Forbes originally 
described the species when in the Dixon collection, are now preserved in the 
British Museum (Natural History). They are not on the same slab of chalk as 
represented by Forbes, but are and probably always have been two independent 
specimens, E. 5038 (PI. XXII, figs. 3 h, c,<l), and E. 5039 (fig. 3 (/). More complete 
specimens have since been added to the collection (40400, PI. XXII, fig. 1 ex 
J. Simmons' Coll., and 35481, PI. XXII, fig. 2, e.v. H. W. Taylor's Coll.). Two 
extremities of arms ai-e also preserved in the Brighton ]\Iuseum. 

Descnption. — Tlio disc is high and distinctly pentagonal. At the edge of the 
disc the dorsal covering plates are crowded and jioh^gonal in appearance. Towards 
the centre they become slightly smaller and rounded. The average diameter of 
these plates is 1"7 mm. 

The madreporite is subcentral in position. It is about the same size as the 
other plates of the disc and is pentagonal in shape (PL XXII, fig. la). 

The arras are stoutly built. A triple row of polygonal plates enters their 
bases. The adradial series soon disappears, leaving the single radial series, which 
appears to persist until it reaches that part of the ray which is obtuse. From this 
point the supero-marginal plates may or may not be adjunct up to the end of the 
ray. Considerable variation appears to exist as to this point in the single 
specimen examined. The arms are distinctly obtuse in their distal half. This has 
given the species its name. 

The supero-marginalia form a rather broad Ijorder to the disc. There 
are nine supero-marginals from the median interradius to the extremity of the 
ray. Towards the end of the ray the plates of this series become narrower, more 
oblong in appearance, and distinctly convex. 

The infero-marginalia are equal in number and situated generally alternating 
with the supero-marginal series. They are distinctly square in shape, especially 
at the obtuse extremities of the ray. Their ornament is in some specimens not 
so coarse as that of the supero-marginals. 

The actinal interradial areas are very distinct and are occupied by four series 
of ventro-lateral plates. As usual, the actinal plates near the mouth are larger and 
more rhomboidal than the distal plates. Ventro-lateral plates only extend 
throughout about a quarter of the length of the arm. 

12 



76 FOSSIL ASTEROIDEA. 

The moutli-angle plates are not pi'ominent. The adambulacral plates possess 
a triple row of spines. 

Dimensions. — Specimens 35,481 and 40,400. — The greatest -width of the ray 
varies from 8'3 to 6*5 mm., and the least width from 7'2 to 5"7 mm. The supero- 
marginal plates are 3'2 mm. broad near the interradii. 

Specimen E. 5038. — Greatest width of ray 10" 5 mm. 

Specimen in Brighton Museum. — Greatest width of ray 9*2 mm. 

Localitj/ and Stratigraphical Position. — Upper Chalk, Lancing, Sussex, and 
also from the Upper Chalk of Kent. 



PaHuV//— PEXTACEROTID^ {Gray) emend. Perrier, 1834. 

Phanerozonate Asteroids with unequally developed marginal plates, the superior 
series being frequently masked or hidden in membrane. Abactinal skeleton 
reticulate. Plates with large isolated tubercles, or spinelets, or granulose, or 
covered with membrane. Actinal interradial areas with large pavement-like 
plates which bear unequal-sized granules. 



GenHs— PEXTACEROS, Schidrw, 17G0. 

Pentaceeos, Schuhe, 17G0. Betrachtung der versteinerten Seesteme imd ihrer 

Tlieile, Warscliau u. Dresden, p. 50. 
GoNiASTER (pars), Agassiz, 1835. Mem. Soc. Sci. Nat. Neuchatel, t. i, p. 191. 
Pentaceeos, Gray, 1840. Ann. and Mag. Nat. Hist., vol. vi, p. 276. 

Oreastee, Mailer and Troschel, 1842. System der Asteriden, p. 44. 

Generic Characters. — Form stellate, marginal plates conspicuous, defining the 
ambitus. Abactinal plates regular, with more or less definite intermediate papular 
areas. Prominent localised mammillated tubercles or spines present. 

All the fossil species of this genus possess intermarginalia, but do not other- 
wise approach Sladens' genus Pentaceropsis which possesses this character. Li 
view of the fact that intermarginalia may occur as a variation in unmistakable 
recent species of Pentacerus this character cannot invalidate the admission to the 
present genus of the species about to be described. 



PENTACEROS BULBIFERUS. 77 



1. Pentacebos BULBIFERUS, Forbcs, sp. PI. XX, figs. 1, 1 (/, 1 h, and 1 *• ; figs. 2, 2 a, 

and 2 i ; PI. XXI, figs. 1, 1 «, 1 h, 3, 3 a, 
4, 4 a ; PI. XXIII, figs. 2, 2 a. 



Oreaster BULBIFERUS, Forhes, 1848. Mem. Geol. Sun'. Gt. Brit., vol. ii, p. 468. 

— — Forhes, 1850. In Dixou's Geology and Fossils of the 

Tertiary and Cretaceous Formations of Sussex, 
pp. 328, 329, pi. xxiv, fig. 7. 

— — DiijanUn et Hiqh', 1862. Hist. Nat. Zooph. Echin. (Suites 

a Buff on), p. 389. 

— — Forbes, 1878. lu Dixon's Geology of Sussex (new 

edition, Jones), pp. 363, 370, pi. xxiv, fig. 7. 

— — P. H. Carpenter, 1882. Geol. Mag., p. 12. 

Specific Characters. — Disc and arms very convex. The centrale and primary 
interradialia large and tuberciiliform. Tlie major radius approximately twice tlie 
minor radius. Radialia of the arm conspicuous. Extremities of the arms swollen. 

Material. — The specimens figured and described are all preserved in the 
British Museum (Natural History). E. 5040 (PI. XXI, fig. 1), 40175 (PI. XX, 
fig. 1), 48748 (PI. XX, fig. 2), and E. 5041 (PI. XXI, fig. 3), which were bought 
from J. Simmons, and 40399 (PI. XXI, fig. 4), from the collection of E. Charlesworth, 
are all labelled as coming from the Upper Chalk of Bromley, Kent, which, 
however, seems to be an inexact dealer's locality', probably intentionally mis- 
leading. E. 5042 (PI. XXIII, fig. 2), also bought of J. Simmons, is labelled 
"Upper Chalk, Charlton, Kent." 

Other specimens are known in the Sedgwick Museum, Cambridge, Northamp- 
ton Museum, and Brighton Museum. Specimens have also been described by 
Valette from the South of France. 

This seems to be much the commonest as well as the most graceful of the 
Chalk Pentacerotidje. 

Description. — The general aspect of the plates of the disc gives this species a 
very characteristic appearance, for the five primaiy interradialia and the centrale 
are very prominent. They have a lobed widely-spreading base, and are swollen 
on the upper surface into an almost spherical form. Their weathered surfaces 
are pitted in a very regular manner, the pits indicating the former presence of 



78 



FOSSIL ASTEROIDEA. 



granules. Sometimes the granules are still present in situ. The pits are 
separated in the example figured PI. XXI, fig. 1, on an average rather less 
than their own diameter apart. There may or may not be a slight margin to the 
plate. The centrale in a specimen R : r : : 40 : 20 measures 8"5 mm. in diameter. 
The primary interradialia are rather smaller, being 67 mm. in diameter. Radially 
the most conspicuous plates of the disc are the proximal radialia. They have a 
very characteristic appearance, their general shape reminding one of a breastplate. 
The remainder of the plates of the disc are of vei'y various sizes and distributed 
in a fairly regular manner. The general arrangement of these plates is given in 
the general account at the conclusion of these volumes. 

The madreporite is a conspicuous plate lying at the distal end of a primary 
interradial. The two neighbouring adradialia are notched for its reception. 

The arms are moderately produced, the major radius being about twice the 
minor radius. Measurements of five specimens give the following : 



B 



40 mm. 


20 mm. 


35 mm. 


17 mm. 


50 mm. 


25 mm. 


50 mm.. 


25 mm. 


50 mm. 


20 mm. 



At the Ijase of each arm there are five series of plates visible on the dorsal 
surface — the radialia, adradialia, and supramarginalia. All the plates at the base 
of the arm overlap. They are of a type which may be derived from the breast- 
plate shape mentioned above. They gradually become narrowed in length and 
increased in breadth until they are shaped somewhat like an inverted T (PI. XX, 
fig. 2 b). The granulation is generally confined to the central region of each plate. 

The arm aboiit halfway along its length becomes swollen and the plates no 
longer overlap but are contiguous. They lose their J.-shaped form, become 
almost oblong, and at the same time rather tumid. This is especially noticeable 
in the case of the radialia. The form of the plates is, however, rarely absolutely 
regular, but one which is generally derivable from the breastplate shape. 

If we examine a ci'oss-section of the arm, we see that the base of the plates 
of the dorsal intermediate series is prolonged inwards (and ventralward), so that 
a single isolated plate appears club-shaped. 

All the plates are pitted for granules except at the extreme margin. 

The supero-marginal plates are from twelve to thirteen in number, the infero- 
marginals from thirteen to fourteen in number. The arm is very high and botli 



I'KXTACEROS lirLBTI-'KRUS. 70 

iufero- and supero-margiiial plates appear in dorsal view. In fact, the infero- 
marginal plates do not take any part in the formation of the actinal surface. This 
is parallelled in niodoru species of Pentacerot^, e.g. P. clarattis. In marginal view 
the supero- and infero-marginals at the extremity of the ray very distinctly 
alternate. This alternation persists at the base of the arms, hut here it is not 
always so obvious. 

The supero-marginals are much higher than the infero-marginals, and also more 
oblong in shape. Both supero- and infero-marginal plates are regularly but 
coarsely pitted for granules. 

In spechnen figured on PI. XX, fig. 1, we obtain the following measurements: 
Breadth of fifth infero-marginal from the extremity of ray . -j'S mm. 
Lenj^th „ „ „ „ „ .4 

Breadth ,, supero-marginal „ ,, „ . 9"2 ,, 

Length „ „ „ „ „ . 3-9 „ 

Breadth „ radialia „ ,, ,, . 5"8 „ 

Length „ „ „ „ „ . 4-4 „ 

Width of ambulacral groove . . . . . 1-2 „ 

The ocular is visible in this specimen. It is about 1"0 mm. in length and 
breadth. The extremity is slightly pointed, and its ventral surface is hollowed out. 
A ventral view is figured on PL XXI, fig. L Ventro-lateral plates extend 
almost to the extremity of the arms. These are, as usual, rather greater in breadth 
than in length. The ailambulacral plates appear to be about half the length of 
the bordering actinal plates. Their armature consists of several rows of spinelets 
arranged in pairs. 

A few intermarginalia are present in the interradii. They, as usual, press the 
supero- and infero-marginalia on to the aljactinal and actinal surfaces of the disc 
respectively. 

LocalUy and Straiigyaphical Position. — Upper Chalk, Bromley, Kent; according 
to Dr. Rowe, probably from the Chislehurst caves near that locality. 

Variations. — Variations occur amongst all the si)ecimens, especially with 
regard to the ornamentation of the plates and the madreporite. The British 
Museum specimens, 48748, which occur together in a slab, are especially note- 
worthy, inasmuch as the lowest situated individual possesses on the disc no plate, 
which is bnlbiforni or raised con.spicuously above the remainder. 



80 FOSSIL ASTEROIDEA. 



2. Pentaceeos Boysii, Forbes, sp. PI. XXII, figs. 4, A a, 4h, 4c; PI. XXIII, 

figs. 1,1 a, lb; PI. XXVI, figs. 2, 2 a, 2 b. 

Oeeaster Botsii, Forhes, 1848. Mem. Geol. Surv. G-t. Brit., vol. ii, p. 468. 

— — Forbes, 1850. In Dixon's Geology and Fossils of the Tertiary 

and Cretaceous Formations of Sussex, p. 328, pi. xxi, 
fig. 6. 

— — Dujardin et Hupi^, 1862. Hist. Nat. Zooph. Echin. (Suites a 

Buffon), p. 389. 

— — Forbes, 1878. lu Dixon's Geology of Sussex (new edition, 

Jones), pp. 362, 370, pi. xxi, fig. 6. 

Si^rcific Characters. — The primary radialia and interradialia are large liemi- 
spheroid pimctate tubercles. R : r ; : 80 mm. : 18 mm. Rajs well produced, steep- 
sided, almost square in section, and tapering gradually to the extremity. Onlj- a 
few of the plates of the disc enter the base of the arm. Supero- and infero- 
marginal plates adjunct, the intermarginalia being represented only by a few 
scattered granules. 

Material. — The type specimen was said by Forbes (1848) to be in the collection 
of the Marquess of Northampton. The specimen figured and described in Dixon's 
* Geology of Sussex ' (see reference) was said by Forbes to have been " discovered 
by Major Boys and formed part of his interesting collection." This statement 
does not preclude the hypothesis tliat the specimen figured was also the type 
specimen. Neither specimen (if there were two) can now be traced. The following- 
description is based chiefly on a specimen in the Sedgwick Museum, Cambridge 
(PL XXVI, fig. 2), which shows the actinal surface of the arms and a portion 
of the disc. It is supplemented by reference to a less nearly perfect specimen 
preserved in the British Museum of Natural Histoiy (J. Simmons' Coll., 4G600), 
which presents views of isolated rays (PI. XXII, fig. 4), and an isolated ray seen 
from the dorsal surface (PI. XXIII, fig. 1) in the same museum (Dixon Coll., 48083). 

Bescription. — The disc is covered with a number of rounded or irregularly- 
shaped plates. A circlet of large tubercles is very distinct and characteristic of the 
species. These tubercles are hemispherical and not so swollen as those of 
P. hiilbifenis. They are smooth, and possess a fine distinct ornament, thus 
distinguishing them from the circlet of P. coronattts. Their diameter is about 
8'5 mm., and they seem to be arranged radially and interradially, making a total 
of ten. The madreporite was figured by Forbes. It is roughly triangular in shape. 



PKXTACKROS BOYSTI. 81 

The arms are well produced. R = 80 mm. and i- zi= 18 mm., the major radius 
being thus about four and a half times the minor radius. Tlioy taper gradually 
to the extremity. The breadth of the I'ay about the fourth supra-marginal ])late 
is irS mm. The height of the ray at the same spot is almost exactly the same. 
Tho ravs are steep-sided, and consequently appear almost square in cross section. 

The supero-marginalia are adjunct throughout almost the whole length of the 
rav, for only one or two single radialia enter the base of the ray. At the base of 
the ray they are flat and slightly rhomboidal. They possess an anterior indenta- 
tion on their inner surface and are about 3"5 mm. in Ijreadtli. They gradually 
diminish in size distally and at the same time become distinctly swollen. They 
numlier al)()ut twenty-ciglit. 

The infero-marginal plates are appioximately of the same size and number as 
the supero-marginals. Both series imbricate slightly. The ornament of these 
plates consists of a number of fine granules in the centre, while there is a distinct 
margin without granulations. 

Between the supero- and infero-marginal plates a few scattered granides repre- 
sent a slight development of the intermarginalia. 

Tlie adambulacrals are a series of small ol)long i)latL's. They border the int'ero- 
marginals from aliout the eleventh supra-marginal onward. They are much worn, 
and but slight traces of their armature I'emain. Al)out five adambulacrals occupy 
the same length as two infero-marginal plates. Proximally there is a single row of 
small plates which separate the two series. 

Only a few scattered ossicles of the actinal surface of tlie disc remain. 

Locality and Stratigraphical Position. — Upper Chalk, Kent. 

BemarliS. — Valette ('Bull. Soc. Yonne,' 1U02) has described a number of 
species of starfishes from the Senonian of the South of France. The remains are 
found as scattered ossicles. Some of these are grouped by Valette as a new 
species which he calls P. senoiiensls. They arc noticed by the author to resemble 
P. Boijsii except that they are smooth and therefore do not have the ornament 
possessed by P. Boijsii. Valette regards this absence of ornament as rendering 
them specifically distinct from P. Boi/sii, as other ossicles found in close 
proximity still possess the ornament. In view of the vagaries of the way in 
which solution may occur, I cannot admit this contention and consider that it 
is much more probable that tlie ossicles at one time possessed ornament and 
were identical ^\^th P. Boijsii. All the other ossicles except those of the so-called 
Arthraster senonensis {fide infra, p. ii2) were identified with English Cretaceous 
genera, which would support this contention. 



82 FOSSIL ASTEROIDEA. 



3. Pentacekos coronatus, Forbes, sp. PI. XIX, figs. 1, 1"; PI. XXIV, figs. 2, 

2 rt, 2 h, 2 c ; PI. XXV, fig. 9. 

Oreastee coEONATrs, Forbes, 1848. Mem. Geol. Surv. Gt. Brit., vol. ii, p. 467. 

— — Forbes, 1850. lu Dixon's Geology and Fossils of the Ter- 

tiary and Cretaceous Formations of Sussex, pp. 327, 
328, pi. xxi, fig. 7 a—d. 

— — Diijardin et Hvpi', 1862. Hist. Nat. Zooph. Eeliin. (Suites 

•I Buffou), p. 389. 

— — Forbes, 1878. In Dixon's Geology of Sussex (new edition, 

Jones), pp. 362, 370, pi. xxi, figs. 7, 7 a-d. 

Specif c Characters. — Disc large, with conspicuous nodular primar}- radialia and 
interradialia. The major radius is about five times the length of the minor radius. 
Sides of arms very steep, so that the arm appears to be square in cross section. 
A triple row of intermarginalia present in the interbrachial areas. 

Material. — The type specimen of this species is preserved in the British Museum 
of Natural History (Dixon's Coll., 35480). Unfortunately, only one arm and a 
portion of the disc are preserved. A further specimen, registered E. 2562, from the 
cabinet of Mrs. Smith, of Tunbridge AVells, is preserved in the same museum, and 
another example is to be seen in the Museum of Practical Geology, Jermyn Street. 

Descri])tion. — The most conspicuous feature of the disc is the circlet of ten 
"large, more or less polygonal nodose pyramidal tubercles."' These are the 
primary radialia and interradialia. The interradial tubercles are rather larger 
than the radial tubercles, the former measuring 9"2 mm., the latter 7"7 mm. in 
diameter. The remainder of the disc is covered by irregularly shaped jjlates. 

The madreporite has been broken away from the disc of the specimen no. 35480. 
It is figured Plate XXV, fig. 9. 

R : r : : 58 mm, : 19 -\- mm. in the type specimen where the single arm is 
broken short. In specimen no. E. 2562 R : r : : 100 mm. : 20 mm. The arms 
are 30 mm. broad at the base. Their surface is flat, and the sides slope away 
at I'ight angles, so that a cross section of the arm is square. 

Both radial and adradial plates are present in the base of the ray. The 
adradials are irregular in shape and soon disappear. The radials are roughly 
oblong in appearance, and exist throughout that portion of the arm preserved. 
They diminish in size, however, distally. 

The supero-marginal plates are indented on their anterior median surface. 
^ Forbes, in Dixon's ' Geology of Sussex,' p. 327. 



rKXTACEROS SQUAMATUS. 83 

They appear to iiubricate slightly at their margins. The breadth of the fourth 
supero-marginal is 7 mm., the length 4 mm., and the height 3*5 mm. The height 
of the ray at this point is 12"2 mm. 

The infero-marginal plates are opposite to the supero-marginals. They are 
approximately about the same size and numl)er. Between the supero- and infero- 
marginal series a triple series of intermarginalia occurs in the interradial areas. 
The inner and larger intermarginals persist throughout the greater part of 
the length of the arm. It is this intercalated series which gives to the arm its 
great proportionate depth. The outer and smaller series disappear at about the 
seventh and ninth infero-marginal plates. 

The ornamentation of the plates appears to have been worn away, although 
upon many of the plates a distinct marginal area may be seen. 

Upon most of the plates there occur small entrenched pedicellaria? which are 
very characteristic of this species of Pentacei-o^. They consist of a small pit from 
which radiate two fine entrenchments (see PL XXIV, fig. 2 a). 

One of the rows of specimen no. E. 2562 is distorted so as to bring the A-entral 
surface into view. This shows that the ventro-lateral plates extend well towards, 
and perhaps all tlie way to, the extremities of the arm. 

LocaUtij and Sfrati'jniiiliii'"! Position. — The locality of the type specimen is 
given as Lower (Jhalk, Washington, Sussex. The specimen registered E. 25G2 is 
from the Lower Chalk, Burhain, Kent, and the specimen in the ^Museum of 
Practical Geology is from the Lower Chalk, Dover. 

R<>i,inrks. — The specimen registered E. 2562 presents only one or two pedi- 
cellarige, which are so characteristic and numerous on the other two specimens. 



4. l^EXTACKUOS SQUAMATfS, Fnibes, sp. PL XXV, figS. 3, 3 (/, 3 h, O C 

Oreaster squamatus, Forbes, 1848. Mem. Geol. Surv. Gt. Brit., vol. ii, y. -168. 
_ _ Forbes, 1850. In Dixon's Geolof,'y im.l Fossils of the 

Tertiary and Cretaceous Formations of Sussex. 

p. 328, pi. xxiii, fig. 7. 
— — Diijardin el Hupr, 1862. Hist. Nat. Zooph. Rchin. (Suites 

.\ Buffou). p. 389. 
_ _ Forbes, 1878. In Dixon's Geology of Sussex (new edition, 

Jones), pp. 363, 370, pi. xxiii, fig. 7. 

Specific Charnders. — Disc higli, with conspicuous i)rinuiry radialia, inter- 

1 :] 



84 FOSSIL ASTEROIDEA. 

radialia and centrale. Major radius about four times the length of the minor 
radius. Only radialia enter the base of the arm. Dorsal surfaces of arms flat, 
sides slope away at an obtuse angle from this. Ossicles distinctly imbricating. 
A few intermarginalia present. 

Material. — The only specimen of this species is preserved in the Brighton 
Museum. The specimen consists of the disc and a portion of three arms. On the 
whole little displacement of the ossicles has taken place. 

Description. — The disc is strongly convex, and is covered with the circlet of 
primary radialia and interradialia which are disposed around the centrale. All 
these ossicles appear shaped like a breast-plate. The centrale has a diameter 
of 4" 2 mm. The primary interradialia are larger, possessing a diameter of 
b'S mm., whilst the primary radialia are the smallest of the series, measuring only 
3'7 mm. across. Between the centrale and the primary interradialia a number 
of irregularly distributed plates appear. In the next right-hand interradius 
to the madreporite a number of these appear to have surrounded an anal opening. 
The primary interradialia almost touch one another, and the radialia consequently 
I'est on the bases of pairs of ossicles. A few adradialia are pi'esent, but they are 
confined to the disc. A pair of them help to enclose the madreporite, which 
is a polygonal plate 9 mm. in greatest diameter. The ornamentation of the 
ossicles is rather coarse when present, but usually it is very much worn away. 

The arms are well produced. R : r : : 30 -|- mm. : 7"8 mm. They are 1'3 mm. 
in breadth at the base. After the fourth or fifth radiale the remainder become 
minute but persist throughout the length of the arm preserved. 

The supero-marginalia are finger-shaped ; they, as also the infero-marginalia, 
distinctly imbricate. The dimensions of the third supero-marginal, reckoning 
from the median interradial line, are as follows : length 2-3 mm., breadth o"l mm. 
The long axes of the supero-marginal plates slope away distally, thus causing 
])airs of plates to assume the shape of arms of a V. They are at least thirteen 
ill number. 

The infero-marginal plates are similar in size antl number to the supero- 
marginal series. In the interradii a few intermarginalia are present. These force 
tlie supero-marginal series to the surface of the disc. 

Xothing is known of the ventral surface. 

Locality and Stratigrapliical Fosition. — Upper Chalk, Woolwicli. 



PEXTACEROS OCELLATrS. 85 



5. Pentaceeos ocellatus, Forbes, sp. I'l. XXV, fii,rs. 4,ia. 

Oreaster ocELLAxrs. Fiirbef, 1848. Mfiii. Geol. Surv. Great Brit., vol. ii, 

p. 468. 

— — Forbes, 1850. lu Dixon's Geology and Fossils of the 

Tertiary and Cretaceous Formations of Sussex, 
p. 329, pi. xxi, fig. 13. 

— — Diijardin et Hiqx', 1862. Hist. Nat. Zoopb. Echiu. 

(Suites a Buffon), p. 389. 

— — Forbes, 1878. In Dixon's Greologv of Sussex (new edition, 

Jones), pp. 364, 370, pi. xxi, fig. 3. 
Pentaceeos — McPherson, W., 1902. Rep. Brighton Nat. Hist. Soc. 

Specific Characters. — Ventro-lateial plates (a.s pi'obably also the dorsal plates) 
depressed and finely striated on tlu'ir truncated surface so as to simulate the 
surface of a madreporite, with sides rugged and ocellato-punctate. Between these 
plates smaller ossicles of a similar cliaracter are interspersed. 

Material. — But one specimen of this species was known to Forbes. This is 
preserved in the British Museum of Xatural History (Dixon Coll., E. 2571). It is 
a mass of ossicles which look as if the}' were derived from the dorsal surface of the 
disc. They are more spheroidal and somewhat lavoci' than the ossicles of the 
ventral surface of the more nearly jjcrfect example discovered by Mr. AVilliam 
McPherson in the Senonian Marsu])ites l)and at Brighton. This he presented 
to the British Museum (Xatural History) in 1901 (E. .jt>12). 

Description. — The disc and arms are unknown. The specimen no. E. 5012 shows 
a well-preserved portion of the ventral surface. The mouth-angles were occupied 
by single initial rhomljoidal ossicles. To these succeed the ventro-lateral ossicles 
which border the am])ulacral groove. These are pentagonal ossicles of very 
uniform size. The length of the exposed sides of the ossicles l^ordering the 
groove is 4'4 nina. and the greatest breadth of an ossicle 4*2 nnn. The remaining 
ventro-lateral plates are hexagonal, but of almost the same dimensions, although 
the plates appear to become a little larger distally. 

The plates overlap one another consideraljly, rendering precise measurement 
difficult. Between the larger plates are interspersed large numbers of smaller 
and more irregular ossicles which fill up the angles between their sides. The 
whole test would l)e thus very strongly built. 

Both larger and smaller plates are curiously similar in appearance. The 



86 FOSSIL ASTEROIDEA. 

luadreporiform striatious on the truncated summits and the ocellato-punctate sides 
give a most characteristic appearance and render the species unmistakably distinct 
from all known species of Peutaceros. 

The ambulacral groove is 3-5 mm. wide. The adambulacrals are difficult of 
recognition and have prolmbly for the most part been lost, but a large number of 
the hour-glass shaped ambulacrals may be seen. 

Localiti/ and Stratigraphical Horizon. — Upper Chalk, Kent; Upper Senonian, 
Brighton. 



6. Pentacebos abbeeviatits, n. sp. PI. XXIV, figs. 1, 1 a, 1 b, 1 c. 

S2)ec{tic Characters. — Body of medium size. Arms moderately produced, but 
their breadth making them appear stumpy, rounded at the extremities, and hemi- 
spherical in cross section. Five series of dorsal ossicles enter their base. Of these 
the radialia and adradialia persist throughout the length of the arm. A few small 
intermarginalia are present. 

Material. — There is only one specimen known of this species, and of this 
practically all that remains are two arms. It is preserved in the British Museum 
of Natural History (J. Tennant's Coll., 57538). 

Description. — These arms are characteristically wide, the width of the arm at 
the base being 31 mm. They narrow very gradually towards the extremity. 
Throughout the ray the ossicles, except for the differences noted below, are very 
similar in appearance. At the base of the ray, where dorso-lateralia also enter into 
tlie composition of the dorsal skeleton, they are rounded and possess interspaces 
of considerable extent. These interspaces are often filled by smaller granules 
arranged irregularly. At times, however, between two radialia or adradialia one 
of the smaller ossicles is arranged in a very regular and alternating manner. Both 
large and small ossicles are finely granulated, and the large ossicles alone are 
])erforated for pedicellarife. The average size of the larger ossicles at the base of 
tlie arms is about G mm. Towards the extremity of the ray the radialia, adradialia, 
and marginalia become hexagonal, and fit very closely so as to make a compact 
skeleton. The terminal ocular plate is hexagonal and conspicuous. It has a 
flattened articulation which undoubtedly was originally occupied by a spine. 
Several of the other dorsal plates in the distal portion of the ray also possess 
.similar articiilation. 



PEXTACEROS BISPIXOSUS. 87 

The snpero-inarginalia and infero-iuarginalia are ecjual in innnber. Tliere 
were probably thirteen of each in the space between an interradius and an 
extremity of an arm. 

In the interbrachial arc there is a series of minnte granuhvr intermarginalia. 

The traces of the disc which are present suggest that the ossicles of this region 
were oval in shape and minute in size. I exposed a portion of the ventral surface 
of the arm, but, unfortunately, little trace of structin-e was shown. The vontro- 
lateralia extended to the extremity of the ray. The ridges of the adambulacral 
armature are lost. 

Localitij ami StriitiijrapJtical Position. — Upper (^'halk, Charlton, Kent. 



7. Pentaceros bispixosus, n. sp. PI. XXIII, figs, o, o ", o b, 3 c 

Specific Ghamctcrs. — Disc large. Arms moderately produced. Single isolated 
marginal ossicles vertebra-shaped with biconcave extremities. Ventro-lateral 
plates with strongly marked sockets for two or more spines. 

Material.— Hhe only specimen of this species is that jDreserved in the British 
Museum of Xatural History (H. ^Y. Taylor's Coll., 35482). Only the ventral 
surface is exposed, and this is very much distorted. 

Description. — The disc appears to have been large. Its actinal surface is 
covered with a number of sub-equal oblong or polygonal plates, which possessed 
sockets in which fitted spines (PI. XXIII, fig. 3c). These plates are 4-8 mm. 
long, and 3'1 mm. wide. 

The arms are moderately broad, and at least four series of voutro-lateral plates 
enter at the base. R : r : : CO mm. : 20 mm. (approximately), the major radius 
therefore measuring about three times the minor radius. The marginal ossicles 
are shaped very much like the centrum of a vertebra, anil are biconcave. They 
possess a distinct granulation in their central region, which is surrounded by a 
wide margin. The infero-marginals at the base of the ray are about 3'2 mm. wide 
and 2'1 mm. long. There were probably sixteen of them from the interradius to 
the extremity of the ray. 

The specimen is otherwise so distorted that little can Ijo made of its structure. 

Locality and Stratiijraphical Position. — Upper Chalk, Sittingbourne, Kent. 



88 FOSSIL ASTEROIDEA. 

The following are placed provisionally in the genus Pentaceros : 

8. Pentaceros punctatus, n. sp. PI. XXVI, figs. 1, 1 a, 1 h. 

Specific Characters. — Body of large size. Marginal series of plates possessing 
well-developed foraminate pedicellarise. Intermarginalia present. 

Material. — The only example of this species is a fragmentary portion of an 
arm preserved in the British Museum (Natural History) and bearing tlie 
registered numlier E. 2561. 

Description. — The body of tlae starfish must have been of large size. The 
supero-marginals are in contact in the extremity of the arm, although interspersed 
granular plates occur. Proximally, at least, radial plates were present. The 
largest supero-marginal present is 11"2 mm. high and 6'5 nun. long in its widest 
point. It is of rather irregular shape and possesses two foraminate pedicellarije. 
The infero-marginal plates alternate with the supero-marginals. They are of the 
same height as the supero-marginals but only 5 mm. broad. They are oblong in 
shape ; the two interior corners of the oblong, however, are cut away, making the 
ossicles six-sided. The foi'amina once occupied liy the pedicellarite are deep and 
often situated in a depression. From the foramen itself ridges may run out, 
which probably served for the attachment of muscles. 

The infero-marginal series border only the side of the arm and take but little 
part in the formation of the ventral surface. 

An intermarginal series of rounded granular plates occurs. 

Locality and Stratigraphical Position. — Upper Chalk. 



9. Pentaceros pistilliferus, Forhes sp. PI. XXY, fig. 5. 

Obeasteb pistilliferus, Forhes, 1848. Mem. G-eol. Surv. Great Brit., vol. ii, p. 467. 
— — Forbes, 1850. In Dixon's Greology and Fossils of the 

Tertiary and Cretaceous Formations of Sussex, 
p. 329, pi. xxi, fig. 1.5. 

— piSTiLLiFOEMis, Dujardiii et Htipr, 1862. Hist. Nat. Zooph. Echin. (Suites 

a Buffon), p. 389. 

— PISTILLIFERUS. Forhcs, 1878. In Dixou's Geology of Sussex (iiew edition, 

Jones), pp. 363, 370, pi. xxi, fig. 15. 



PEXTACEROS. 89 

Specific Characters. — Primary radialia (or interradialia) large with a dilated 
summit which possesses no ornament and is excavated into pits. " Ossicles of the 
arm are narrow, slmttle-shaped, tumid m tlie centre and slightly impressed 
towards each extremity " (Forljes). 

Material. — Several fragmentary remains of this species are known. The most 
nearly perfect remains are those in the Museum of Practical Geology, Jermyn 
Street. Other specimens are in the British Museum (Natural History), registered 
E. 5037, 57624, E. 2564 (all PI. XXV, fig. 5), 7600, E. 25637, E. 2565. 

Description. — X^othing is known further than the description given in the 
diagnosis. Forbes' description reads as if he had described the species from the 
specimen in the Museum of Practical Geology. This originally was in the collec- 
tion of the Marquis of Xorthampton. Forbes seems to have described the large 
ossicles upside down. He also says they were in a circlet of five, which is not 
apparent in any specimen known. The roughened and pitted surface recalls in 
some respects the jn-iniarv I'adialia and interradialia of P. coronatus. 

Ldcalitij and Striitiijrdjiliiral I'usiticn. — Upper Chalk, Kent and Sussex. 



in. Pextaceros, sp. PI. XXV, fig. 7. 

This specimen is preserved in the British Museum of Xatural History (no. 5514). 

It consists of five marginal plates which are 12"3 mm. high, and have an 
average length of 5*5 mm. The plates are rugged in appearance and the orna- 
ment is worn away. A cirral of a crinoid (probably Boiirgttetiocrinus) has become 
fixed between two of these plates. 



1 1. Pentacekos, sp. PI. XXV, fig. 8. 

The only specimen is presei-ved in the Brighton Museum. It consists of a few 
marginal plates. The supero-marginals are rather irregular in shape, some being 
almost wedge-shaped. On an average they are I iniii. high and 3'2 mm. long. 
The infero-marginals are opposite and equal in length to the supero-mai-ginals. 
They are only 2-it iniii. high. The plates possess a distinct margin, but the 



90 FOSSIL ASTEROIDEA. 

ornament otherwise is worn away. There are a few small granular inter- 
marginalia. 

With these plates is associated a large plate which appears to be a worn radial 
or interradial of P. Botim. 



7<\,„j//^_ASTR0PECTINID^ {Gray, 1840), emend. Sladen, 1886. 

Phanerozonate Asteroids with large marginal plates bearing spines or spiniform 
papilla?. Abaetinal skeleton with true columnar papillpe. Actinal interradial areas 
small, interradial plates when present spinose. Ambulacral plates short and more 
or less compressed. Superambulacral plates present. Aproctuchous. Pedicellarite 
rarely present. 



^e?ws— ASTROPECTEN, G. F. Sclmhe, 17C0. 

Adambulacral plates touching the infero-marginal plates along the ray. 
Marginal and adambulacral plate not correspondent in length and number. Supero- 
marginal plates more or less well developed. Marginal plates long and more or 
less quadrate. Superior and inferior series subequal. 



ASTIIOI'ECTEN, Sp. PI. XXV, figS. 2, 2 11. 

Material. — There is one specimen in the Sedgwick Museum at Cambridge, which 
looks like an Asiru])ecten. It is figured on PI. XXV, figs. 2 and 2 (/. Practically 
oidy the marginal plates are preserved. 

Di'srripfinii. — R : r : : 4-5 mm. : 1-5 mm. The interbrachial arcs are well rounded. 
The supero-marginalia are remarkably uniform in size throughovit the greater 
portion of the ray. Their breadth is 4 mm. and length l"? nun. About thirty of 
these are present from the interradius to the extremity. At the apex of the ray 
these plates are adjunct. The upper surface of each plate is rounded. 

The infero-marginalia are equal in size, opposite to, and, as far as one can 
judge, similar in appearance to, the superior series. There is a distinct groove 
between the two series. 

LociiUtii (111(1 Sfr(ifi(/>'(iji}iic((l J'osifidK. — Upper Grcensand, Rlackdown (?). 



ipaUxontoovapbical Soctct\>, 1007. 



A MONOGRAPH 



ON THE 



BRITISH FOSSIL 



ECHINODERMATA 



FEOM 



THE CRETACEOUS FORMATIONS. 



VOLUME SECOND. 
THE ASTEROIDEA AND OPHIUEOIDEA. 

BY 

W. K. SPENCER, B.A., F.G.S. 



PART FOURTH. 
Pages 91—132; Plates XXVII— XXIX. 



LONDON: 

PRINTED FOR THE PALiEONTOORArUICAL SOCIETY. 

1907. 



PRINTED BY ADLARD AND SON, LONDON AND DORKING. 



ARTHRASTER DIXONI. 91 

FAMILY UNCERTAIN. 
^^„„s_ARTHR ASTER, Forbes, 1848. 

Arms stout ami long. Radialia, marginalia, and vcnti'o-latrralia form an alter- 
nating series of seven very completely articulating similar ossicles, wliirli tit so 
closely as to leave no conspicuous interstices. Each ossicle consists of an oblong 
and flattened base witli a surmounting ridge. Ventro-lateral plates on actinal 
surface of disc small and mammiform. Ossicles on abactinal surface of di.sc 
hemispheroid with a cronulated edge. All the ossicles possess, as ornament, 
hemispherical granular prominences. 



1. AuTHRASTER DixoNi, Forles. PI. XVIII, figs. 1 and la; V\. XXIX, figs. 11 

and 11 a. 

Arthraster Dixoni, Forbes, 1848. Mem. Geol. Surv. Gt. Brit., vol. ii, p. 467. 

— — Forbes, 1850. lu Dixou's Geology of Sussex, p. 336, 

pi. xxiii, fig. 1. 

— — Diijardin el Huj)'', 1862. Hist. Nat. Zooph. ficliin. (Suites a 

Buffon), p. 437. 

— — Forbes, 1878. lu Dixou's Geology of Sussex (new od., Jones), 

pp. 369 and 370, pi. xxiii, fig. 1. 

Specific Characters. — Dorsal ridge of all of the arm ossicles well rounded. 
No spines present except on the adambulacral plates. 

Material. — The best example of this very peculiar starfish is preserved in the 
British Museum of Natural History, Dixon Coll., 47000. The specimen consists 
of the remains of four arms, only one of which is at all well ])rcserved. 
It is the type described Ijy Forbes, and is figured in tiiis Monograph on 
PI. XVIII. A well-preserved fragment of an arm is also in the possession of 
Dr. Rowe, of Margate. I have referred two fragmentary specimens presented to 
the British Museum (E 5023 and E 5024) by Mr. W. McPherson, F.G.S., to this 
species {vide infra). 

Description. — A section of the aim is similar at all points. It shows seven 
ossicles, namely, a radial, the pairs of supero- and infero-raarginalia, and a pair of 
ventro-lateralia. These ossicles all alternate in series, and they closely fit the 
corresponding neighbouring plates in their respective series. The edges of the 
plates possess articulations which as.si^t in forming this close union. All the ])latcs 

14 



92 FOSSIL ASTEROIDEA. 

are generally similar in appearance. They differ, however, in measurements as 
detailed below. 

Breadth of radialia . . . .8-2 mm. 

Length „ „ . . . . 3"5 „ 

Breadth of supero-marginalia . . . 6"2 „ 

Length „ „ ... 3-5 „ 

Breadth of infero-marginalia . . .5-9 „ 

Length „ „ . • . 3-5 „ 

Breadth of ventro-lateralia . . . 4*5 „ 

Length „ ,, ... o'o ,, 

It will thus be seen that the breadth of the plates diminishes as we proceed 
ventralwards. The ridges, also, on the plates, become more rounded in the same 
direction. 

The ornament of the plates consists of hemispherical granular prominences 
of moderate size. They appear to have been especially prominent at the base 
of the ridge. No spine-pits are present. 

The height of the ray is 16'5 mm., and the breadth is about the same. Post- 
mortem conti-action has brought the ventro-lateralia of opposite sides into close 
approximation, in some cases totally obliterating the ambulacra! groove. Along 
one or two of the arms some of the adambulacrals are still visible. They are 
1-8 mm. broad and 1-2 mm. long. The portion of the plate nearest the ambulacral 
groove is depressed, giving the plate a two-storied appearance. 

A few robust, rhomboidal, smallish ventro-lateralia are present at the base of 
the arm. Their breadth is 1-8 mm. They are mammiform. A few similar 
plates also enter the base of the arm. 

The two collections of isolated ossicles presented by Mr. McPherson referred 
to above are very interesting. Each specimen consists of a single ossicle 
simulating one of the abactinal bulbiform ossicles of Peiitaceros, but possessing 
the distinct Arthraster ornament, associated with plates which exactly match the 
ventro-lateralia of A. Dixonl and other plates which resemble the arm plates 
of this species except that the surmounting ridge is not so high. There is no 
doubt that the plates are those of a species of Arthraster. I have little hesitation, 
in spite of their occurrence in the Upper Chalk, in referring the ossicles to A. 
Dixoni, especially as it is a matter of common experience that species of Chalk 
starfish have a wide stratigraphical range. 

Localittj and StratlgrajjMcal Position. — Forbes' type is from the Lower Chalk, 
Balcombe, Sussex. The specimen in the possession of Dr. Rowe was collected in 
the zone of Tcrehratnlina gracilis in Devon. The specimens presented to the 
British Museum by IMr. McPherson are from the Marsiipites zone, Brighton. 



ARTITRASTER CRI8TATUS. 93 

Remarlts. — Forbes coniparetl the genus Arthrastvr with the iiiodorn genus 
Ophiilmster. The hu'ger amount of material known since that time does not allow 
us to recognise such aniuity. 

Valette (see above, p. 81) has described certain isolated plates, which are 
similar in form and size, as belonging to the genus A rtJi raster, and has called 
the species .1. spiinnniKti^. These jilates are smooth and show no trace of the 
surmounting longitudinal ridge or oi'nament which is so characteristic of Arilirastcr. 
Dom Aurelien Valette kindly lent these plates to Dr. Bather in order that I might 
examine them. T am therefore enabled to state that the plates arc those of 
Pyciuaster augustatus. 



2. Artukastki; riasr.vTLs, n. sp. I'l. XXIX, figs. 10, 10(^ 10 b. 

Specific Characters. — Ridges of the radialia and supero-marginalia cristate. 
Upper surface of the ridge of all arm-ossicles possessing lipped pits formerly 
occupied by small spines. 

Matenal. — The specimen figured on PI. XXIX was restored l)y Dr. Blackmore, 
of Salisbury, from a nuiiil)er of isolated ossicles in his collection which were found 
in a single mass of chalk. These ossicles are tlic only material known of the species. 

Description. — Tlie dimensions of the ossicles are as follow : 

Breadth of radialia . . . o'l mm. 

Length „ „ . . . 3-2 „ 

Breadth of supero-marginalia . . -i'8 ,, 

Length ,, ,, . . 3-2 „ 

Breadth of infero-marginalia . •4'2 ,, 

Length „ ,, • • 3-2 „ 

Breadth of ventro-lateralia . . 3"8 „ 



Length 



o 



o 



Just as in A. Divoiii the breadth of the plates diminishes ventralwards, and the 
ridges on the plates become more rounded in the same direction. The cristate 
ridges of the more dorsal plates are, however, very characteristic of the species, as 
are also the lipped pits on the summit of the ridges. The pits were formerly 
occupied by small spines. The base of the ridges of the plates possesses the 
granular hemispherical prominences, such as are also met with in A. Dixoni and 
characterise the erenus. 



o* 



JmciiIUij and ,Strati(jraphical I'onUiun. — Micheldevei-, Hunts. Zone of MicraKter 
cur-anguiaum. 



94 FOSSIL ASTEROIDEA. 



ADDENDUM (to rhancrozonate Asteroids). 

Further investigation, as a result of the privilege of investigating the fine 
collection of Chalk Asteroids in the possession of Dr. Blackmore, of Salisbury, has 
enabled me to describe several new species belonging to genera which have been 
dealt with in previous pages. Some of these species had been recognised but not 
described by Dr. Blackmore, to whom I am indebted for very many valuable 
suggestions. 



F^hh////— PENTAGONASTERID^, Pevrlev, 1884. (See p. 3.) 
Gt'uifs— NYMPHASTER, Sladen, 1885. (See p. 14.) 

5. Nymphaster rugosus, n. sp. PL XXIX, figs. 7, 7 a. 

Specific Characters. — All marginalia covered with granular prominences, which 
are closely crowded, and in no case arranged in a linear series. No spine-pits on 
the marginalia. Margin of disc lunate. 

Material. — Two specimens are known of this species. They are preserved in 
the British Museum (Nat. Hist.), and bear the registered niimbers 5751G (pur- 
chased of AV. Griffiths) and 7G002 (Capron Coll.). Both specimens are imperfect. 
The first-named specimen is figured PL XXIX, fig. 7, and is taken as the type. 

Description. — The two specimens show the disc to have been small. The minor 
radius in the specimen 5751G measures about 11 mm. The arms are broken off 
short in both specimens, and therefore it is not possible to give the major radius. 

There are about eight infero-marginalia in each interbrachial arc. These are 
all approximately equal in size, being 2*7 mm. long and 1*8 mm. broad. In shape 
they are oblong. 

The margin of the disc is lunate. It is this character and the character of the 
granular prominences which distinguish the species from N. raJiatus. 

LocaUf[/ and Stratigraphical Position. — Lower Chalk, Dover and Folkestone. 



PYCINASTER SENONENSIS. 1»5 

GcHHs— PYCINASTER,' nom. nov. 

Pycnaster, Shxden, 1891 (see p. 21), uou Pomel, 1883. Classif. me'thoJ. Ecliiu., p. 42. 

1. Pycinastkr angustatus, Shulen sp. (see p. 21). PI. IX, figs. 1 '/, 1 1> ; PI. XXI, 

figs. 2, 2a ; PI. XXV, fig. 7 ; 
PI. XXVI, figs. 4, 4 a, 4 b. 

This species appears to be quite common in the Upper ('lialk. An exceedingly 
well-preserved specimen is in the collection of Dr. Blackmore, of Salisbury. 

The following specimens, which belong to the genus Piiriwistev, and probably to 
tliis species, have been erroneously ascribed by me to other genera and si)ecies in 
Part III of this volume (pp. 67-90). 

The single specimen described on p. 73 as a new species, Pentagonastev rohustns, 
is probably an innnature form of this species. A collection of five ossicles described 
(p. 89) as Pcntaceros, sp., and the specimen figured on I'l. XXVI as Calliderma 
mosaicnm, also belong to the species. The latter specimen should be described as 
from the Upper f'halk. 

Dom Aurelien Valette has courteously enabled nie to examine the syn-types of 
his Arthmxtpr senonensis (' Bull. Soc. Sci. Yonne,' 1902, p. 20). They prove to be 
marginals of Pijrin<i^f<-r (ingustatus. Four ossicles referred by him to \\\?,Pentaceros 
senonensis (vide infra) also belong to the present species. 



2. PVCIXASTER SENOXEX.SIS, Wdcttc, sp. PI. XXVI, fig.s. 1, \(i, ll>; PI. XXIX, 

figs. 6, 6 (J. 

Pentaceros senonensis, Valette, 1902. Bull. Soc. Sci. Yonue, vol. hi, pp. 17, 18, 

figs. 1, 2 (uou 3—7). 
— puNCTATUs, Spencer, 1905. Anfea, p. 88. 

Dr. Biackmore's material enables me delinitely to ascribe this species to 
Pyciiiastcr, and to add the following new diagnosis and details : 

Specific Chardcti'rs. — Body of large size. Breadth of marginaUa more than 
twice their thickness. All marginalia smooth or with very shallow hexagonal 
spine-pits. 

Description. — The marginaUa may l)e as much as 20 mm. high. They api)ear 

to be distinguished from the marginalia of P. anijnHtahts, not only by their 

1 lIvKifiit, compact, Homeric form of iri//ciiii. Dom Auri'lien Valette kiudly poiuted out the 
prior use of Pyciiaster to Dr. F. A. liathcr, who suggests the above emeudatiou. 



96 FOSSIL ASTEROIDEA. 

magnitude, but also by tlie manner in wliicli the upper surface is turned over so as 
to make the ossicle P-shaped (compare Text-fig. 23, p. 119). 

Associated with these marginalia are found rounded, smooth ossicles, which are 
correspondingly large, being as much as 12 mm. in diameter, and Avhich are 
undoubtedly ossicles from the abactinal surface of the disc. Their size and form 
(see PI. XXIX, fig. 6) render them liable to be mistaken for ossicles of Stanrander- 
aster (see p. 125). They do not, however, possess spine-pits, and species of Stavr- 
anderaster which do not possess spine-pits are very distinct, having nodular abactinal 
ossicles of a very characteristic appearance (compare S. coronntiis, PL XXIV, fig. 2). 
There appears therefore to be no douljt that these ossicles should be referred to 
the genus Pi/cinader, and probably to P. pundatus. The base of the abactinal 
ossicles of P. augnstatiis is produced, as also in P. crassiis (PL XXIX, fig. 4rt), and 
quite different from the flattened base of these ossicles. 

Itemarlis. — It might be urged that the differences which separate these ossicles 
from those ascribed to P. (ingustatus, are not sufiicient Avarrant for a new sj^ecies. 
I regard the differences, however, given above as important, and though several 
well-preserved specimens of P. augustattis are known, none approaches the large 
size which P. pnnctatua nuist have attained. On p. 81, Pentaceros senonensin, 
Valette, was regarded as probably identical with P. Boi/sii. Examination of the 
original specimens, which I owe to the courtesy of Dom Aurelien, shows that they 
belong to four different species : Staurandemster coronalas, 8. argtts, Pi/ciii aster 
angustatns, and my " Pentaceros ])nnctatns.'' The last species is represented by 
two dorsal ossicles from Les Clerimois (figs. 1 and 2). With the concurrence of 
Dom Aurelien, I therefore take the original of his fig. 1 as type. 

Locality and Stratigra'phical Position. — The specimens in the possession of 
Dr. Blackmore are from Bast Harnham, Wilts., zone of Actinocamax quadratns. 

3. Pi'ciNASTEE CRASSus, n. sp. PI. XXIX, figs. 1, 2, 2 a, o, 3 a, 4, 4 a, 5. 

Specific Cltaractcrs. — Body of large size. Height of marginalia not twice their 
thickness. Median marginalia smooth. More distal marginalia with prominent 
mammilations. 

Material. — There are about eight fragmentary specimens of this species in the 
British Museum (Nat. Hist.). The specimen registered E. 257G (Mantell Coll.) 
shows considerable portions of the actinal surface, and that registered 35498 
(Taylor Coll.) the dorsal view of a well-jireserved portion of one arm. Both these 
arc figured on PL XXIX. Another specimen, registered E. 2028 (Mantell Coll.), 
shows a portion of the abactinal siu'face of the disc. The other specimens are 



METOPASTER QUADRATUS. Wl 

mostly collections of isolated plates. The specimen i-egistercd 35198 is taken as 
the type. 

Descvipflou. — The aljactinal siul'ace of the disc appears to have been covered 
with a nnmber of plates of generally nniform size, with an average diameter of 
about 3*8 mm. A few plates exceed this size, but in no case are they as large as 
the corresponding plates in P. pimctatiis. 

No specimen is sufficiently well preserved to give the proportionate lengths of 
the major and minor radii, but there is no doubt that the arms were considerably 
produced. A row of hexagonal tabulate radialia are present throughout the greater 
portion of the arm. The breadth of the arm at the base in the specimen registered 
E. 2576 is about 22 mm. This specimen, however, judging hy the dimensions of 
the marginal plates, does not by any means appear to have attained the usual size 
of the species. The length of its minor radius is 185 mm. 

The median supero-marginalia are quite smooth and are distinguished from 
those of all other species of the genus by their thickness (Text-fig. 24 <i). 
In full-grown specimens they appear to be 18 mm. in breadth, (i mm. in length, 
and 10 mm. in thickness. More distally the supero-marginalia acquire large 
mamrailate rugosities. 

The infero-marginalia are similar in character to the superior series. 

Two rows of ventro-lateralia enter the base of the arm. Most of the ventro- 
lateralia appear to have been rhomboidal in shape and of uniform size. They 
possess very shallow hexagonal fittings indicating the former possession of 
granules. 

Locality and Stratigraphical Position. — Upper Chalk, Kent. 



Ge«MS— METOPASTER, Shnh'n. (See p. 30.) 

9. Mktopastkr quadratcs, n. sji. Text-figs. 1, 2, p. 98. 

Specific Characters. — Marginal plates in iiiterbrachial ai-eas almost square. 
Raised area on marginal ])lates without spine-pits. Supero-marginal plates rugose 
on interior surface. Ultimate sujiero-marginal plates may or may not be the 
largest of the scries, variation in this respect being especially marked. Abactinal 
plates of disc with distinct stellate marking. 

Material. — There are three fairly perfect and four fragmentary specimens of 
this species in the collection of Dr. Blackmore, of Salisbury. Two of these are 
figured in Text-figs. 1, 2. The species was discovered by Dr. Blackmore, who 
suggested the specific name " qnadratm " on account of the characteristic shape 



98 



FOSSIL ASTEROIDEA. 



of tlie majority of the marginal plates. The type is the specimen figured in Text- 
fig. 2. 

Description. — The abactinal area of the disc is covered with hexagonal plates, 
Avhich have a distinctly stellate appearance on their upper surface. 

The arms are distinctly produced. In the specimen figured in Text-fig. 1, 
R : r : : 41 mm. : 28 mm. In the specimen figured in Text-fig. 2, R : r : : 41 mm. : 



Text-fig. 1. 



Text-fig. 2. 




Text-fig. 1. — a, Abactinal view of a sijecimen of M. quadraius,na.t. size; h, actinal view of the 

same specimen : c, view of infero-marginal plate magnified two diameters ; d, view of two 

supero-marginal plates magnified two diameters. 
Text-pig. 2. — a, Abactinal view of another specimen of M. quadraUis, nat. size; h, actinal view of 

the same specimen ; c, view of infero-marginal plate magnified two diameters ; d, view of two 

supero-marginal plates magnified two diameters. 

30 mm. The length of the side in the first-named specimen is 51 mm., in the 
second-named specimen 5G mm. 

The supero-marginalia ai'e either five or six in number, counting from the 
median inter-radial line to the extremity of the arm. In the inter-brachial area 
they are distinctly quadrate in charactei', and are from 7 to 8 mm. in width and 
from G to 7 mm. long. 

The terminal paired supero-marginalia present very curious features. In 
the specimen figured in Text-fig. 1 some of these plates are large and tri- 



STAURANDER ASTER ARGUS. 0'.> 

angular, just as in a typical Metopaster. Otlier terminal plates are, however, 
small and approximate to those characteristic generally of Anieroiih-a. The 
specimen figured in Text-fig. 2 presents no terminal plate which lias a re.seml)lance 
to those typical of Mctopaster. In all other respects the specimens are almost 
exactly similar to one another. 

The infero-marginalia are smooth and sliglitly concave in tlie centre. They 
are eight in number. 

The actinal area of the disc is covered with sub-equal plates, which are four- 
sided in the inter-radial regions and tend to become hexagonal radially. 

Locality and Sfratlgraphical Position. — Zone of Aclinocama^c qaadratas. East 
Harnham, Salisbury. 

Remarls. — The ornament of this species is identical with that of M. uncaius. 
The important differences between the species lie in the shape of the marginal 
plates, the character of the terminal supero-marginalia which show their es))ecial 
peculiarities in all the specimens, and the ornament of the abactinal plates of 
the disc. 



Fawi/y— PENTACEROTID^ {Grai/), emend. Perrier, 1884. (See p. 7G.) 

Gfemt.s— STAURANDERASTER, novum. (See p. 125.) 
12. S. AKGUS, n. sp. PI. XXV, figs. 6, 6 r^ ; PI. XXIX, figs. 8, 8a, l», 9 a. 

Specific Characters. — Ossicles ocellato-])unctate. Surface of ossicles very 
rarely truncate. If truncate, the flattened surface is not striated so as to simulate 
the asteroid madreporite. 

Material. — Only very fragmentary specimens of this species are known. The 
best preserved specimen is in the collection of Dr. Blackniore, of Salisbury, anil is 
figured on PI. XXIX. Dr. Blackmore also possesses other specimens belonging 
to this species. Two specimens of the species are also preserved in the IJi'itish 
Museum (Nat. Hist.), and bear the registered numbers E. 501*.> and E. 25GG 
respectively. The first-named specimen was presented by 'Mr. W . .Mcl'lierson. 
The second specimen was originally figured by Forbes in Dixon's ' Geology of 
Sussex,' pi. xxi, fig. IG, as a "fragment of an Oreaxlcr." In Part III of this 
Monograph it was figured under my direction (PI. XXV, figs. G, (! <f) as Genus (?), 
Sp. (?). I have now isolated two or three ossicles from the specimen, and they 
are figured on PI. XXIX, fig. 9. They show that the ossicles as originally figured 
merely present their interior aspect. The specimen E. 501V> is taken as the type. 

15 



100 FOSSIL ASTEROIDEA. 

Description. — The state of preservation of tlie fragmentary specimens of this 
species only allows adequate description of the ossicles of the disc. These are 
very uniform in character, and only differ from those of Stciuranderaster ocellatus 
in the absence of the truncated summit with inadreporiform striations. The 
largest ossicle measures about G mm. in diameter. 

The isolated ossicles figured on PL XXIX show the characteristic shape of 
marginal ossicles belonging to the genus StanrdmleraHtur (see p. 120), and assist 
us in ascri]:)ing not only this species, but also /S. ocelldfns, to which the species is 
closely allied, to that genus. 

Localitij (iiid Btratigraphical Position. — The specimen pi'esented to the British 
Museum (Nat. Hist.) by Mr. W. McPherson, is from the Marsupites zone at 
Brighton. The specimens in the collection of Dr. Blackmore are from 
Micheldever, Hants (zone of Micraster cor-caujiilnum). 

OrJ.^r— CRYPTOZONIA, Sluh;,, 1886. 

Famihi—hmGKlYDM, Pnrier, 1875. 

Cryptozonate Asteroidea, with comparatively well-developed marginal plates, 
always contingent. Disc small, rays long and cylindrical. Abactinal skeleton 
tessellate. Tegumentary developments granulate, superambulacral plates usually 
present. Pedicellaria? (rarely present) excavate or foraminate. 



GeuHs—LmCKlA, Nardu, 1834. 

LiNCKiA, yardo, 1834. De Asteriis, Okeu's Isis, p. 717. 

Ophidiastek (pars), Miiller and Trvschel, 1890, Mouatsber k. preuss. Akad. Wiss. 

Berlin, p. 103. 
LiNCKiA, Gray, 1841. Auu. Mag. Nat. Hist., vol. vi, p. 284. 

AcALiA (sub. geu.). Gray, 1841. Tom. cit., p. 285. 

Arms more or less cylindrical. Dorsal plates small, not arranged regularly in 
longitudinal series. Two or three rows of granules on the adambulacral plates. 
Superambulacral plates present. Papular areas distributed irregularly between 
the dorsal plates. 

1. LiNCKiA, ? sp. PL XXVII, figs. 1, 1 a. 

MaU-rial. — A distorted specimen, which vei'y prol)ably belongs to the genus 
LiiicJcia, is preserved in the Briti.sh Museum (Nat. Hist.) (E. 5055, Capron Coll.). 



OPHIURA. lol 

Description. — The disc is siiiall imd wvy imicli distorted. The ventral 
aspect of one arm is tlie only portion of the star-fish which affords much 
opportunity for description. The ai-ni is al)out 18 mm. lonjf and 1- mm. broad, 
and possesses the C3'lindrical characteristic shape of the genus. It is composed 
of a h\rge number of square ossicles, which are superposed in the cross-section of 
the arm, so far as it can be seen. They possess no spines, but a regular granula- 
tion appears to run lineally across their breadth. 

Remarks. — This specimen is not sufficiently well ])reserved to ascribe it to a 
definite species of the genus. 

Strafiijraphical Position. — Lower Chalk. 



CRETACb:OUS OPllIUROIDEA. 

Order— ZYGOVEI\J'RM, Bell (1892). 

Ophiuroidea, in which the movement of the ossicles on one another is limited 
l)y the development of lateral processes and pits. Superior, inferior, and lateral 
spine-bearing arm-plates are always present. The arms are simple and cannot 
coil round straight rods. 



/<\,„i,7y_0l'HI0LEPIl)l D^. 

Zygophiura; with oral pa})illcB from three to six, of wliirli the last may bo 
infradental. Arm incisures on the disc. Dental papilUe absent. 



Ge«((.s— OPHIURA, Lamard; 1801. 

Ophiuka, Lamarck. Histoire Naturcllo des Auimaux siius Vortobrcs, vol. ii. 

Ophiolepis, Mailer and Tranclul, 1842. System tier Asterideu (HraunscLwcij?). 
Ophioglypha, Lyman, 1865. (OphiuridtD and Astrophytidtc) 111. Cat. Mus. Comp. 

Zool. Harvard, Nos. i, viii ; 1882, Kcp. Challenger Zool, 

vol. V. 
Verrill, 1899. Keport on the Ophiuroidea collected by the Bahama 

Expedition in 1893 ; Iowa City, Bull. Labor. Nat. Hist., p. 1. 

Disc covered with plates or scales which are for the most part swollen. 
Radial shields naked and swollen. Teeth. The inner niouth-papilhe long l)ut 

16 



102 FOSSIL ASTEROIDEA. 

becoming smaller and sliorter towards the distal oral region, where they are 
almost hidden In' the scales of the mouth-tentacles. Arm-spines smooth and 
short, seldom longer than an arm-segment. Tentacle-scales numerous. The 
innermost pair of tentacle-pores narrow, surrounded by numerous tentacle-scales, 
and opening obliquely into the oral slits. In the back of the disc, where the arm 
joins it, a notch usuall}' edged with papillae. Two genital slits arise from the 
sides of the mouth-shields. 

The following species are placed pi-ovisioually in this genus, to which the 
known chai'acters would approximate them. The evidence, however, in every 
case is incomplete. 



1. Ophiuea serrata, Boemer. PL XXVII, figs. 3, 3 a, Sb, S c, 3 d, 3 e. 

Ophiuea sebbata, Boemer, F. A., 1841. Die Versteinerungen norddeutsch. 

Kreidegeb., p. 28, pi. vi, fig. 23. 

— — Forbes, 1843. Proc. Geol. Soc, vol. iv, p. 234, fig. 2. 

— — Reuss, 1845-6. Die Versteiu. bobm. Kreide-fonu., vol. ii, p. 

58, pi. XX, fig. 26. 

— — Forbes, 1850. lu Dixon's Geology and Fossils of tbe Tertiary 

and Cretaceous Formations of Sussex, p. 337, pi. xxiii, 
figs. 2, 3, 3 o, 3 b. 

— — iiro)T(«, 1854. Cat. Brit. Foss., ed. 2, p. 84. 

— — Forbes, 1878. In Dixon's Geology of Sussex (new edition, 

Jones), p. 369, pi. xxiii, figs. 2, 3, 3 «, 3 6. 

Specific Gharactevs. — Conspicuous pear-shaped radials. Remainder of dorsal 
surface of disc covered with scales. Upper arm-plates occupying great propor- 
tionate width of arm. Six, occasionally seven ?, spines on each side of arm-segment. 

Material. — Only two fragments of arms were originally available for descrip- 
tion by Roemer. The specimens described by Forbes were more nearly complete, 
one specimen showing a considerable portion of the disc and the proximal portion 
of four arms (figured on PI. XXVII of this Monograph), now in the British 
Museum (Nat. Hist.), and bearing the registered number E. 5043 (Dixon Coll.). 
There are fragments of arms in several collections which can apparently be 
ascribed to this species. 

Description. — The disc is 15 mm. in diameter. Almost the Avhole of the dorsal 
covering has disappeared in the specimen figured, thus exposing the inner surface 
of the mouth-plates. The jaws (oral angle plates) are clearly seen. They are 
long and slender and do not meet inter-radially. The grooves for the water 



OPHTFRA PARYISENTUM. 103 

vascular canal and for the nerve-ring ; and the depressions for the first mouth- 
tentacle and the entrance to the branch of the water vascular system are clearly 
shown. Fragments of the scaly covering of the disc are seen scattered over the 
disc. The peristomial plates are not recognisable, as is also the case in modern 
S|)ecies of Ophinra. The arms are 3 mm. wide at the base. The upper arm-plates 
near the disc are broad. Six (or seven ?) spines, Avliicli are in IciiLrtli about a 
third of the length of the arm-segment, are present. 

The vertebral o.ssicles are figured on PI. XXVII, figs. 3r, o J, 3^. They show 
the typical Ophiurid structure as displayed by modern species of Zygophiurids. 

Locality and Stratigraplncal Position. — Upper C'lialk, Bromley, Kent. 



2. OiMiUTUA FiTCHii, n. sp., ex Forbes, :MS. PI. XXVII, figs. 2, 2 <i, 2 h. 

Specific Characters. — Body large and stoutly Ijuilt. Disc covered with largo 
swollen plates. Radials contiguous, largo, kidney-.shaped. Upper and lower arm- 
plates small. 

Material. — An external cast in flint, the sole remains of this species, is 
preserved in the Norwich Museum (Xo. 22'.t4). 

Description. — Very little can be made out concerning the structure of this 
ophiurid. The disc appears to have been surrounded with a circlet of large 
radials. It has a diameter of about IG mm. 

A plasticine mould of the lower portion of the cast is figured on PI. XXVII, 
fig. 2 (/. The jaws (oral angle plates) are distinctly seen. They were long and 
slender, and similar in form to those of 0. serrata. Similarly a peristomial plate is 
not visible. The inter-radial rounded buccal shield is clearly seen. The arm is 
45 mm. broad at the base. The impression of the cast of the arm appears to 
indicate that both upper and lower arm-plates were small, as the side arm-plates 
appear to meet in the dorsal and ventral median lines. 

Locality and Stratigraphical Position. — From flint gravel, Household, Norwich. 

3. Ol'HlURA PAEVISENTUM, n. sp. PI. XXVII, figs. 4, 4 a. 

Specifc Characters.— Disc covered with small plates, radials inconspicuous. 
Proximal upper arm-plates only occupying about one third of dorsal surface of 
arm. Five spines on each side of arm-segment. 



104 FOSSIL ASTEROIDEA. 

Matert'il. — There is only one specimen of tliis species. This is preserved in 
the British Museum (Nat. Hist.), and bears the registered number E. 5052 
(purchased of Simmons). 

Description. — The disc is about 15 mm. in diameter. It is covered with a large 
number of small plates, which are rather scattered. The arms are o mm. broad 
at the base. The upper arm-plate is much narrower than in 0. serrata. There 
are five spines, about three quarters the length of an arm-segment, on each side 
of the arm. 

LocaUtij and IStratiijrajjJucal Pos«7/o«.— Upper Chalk, Bromley, Kent. 



(7e„,ts— OPHIOTITANOS,' novum. 

Disc covered with plates which are small and sub-equal. Eadial shields small, 
triangular, naked, scarcely swollen. Arm-spines small. Mouth-shields large. 
Side mouth-shields small, widely separated. 



1. Ophiotitanos tenuis, n. sp. PI. XXVIII, figs. 1, 1 (/, 2, 2(7. 

Proximal upper arm-plates longer than broad. Spines very short, five in 
number. Disc, with the exception of the radial plates, covered with an extensive 
granulation. 

Material.— The material for the description of this species consists of several 
specimens in the British Museum (Nat. Hist.), The specimen E. 5056, which is 
the type, is figured on PL XXVIII, fig. 1, and the specimen E. 5057 on PL XXVIII, 
fig. 2. There are also specimens registered E. 5058, E. 5059, 57512. All are in a 
fair state of preservation. The first four specimens are from the Capron Coll., 
and the latter specimen was purchased from W. Griffiths. There are further 
examples of the species in the Sedgwick Museum, Cambridge. 

DescrijMon. — The disc is flat on the dorsal surface, and its diameter in the 
largest specimen is 4-7 mm. Each pair of radial shields is separated by three 
ornamented plates. 

The mouth-shields are almost oval in shape. The side moiith-shields are 
small, and lie widely separatetl on the outer edges of the mouth-shields. There 

' 'ri7ai<'c= chalk. 



Ol'TTTOTlTANOS L^VIS. 105 

is a large number of granules in the oral region, but the tips of the jaws (oral 
angle plates) can be seen just above the mouth-shields. There appear to be five 
(or six) squarish mouth-papillas. 

The first under arm-plate is small and ■with rounded edges. Distally the 
under arm-plates are at first almost square, then roughly pentagonal, and finally 
triangular, with the apex pointing towards the ilisc. The side arm-plates meet 
below at about the seventeenth arm-plate. The upper arm-plates are at first 
hexagonal, but rapidly become roughly triangular. They are tumid in appearance 
and have a rounded base. They rapidly become smaller, and allow the arm-plates 
to meet dorsally. 

There are on each arm-segment five small smooth sjiinos considerably shorter 
than the length of a segment. 

There appear to be two tentacle-scales, but the exact number is rather 
diflScult to determine. 

LocuUfy (I lid Stratigraphies] Position. — Lower Chalk, Folkestone and Dover. 



2. OriiioTiTANOS L.EVis, n. sp. PL XXVIII, figs. 3, 3 a, 4, 4 a. 

Specific Characters. — Spines longer than arm-segments. Upper arm-plates 
broader than long. Plates of dorsal surface of disc not hidden by granules. 

Material. — Only one specimen is known. This is preserved in the British 
Museum (Nat. Hist.), no. E. 5053 (purchased of Mr. Griffiths), and shows the 
dorsal aspect. 

Description. — The diameter of the disc is 4 8 mm., l)eing thus about the same 
size as Ophiutitanos tenvix. The arm is, however, not so broad at the base, 
measuring here only 1'5 mm. across. The specific characters given above 
separate it sharply from this last-named species. I have not been able to 
determine the number of spines on each arm-segment. 

Locality and Stratigrapldcal Position. — Lower Chalk, Dover. 

Remarks. — A small specimen upon the slab, no. E. 5058 (PI. XXVIII, figs. 4, 
4 a), may be a young member of this species, as it possesses a strong general 
resemblance to the above. It is peculiar in having only four arms, probably an 
abnormality. As explained on p. Ill, Ojihioijli/jihii hridiieronsis. Meek, is very 
similar in :ippearnncc to this species. 



106 FOSSIL ASTEROIDEA. 



3. Ofhiotit.o^os MAGNUS, 11. sp. PI. XXVIII, figs. 5, 5 rt ; PI. XXIX, fig. 13. 

Specific Characters. — Proximal upper arm-plates broader than long. Spines 
very short, seven spines on each arm-segment. Disc, with the exception of the 
radial plates, covered with an extensive granulation. 

Material. — There are several sjiecimens Ijelonging to this species in the British 
]\Iuseuni (Nat. Hist.) and in the Sedgwick Museum at Camliridge. The specimens 
in the British Museum bear the registered numbers E. 50G0 (Capron Coll.), E. 5050, 
E. 370, and E. 371 (all from J. Starkie Gardner Coll.). The first-named speci- 
men, which shows the ventral aspect, is figured on PI. XXVIII as the type. A 
specimen from the Sedgwick Museum showing the dorsal aspect is figured on PI. 
XXIX. 

Description. — This species is the largest of all the known Chalk Ophiuroids, the 
diameter of the disc being about 37 mm., and the breadth of the arm at the base 
5 mm. There appear to have been two tentacle-scales. 

Beuiarl-s. — Portions of the arm of this species are very similar in form to those 
of Ojihiura serrata. Unless the disc is present it is difficult to separate this 
species from that form. 

Localiti/ and Stratiijraphical Position. — Lower Chalk. 



<SH.6-orcZer— XECTOPHIUR^. 

Spines situated at an angle to the arm. 

F.n/H7//— AMPHIURID^, Ljungman, 1867. 

Zygophiurje with oral papillae from one to five, of which the last is generally 
infradental. Arms inserted on ventral side of disc. Dental papillae absent. 

6'eH,HS— AMPHITJRA, Forhes, 1842. 

Disc small, delicate, covered witli naked overlapping scales, and furnished 
with uncovered radial sliiclds. Teeth. Mouth-angles small and narrow. Arms 
long, slender, even, and nunv or less flattened. Arm-spines short and regidar. 



KXTRA-HKITISII AS'I'KKOI DMA. 10? 



1. AMrnUHiA CEETACEA, 11. s|). 1*1. X.W'ill, fig.S. (i, (i (/. 

Specific C/ia meters. — Five (oi" six) mouth-papilho. Two tL'ntaclc-.scak's. Five 
arm-spines. Moutli-sliields triangiilai' in shape with a curveil convex base, a 
fair proportion of the jaws (oral angle plates) showing on the ventral surface. 

Maierud. — The one .specimen known of this species is preserved in the Britisli 
Museum (Nat. Hist.), no. E. 5059 (Capron Coll.). 

Description. — The disc is o mm. in (liaiucter. 

There are five (or six) moderately stout blunt mouth-papilla; on either side of 
the mouth-angle, and a triangular papilla situated infradentally. The side mouth- 
shields are long and narrow, with proximal and distal sides parallel. They meet 
in the middle. The extremities of the jaws are very obvious above these. 

The arms are long and slender, and are 2 mm. broad at base. The wiiltli of 
arm close to disc is 1*6 mm. The first under arm-plate is small, with slight 
re-entering sides and a prominent median groove. The remaining under arm- 
plates have a pointed proximal apex, and their sides are re-enteringly curved. 
The distal side is convex. The side arm-plates meet proximally on the under 
surface in the middle line. 

The five stout tapering spines arc rather longer than a joint of the arm, and 
are situated on a proximal ridge. 

Localitij and Stratigrapliical Positiun. — Lower Chalk, Folkestone. 



CRETACEOUS ASTEROIDEA AND OPHIUROIDEA FROM 
EXTRA-BRITISH LOCALITIES. 

The following are the principal species from extra-British localities which 
have not been mentioned in the previous portions of the Monograph. It will be 
seen that where accurate information is available, these species are almost entirely 
identical with British species. 

AsTEiMAS QUINQUELOBA, GoliJfuss, 182G. ' Petrefacta Germauia',' p. 200, pi. Ixiii, 

figs, ha — H. 

The illustrations given of this species are very beautiful and accurate, and 
enable one to identify the ossicles ascribed to it as a mixture of ossicles of 



108 FOSSIL ASTEROIDEA. 

Metopaster Parlcinsoni {a — p), Stauranderaster oreUatns {q — r), and rcntaijimader 
mcgalopJao; (s — v). 

Various German writers liave utilised the description of Goldfuss and this 
specific name for the identification of isolated ossicles — e.g. in Roemer, 18-il, 
' Die Verstein. norddeutsch. Kreidegeb.,' pi. vi, fig. 20, the ossicles ascribed to 
A. quinqiu'loba are really ossicles of P. megaloplax; while in Reuss, 1845 — 6, 
' Verstein. bohm. Kreideform.,' p. 58, pi. xliii, figs. 15 — 20, and in Geinitz, 
1872 — 5, ' Palfeontographica,' vol. xx, pt. 2, pi. vi, fig. 7, the ossicles ascribed to 
A. qiunqaeloha are really ossicles of M. Farkiiisoiii. 

Since the name qninqneloba is prior to all the other names mentioned above, it 
must be used instead of one of them. The simplest course appears to be to limit 
it in the sense of Roemer, by fixing on the specimen represented in Goldfuss's 
plate Ixiii, fig. 5 f, ii, as type of Aster ias quinqueJoba. The result of this is to 
replace the name Pentagonaster megaloplax, Sladen (antea p. 27, PI. IV, figs. 2 — 4, 
Rl. XIII, figs.l (I, 1 /'), by Pentagonaster quinqni-lobn (Goldfuss). 



AsTERiAS JUBENSis, Mitiister, 1826. In Goldfuss, ' Petrefacta Germania;,' p. 210, 

pi. Ixiii, figs. 6 a — /(. 

Figs. 6 a — e represent a fragment and isolated ossicles which closely resemble 
Callldcrma SmitJtix, and figs. G/ — h represent isolated ossicles bearing an equally 
strong resemblance to Stauranderaster Boysii. The species, however, is said to be 
"e calcareo jurassi Wurthembergia et Barutliino," whereas G. Smitliia} and 8. 
Boysii are typical Cretaceous species, and have not in any other work been 
described from Jurassic rocks. Without seeing the original specimens no one 
should assert that Miinster was so far mistaken as to the hoi'izon and locality of 
the fossils before him. We can only suspend judgment. 

AsTERiAS TAUULATA, Goldfuss, 182G. ' Petrefacta Germania^,' p. 210, pi. Ixiii. 

figs. 7 a—g. 

Figs. 7 a — h are illustrations of isolated ossicles of Stauranderaster argus 
which are found in the Upper Chalk (zone of Micraster. cor-anguinum). I am 
luiable to recognise the illustrations of the remaining ossicles as appertaining to 
any English Cretaceoiis species. The plates are said to be " e stratis argillaceis 
superioribus calcarei jurassi Baruthini." It is just possible that the locality and 
stratigraphical horizon are Avrongly given in the case of a and b, and the name 
Asterias tabula ta should be restricted to figs, c — g, one of those specimens being 
taken as type. 



KXTRA-BniTTSTT ASTEROmEA. 109 



AsTEItlAS Srnri.zii, Caffn. 

This is (lescril)e(l ami figured in Roemer, IS^-l, 'Die Verstein. Norddeiitsch. 
Krcidegeb.,' p. 28, pi. vi, fig. 21,asfolloAys : " Fiinfeckig niit fi'inf kurzen Strahlen, 
uiiteii voi'tieft und in der Mitte mit fi'inf Erliabcnlieiten ; dor vorstolicnde Rand 
gewc'ilbt mid zwischen jo zwci Strahleuspitzen mit etwa l-j selimalcn Tiifelchen 
besetzt." 

The description reads as if the .specimen belonged to the genus Staurauderaster, 
but neither this nor the figure given is much aid in the exact identification of the 
species. 

A cast of a fossil Asteroid is ascribed to the same species under the name of 
Slellaster Schthii, In- Geinitz, ' Pala^ontographica,' vol. xx, pt. 2, pi. v, figs. 3, 4. 
Tliis cast, however, looks like a cast of a species of either Callldenna or 
Nymjihaster. 

AsTERiAS? DcNKEKi, Roemev, 1841. 'Die Verstein. norddeutsch. Kreidegeb.,' 

p. 27. 

This species is described as follows : " Die Fliichentiifelchen sind liinger als 
breit, 4—6 eckig, schriigrandigfein gekornt und nahe am obcrn Rande durchl)ohrt.'' 
Only isolated plates were known. I am unable to identify- the species with other 
known Asteroids. The illustration given is not very clear. 

According to Roemer, these isolated plates were described by Dunkcr and 
Koch, 1837, ' Norddeut.sch. Oolithgeb.,' as plates of Ciihiris rarialiilin. 

CiEr.ASTKR CouLONi, AijasK}::, 183(). 'Mem. Soc. Sci. Nat. Nciiclinfcl,' vol. i, p. 101. 

No figure was given of this species by Agassiz. A fossil Asteroid figured by 
Fritel, ' Le Naturaliste,' vol. xvi, 1002, p. 70, as tliis sjx'cics, iiiijiriu-s to be some- 
what like Nymphaster innrf/ivatiis. 

CuPi'LASTER PAiPER, Fiir, 1893. ' Arch. Lande.'idf. Bohmen,' ix, no. 1, p. 112. 

This species is named from a specimen 3 mm. in diameter, which so obviously 
presents the large terminal plates which are common to all very young forms 
of starfish, that it is useless to speculate as to its identity. 

Laraliti/ and Slfiitii/nijiliind rusUion. — Cretaceous (Prie.'^cner Schichten), 
Waldek, near Bensen, Bohemia. 

17 



110 FOSSIL ASTEEOIDEA. 



GoNiASi'ER MAEGINATUS, Beuss, 1845 — 6. ' Verstein. bobm. Kreideform.,' p. 58, 

pb 43, figs. 21—32. 

Tbe illustrations of tbe isolated ossicles described as this species bear strong 
resemblance to tbose of M. Parkinsoni. 



Goxi.vsrER 3iAii.MiLLATA, GiM, described by Clark, 1892, in 'Bull. U.S. Geological 

Survey,' no. 97, p. 32. 

" Determinative Gharadei-s. — Body pentagonal, provided witb a dorsal and a 
ventral row of marginal plates that are narrower than high, and distinctly tumid 
on their outer surface. Only detached marginal plates preserved." 

Bemarhs. — The isolated plates undoubtedly belong to a species of Pi/cinaster 
and bear a strong resemblance to those of Pijcinaster angustatus. 

" Locality and Geological Position. — Yellow Limestone of the middle marl bed 
of the Cretaceous from Vincentown, New Jersey." 



Pentaceros dilatatus, S. Meunier, 1906. ' Le Naturaliste,' (2), vol. xx, p. 117. 

The specimen described under this name is an external cast in flint, of which 
a plaster cast has been presented to the British Museum (Nat. Hist.), E. 13075. 
Owing to the courtesy of Professor Stanislas Meunier I have been able to examine 
the original specimen. It shows a well-preserved impression of the abactinal 
surface. The ossicles of the disc are rhomboidal or hexagonal, contiguous, of 
almost uniform size, about 2 mm. in diameter. The specimen, therefore, cannot 
be placed in the genus Pentaceros, and its appearance, measurements, and type 
of ornament enable me to ascribe it to Pentagonaster obtusus. 



Ophioglypha beidgerensis, Meel; described and figured by GlarTc, 1892. ' Bull. 

U.S. Geological Survey,' no. 97, p. 29. 

^Determinative Characters. — Disc composed of numerous small imbricating 
plates. Upper arm-plates Avider than long, the outer angles sharp and expanding 
between the side arm-plates, which are slightly smaller. Under arm-plates long 
and nearly rectangular in shape. 



EXTRA-BRITISH ASTEROIDEA. Ill 

" ]>i mentions. — Diameter of disc iimi. Length of arm 20 mm. Width of 
arm near disc 1'25 mm." 

Rpmarkx. — The figures given and dimensions of this species appear to me to 
indicate tliat it closely resembles Ophiot'itanos Ixris. The upper arm-plates are 
described as hexagonal, and the more proximal upper arm-plates of the British 
species present this appearance. 

Localitij and Stvatigraphical Position. — Cretaceous, Fort Ellis, Montana. 



OriiiO(ii,YriiA TioxAXA, Clad; 1892. 'Bull. U.S. Geol. Survey,' no. 97, p. oU. 

"Determinative Characters. — Disc round; composition indistinct. Arms long, 
with wedge-shaped under ai'in-plates about as wide as long; upper ann-plates 
about twice as wide as long. 

" jD/jhc»6v'oh.s-.— Diameter of disc 15 mm. Length of arm 5() mm. Width of 
arm at disc 2 mm." 

Iiemarl-s. — It is difficult to identify this with a British species, but the illus- 
trations appear to indicate that it is somewhat similar to Awphinra cretacea. 

Localiti/ and Stratiijyajjhical Position. — Cretaceous, six miles north of Fort 
AVorth. 



OriiiriJA OKANn.osA, Tuicno'r, 1841. 'Die Verstein. norddeutsch. Kreidegeb.,' yi. 

28, pi. vi, fig. 22. 

This species is described as follows : 

" Die Arme sind walsenformig und bestehen aus gewolbten, seitlich durch ein 
Furche getrennten, deutlich gekornten Seitenschildchen ; wo sich deren vier 
beriihren liegt ein kleines, dreieckiges Sehildehcn da/.wischen." 

Rcmarls. — The small fragment of the arm figured shows it to be a portion 
of the distal extremity— cpiite possibly (he distal extremity of some species of 
OjMotitanos. 

JjOcaVifij and Slrafiijrajihical Position. — Lower Chalk, Liudener Berg, near 
Hanover. 



1]2 FOSSIL ASTEROIDEA. 

Oi'iiiiKA r riJ.CHEEiiiMA, Fnc, 1893. 'Arcli. Laudesdf. Bohmen,' vol. ix, no. 1, 

p. 113. 

neinarJcs. — Xo description is given. The figure does not show any resemblance 
of this species to other known forms, but the specimen was obviously imperfect. 
The upper arm-plates appear to be V-shaped. 

Localitij and Strati graphical Position. — Cretaceous (Priesener Schichten), 
Waldek, near Bensen, Bohemia. 



Stellaster ALBENSis, Geinit::, 18/2 — 5. ' Pala^ontographica,' vol. xx, jit. 2, p. 1(3, 

pi. vi, fig. 3. 

ItemarJis. — This species is only known from a cast from the Quadersandstein. 
In the absence of determinative characters it is impossible to say whether it is 
identical with or differs from more full}' described species. 

Steli.aster CooMrii, Furies, sp., in Geinit::, 1872 — 5, ' Pal^ontographica,' vol. xx, 

pt. 2, p. 17, pi. vi, figs. -1—6. 

The specimens illustrated here as S. Goomhil certainly do not belong to Forbes' 
sjjecies of that name. They appear to be ossicles of various species, but I am 
unable to identify them from the figures given. 



SPECIFIC AND GENERIC CHARACTERS IN CHALK ASTEROIDEA. 

When I connnenced this account of Cretaceous Asteroids I endeavoured, so 
far as possible, to follow the generic classification of previous authors and 
especially to preserve the continuity of Mr. Sladen's work. More recent work, 
however, has led me to believe that the shape of the marginal plates, together 
with their ornament, affords the best determinative generic and sjiecific characters, 
and further enables ns to identify almost all Cretaceous starfishes from single 
isolated plates. 

Some necessary revision as to nomenclature in both genera and species is given 
below, together with an illustrated key-table, which it is hopeil will enable zonal 
collectors to identify the isolated asteroid [ilates which are commonly met with in 



ASTKKOIDKA. 



113 



almost all exposures. Up to the present oui- knowledge of the zonal occurrence 
of these forms lias heen limited, as complete specimens of starfishes are exceed- 
ingly rare. There appears to be no reason now, however, why our knowledge 
of the zonal distril)ution of these forms should not become as nearly complete as 
it is, for example, in the case of Echinoiils. 

I must thank Dr. Blackmore, of Salisbury, for his invaluable suggestions to me 
concerning this means of identification. 




Tbxt-fio. 3. — Isolated marginal of 
tfymphaster Coombii, showing spines 
and spine-pits. 



Oriiiiment. — The ornament of starfishes consists of calcareous jjieces, which 
may be spinous in form, or scaly, or granular. These may occur : 

(1) Emliedded in the living tissues outside the general body-plates, but not in 
contact with the plates themselves. Oh the death of the animal they become 
dis[)ersed on the disintegration of the living tissues, and such ornament is therefoi'e 
rarely visible in fossil specimens. 

(2) Articulated to the plates. In this case they are situated : 

((() Either in a depression of the plate ; 
{b) Or in a depression upon a raised eminence 

of the plate. Occasionally in this latter case 
the depression may be excavate in the centre 
in order to allow a strong muscular attach- 
niL'ut. In this case the eminence may 
simulate the perforate tuliercle of an Echi- 
noid such as Cidarii. 
In almost all cases in Cretaceous Asteroids the 
ornament is of the type 2 a. 

Generally the movable articulated pieces have 
disappeared, but in such cases the depression on 
the plate which they formerly occupied is readily 
visil)Ic (coini)are Text-fig. 3). 

i purpose to call all such movable articulated 
pieces, whether they are spinous or granular in 
character, "spines," and, at the suggestion of 
Dr. Jiather, the depressions on the plate " spine-pits." 
The character of the spine-pits appears to be 
constant in character in each individual species. 
Thus, e.(j. in N. Coomhit (Text-fig. ;3) they show a coarse honeycomlj structure, 
uniform in character over the whole of the plate. In Sfdiiramhrastrr l>iilhlj\nis 
(Text-fig. 4) the spine-pits are circular and widely s|)aced. This latter type is 
interesting, as it apparently occurs only in the genera MckqMstcr aiul Shninni- 
derasfer. The spine is Very small, and barely projects over the edge of the deep 





Tkxt-fio. 4. — Isoliited inarginiil of 
Staurandernstt'r InilhiJ'erus, showing 
the " pustulate " type of ornauient. 



lu 



FOSSIL ASTEROIDEA. 



spine-pit, tlius giving the plates an embossed appearance. This type of ornament 
I call the " pustulate " type. 

In previous portions of this Monograph both Mr. Sladeu and myself have 
assumed that if no spine-pits are present on a plate they have been weathered 

away. It now appears that the absence 
of spine-pits is such a constant character 
in certain species that this supposition 
can no longer be held, and the absence of 
spine-pits indicates an original absence 
of spines, or, at any rate, spines articu- 
lated to the plates. In support of such a 
conclusion it can be urged that, generally 
speaking, Chalk fossils are but little 
Aveathered, and that there is evidence 
derived from a study of recent forms. 

Pedicellariae. — As can readily be under- 
stood, only pedicellari^ which are articu- 
• -^-i^^MJs lated in depressions of the plate are pre- 

"^ "^ served in Cretaceous Asteroids. Purse- 

like, valvate pedicellarijB (Text-fig. 5) 
of a generalised tj'pe are common to 
man}" genera. More specialised pedicel- 
lariae, however, peculiar to the genera Metopastcr and Pi/clnastcr are also met 
with (Text-fig. 7). 



Text-fig. 5. — Pedicellaria of A'i/i)i/i?ias(er 
oUgoplaz. 



I ' 



Text-fig. 6. — Tliree pedicellaria from Penfago- 
nustcr quinqueloha on the rio;ht. A pedicellaria 
from Hadranderaster aobreviatus on the left. 



Text-fig. 7. — A pedicellaria from Metopaster 
PurJiinsoni in the centre, on the left a pedi- 
cellaria of Pycinaster senonensis, on the right a 
pedicellaria of Stanranderaster coronat^is. 



KEY-TABLE FOR THE IDENTIFICATION OF CRETACEOUS 

ASTEROIDS. 



The following key-table is based on the shape of the marginal plates and the 
character of the spine-pits on them. Generally speaking both superior and 
inferior series are similar in these respects, but when otherwise a note is made in 
the table. 

A short description is also given of various plates which cannot be adequately 
treated in the table. 

All the plates figured in the table are magnified 4 diameters. 

It is convenient to consider the Chalk (Cenomanian-Senonian) species 
separately from the Upper Greensand forms. No Cretaceous Asteroidea liave 
been described from below this horizon. 



KKV-TABLE. 



115 



Chalk (Cknomanian-Sexoniax) Si-ecies. 
r. — Marginals four-sided, with sides rectilinear or almost rectilinear; broad. 

A. Without a rabl)et-edge. CallUlenna, Nijmphastcr, I'eiitagonaster. 

B. With a rabbet-edge. Metopaster, MUrasfry. 
c. With a distinct ridge. Artkraster. 

II. — Marginals either hexagonal or rounded; very thick. Iladranderaster. 
III. — Marginals wedge-shaped, high, spine-pits very shallow or absent. Pijcinaster. 
IV. — Marginals breast-plate-shaped. Staiiramle raster. 

Y .—Miscellaneous plates. 



I. — ^Marginals fom'-sided, with sides rectilinear or almost rectilinear. Pedi- 
cellarise when present of a simple bi-valvate character. 

A. Without a rabbet-edge. Calliderma, Nymphaster, I'entdyonaster. 

1. Spine-pits shallow, hexagonal, giving a honeycomb appearance. 



(A) 



(B) 



■^ 




Text-fio. 8. 




a. Honeycomb medium ortiiio. C.Smithiie (see p. 123). 
Text-fig. 8 a. — Variety with iiieilium-sized spiue-pits 

(see p. 123). 
Text-tig. 8 B. — Variety with iiae spiue-])its (see 

p. 123). 



b. Honeycomb coarse. N. Cooiiibli. Text-fig. 3, p. 113. 



c. Honeycomb confined tt) a portion of the plate (or 
absent). P. iibtiisuK. Text-tig. 9. 



T«xT-rio. 9. 



IIG 



FOSSIL ASTEROIDEA. 

2. Spine-pits shallow, cii-ciilar, circles variable in size, adjoining. 




One species, C. lafirm. Text-fig. 10. 



Text-fiq. 10. 



3. Spine-pits deep, circular, not adjoiniug. 



a. Spine-pits coarse. N. marginatus. Text-fig. 11. 

6. Spine-pits fine, not on margin. N. oligoplax. Text-fig. 12. 



Text-fjo. 11. Text-fig. 12. 




c. Sprue-pits fine, uuiforruly over tlie vliole of plate. P. lunatus. 
Text-fig. 13. 



Text-fio. 13. 



4. Spiue-pits on outer edge of plate with raised margins. 




One species, P. quinqtieloba (see p. 108). Text-fig. 14. 



Text-pio. \l. 



KEY-TA1{I>K. 



117 



5. No spiue-pits present. 



(A) 



(B) 



Text-pig. 15. 



((. Pro.\iiiial inargiualia almost smooth ; distal 
with <,'raiuilari-iii,'osities arranged iu a linear 
series. N. railiatiig. Text-fig. 15, (a) pro- 
ximal marginal, (b) distal marginal. 




b. Marginalia with rugosities not arranged iu 
linear series. N. rugosus. Text-fig. 16. 



B. ilarginals with a ral}bet-edgo. Ealjbet-edge covered with small spine- 
pits, redicellariie when present " winged " (see Text-fig. 7). 



(A) 




1. Spiue-pits on central raised area. 

(B) 




Text-kio. 17. 



(B) 



(A) 



-"3»r*r 




a. Central raised area smooth on both sufierior 
and inferior marginalia. Spiue-pits on 
infero-margiualia uniformly situated. M. 
Parkinsoni. Text-fig. 17, (a) outer view 
of marginal, (b) side view of marginal. 



h. Central raised area of supero-marginalia 
rugose ; that of infero-margiualia smooth, 
with spiue-pits iu form of network. M. 
Hiinteri. Text-fig. 18, (a) supero-marginal, 
(b) iufero-margiual. 



c. Central raised area of supero-marginalia 
smooth in young, rugose in mature indi- 
viduals. Lower Chalk form. M. coriniliie 
(see J). 124). 



Text-kio. is. 



18 



118 



FOSSIL ASTEROIDEA. 



2. No spine-pits on central raised area. 

(A) (B) 




-i 



Text-fig. 19. 





a. Kugosities present on greater portion of surface 
of supero-marginalia. If. rugaius. Text-fig. 
19, (a) supero-marginal, (b) infero-inarginal. 



6. Rugosities confined to inner edge of supero- 
marginalia or absent; outer portion of plate 
tumid, a. Plates oblong. If. uncatus. Test- 
fig. 20, (a) supero-marginal, (b) iufero-mar- 
giual. /3. Plates square, if. qiiadratus. 

c. No rugosities present ou the supero-marginalia 
which are not tumid on their outer portion. 
M. compacfus. See PI. XXVI, fig. 3 b. 



Text-fig. 20. 
N.B. — Tlie infero-marginalia of the above species are diflicult to distinguish except by 
their dimensions. The reader is advised to refer to the detailed description for these. 



c. Marginalia Avitli a distinct ridge wliicli lias granular elevations along 
its base. Jiihraster. 

(A) (B) 



1. Upper surface of ridge smooth. A. Bizoni. 

Text-fig. 21, (a) outer view of marginal, (b) 
side view of marginal. 

2. Upper surface of ridge with spine-pits. A. cris- 

tatiis. See PI. XXIX, fig. 10. 




Text-fig. 21. 



II. — Plates either hexagonal or rounded ; very thick. Spine-pits form a distinct, 
fine honeycomb marking. Hadranderaster (see p. 12-5). 



(A) 



(B) 




There is only one species. H. abhreviatus. Text- 
fig. 22, (a) outer view of marginal, (b) side 
view of marginal. 



Text-fiq. 22. 



KEY-TAHLH. 



ll'.t 



III. — Marginals generally wedge-shaped, high, spine-pits very shallow or absent. 
Pedicellariae when present with five valves round a deep central 
depression. Pi/ciiiaster. 



1. Platos of maximum heit^bt, 10 

mm. P. angugtatug. See PI. 
IX, fig. 1 a. 

2. Platos of maximum lieifjlit, 20 

mm., p -shaped iu profile. P. 
senonensis. Text-fig. 23, (a) 
outer view of marginal, (b) 
interior view of mar<i;inal, (c) 
side view. 




Text-fio. 2.3. 




Text-fio. 24. 



3. Plates very thick, often oblong, 
not wedge-shaped. P. craggtis. 
PI. XXIX, fig. 3, exterior view 
of marginal. Text-fig. 24, side 
view of marginal. 



rV. — Marginal plates breast-plate-shaped. Stanranderaster (see p. 125). 
A. With .spine-pits. 








1. Spine-pits fairly coarse. S.hul- 

hiferug (commonly occurring). 
Text-fig. 25. 

2. Spine-pits medium. S. bipvnc- 

tatvs (only one specimen 
known). Text-fig. 26. 



Text-fio. 25. 



Text-fio. 26. 



120 



FOSSIL ASTEROIDEA. 




Text-fio. 27. 

c. Without spine-pits. 




Text-fig. 29. 



Text-ho. 28. 



3. Spine-pits fiue. S. Boijsi. Text-fig. 
27, (a) outer view of marginal, (b) 
interior view of marginal. 



1. Maximum size about 7 mm. S. coro- 

natus. Text-fig. 28. 

2. Maximum size about 25 mm. S. 

squamatus. 

3. Maximum size about 25 mm. 8. 

jnstiUi/erus. Text-fig. 29. 
N.B. — It is impossible to distinguish 
isolated marginalia of these two species. 
Compare V, 3 (p. 121). 



V. — T]t£ collector may also come into possession of tJw following plates : 

1. Large triangular plates liaving the characteristic ornament of Metopastcr. 
These are the ultimate supero-margiualia which characterise the genus. See e. g. 
PI. XVI, fig. 2 a. 

2. Large hemispherical plates with a flattened base. These are met with in 
the following species : 

A. With spine-pits. 

Stauranderaster hulbiferus, S. Boijsi, 
and ? S. hijiiiticfatiig. These are 
distinguished from one another 
hy their spine-pits, which are of the 
same character as those met with 
in the marginalia. Text-fig. 30= 
a primary inter-radial of S. hulbi- 
ferus. 

B. Without spine-pits. 
Pycinaster senonensig, distinguished by 

the smooth surface, PL XXIX, 
fig. 6. 
Arthraslcr Dironl, distinguished by the 
rugose surface, PI. XXIX, fig. 11. 




Text-fm. 30. 



KKV-TAIJIJ-;. 121 

3. Nodular plates with an excavate margin met with in the following species : 

A. A\'ith flattened base, from 7 — 9 mm. in diameter, S. coronal ui^, PI. XXIV, 

fig. 2. 
„ „ ,, o — I- mill. ,, S. squamfitui^yVl.XW, 

fig. 3. 
r. AVilli produced base, )S'. pistilllferHn, PI. XXV, fig. 5. 

4. Oblong or almost oblong plates having the characteristic ornament of ti. 
hitlbifents. These are the more distal marginals, or in some cases the ventro- 
lateralia of this species. Generally the marginals are indented at the corners, and 
their shape can be decided fi'om the characteristic breast-plate form. 




Text-fig. 4, p. 113. — Outer view of plate. 
Text-fig. 31. — Side view of plate. 



Text-pig. 31. 



5. Irreo'ularlj rounded or polygonal i)lates with occllate depressions having a 



raised ridge. 




A. Without madreporiform markings on summit. S. argus. PI. XXIX, 

fig. 8 a. 

B. With madreporiform markings on summit. S. ocellalus. Text- 

fig. 32. 



Tbxt-fio. 32. 



6. One specimen of Astroprctrn? sp. and LiucLin. sp. ? respectively have also 
been described, see pp. 90 and 100. 

Urrr.ii Gkeensand Foums. 

The genus Comptonia appears to be characteristic of this horizon. Tlie plates 
are very similar in shape to those of Cullulcruut, except that tlicy are more 
rounded in profile. Unfoi-tunately, no specimen at present known shows the 
ornament of the marginalia. 



122 



FOSSIL ASTEROIDEA. 



I have also met with G. Smithias and P. j^undatus from this horizon. They 
are readily distinguished by the characters ^vhich have already been given in 
the key-table. 



NOTES ON THE KEY-TABLE. 



Genera — Callidekma, Nymphaster, Pentagonastee. 



The follc^ving are the chief distinctive characters which separate these three 
genera in recent forms. 

Callideema. 

1. Anns well produced. 

2. Abactinal area covered with closely 

fitting plates. 



Pentagonaster. 
Arms slightly produced. 
As in CaUiderma. 



Ntmphasteb. 
As in CaUiderma. 
Abactinal area covered with 
paxilloe, which are not 



closely fitting in the radial 
areas. 



3. Ventro-lateral and infero-marginal 

plates with prominent spines. 

4. Armatui-e of the adambulacral 

plates consisting of 14-16 small 
spines arranged uniserially, 
with three or four rows of 
larger spines arranged rather 
irregularly. 



Ventro - lateral aud iufero - 
marginal plates without 
prominent spines. 

Armature of the adambu- 
lacral plates arranged in 
longitudinal series. Series 
on the whole uniform in 
character. 



As in Pentagonaster. 



As in Pentagonaster. 



The fossil species of CaUiderma possess the characters numbered 1 and 2, but 
differ to a greater or less extent in characters 3 and 4, in which they resemble 
Pentagonaster. The genus CaUiderma was, however, founded by Gray on one 
species — C. emma. No other recent species has been assigned to the genus. It is 
difficult, therefore, to say how far the distinctive characters of the Cretaceous 
genera should have generic value. The question is debated by Mr. Sladen on p. 5 
of this Monograph, and the very striking general resemblance of the fossil species 
to the recent G.'emma influenced him in his decision to group them under this 
genus. There appears no great reason to dispute this assignment, but I am in 
more doubt as to the systematic position of the species which have been placed in 
the genera Pentagonaster and Ni/mjdiaster. It will be seen that as the fossil 
species of CaUiderma resemble Pentagonaster in characters 3 and 4, the onlj- 
distinctive character which remains between the two genera is the length of the 



.NOTES ON GENERA. 123 

arm. Two of the fossil species of Fentagonastcr, namely 1'. hiudtus and obliisiis, 
have all arms which are well produced (the arms in the specimen of P. lunatus 
figured on PI. IV, fig. 1, are broken off short). The third and remaining species, 
1'. qiiinqaeloha, is usually much more pentagonal in shape, although a specimen in 
the possession of Dr. Blackniore has a major radius at lea,st twice the magnitude 
of that of the minor radius. 

The species assigned to the genus Nym2)hash'r by Sladen were so assigned 
because their structure and character, so far as they could be made out from the 
fragmentary condition of the fossils, appeared to warrant their inclusion in the 
genus Xi/niphasfcr (see jd. 15). 

It appears to me that these species have the same generalised characters as 
those assigned to the genera L'alliderma and rentiujonanter. The distinctive 
character of the genus Nijmpknster is the possession of paxilla? on the abactinal 
plates. No fossil species is suflBciently well preserved to show whether these were 
absent or present, and it is impossible therefore to confirm or deny Sladen's 
suggestion. 

DO 

It will be seen from the above tliat there is no certain evidence which entitles 
us to distribute the Cretaceous species amongst the three genera, and it may be 
the task of a future observer to phice tlieni in one new genus. I luive, however, 
in order to secure uniformity, utilised all these generic names even for the 
description of new species. The following species also appear to re(iuire revision. 

Callidenna Smithiae, C. mosaicum. 

After examination of the fairly numerous specimens of the fossils assigned to 
these species in the British Museum (Nat. Hist.) I cannot confirm the specific 
distinctions made by Sladen on pp. 10 and 11 of this Monograph. All the 
characters mentioned vary greatly in individual specimens. The ornament, 
however, is common in character to both species, and I should prefer to unite them 
in one species, namely, C. Smithiai, as this has prior place in the original account 
given by Forbes. 

The specimens figured on 1*1. VII, figs. 1 and 2, and stated by Sladen to be in 
his opinion doubtful examples of iV. Coombii (p. 17), should in my opinion be 
assigned to C. Smlthix, as should also the specimen figured on IM. XIX, fig. 3. 
The.se examples po.ssess a finer type of honeycomb structures on their marginalia 
than is usually met with in G. Smithisc, and they may, therefore, be a distinct 
variety of this species (see Text-fig. 8). 

A specimen preserved in the British Museum (Nat. Hist.) E. oOG3, was figured 
by Sladen on I'l. V, fig. 1 ", of this Monograph as Tuinidotitcr sulca(n.s. Apparently 
it was the intentiuii of Sladen to make a new genus and species for the rece])tion 



124 FOSSIL ASTEROIDEA. 

of this fossil. The dimensions of the marginalia, compared with the minor radius 
and the ornament, are precisely the same as in C. Smithiw, from which the 
specimen only differs in the possession of numerous valvate pedicellarige. In view 
of the somewhat freakish way in which pedicellariaj occur in starfishes, it does not 
appear to me that this character alone entitles us to make a specific or generic 
distinction on behalf of this specimen. 

There is another specimen also in the collection of the British Museum (E. 11 IG) 
which has similarly numerous valvate pedicellarise, but which shows the abactinal 
aspect. In all other respects the specimen cannot be distinguished from a 
specimen of G. Smith ise. 



Genus — Metopastee. 

In the key-table I have only distinguished four species of Metopaster, namely, 
M. Parlcinsoni, M. uncatus, M. quadrafus, and M. cornidus, the latter being a 
doubtful species. If one examines collections of Cretaceous Asteroids, one finds 
that jiractically all the specimens have been rightly assigned to these species. 
Specimens which could be assigned to the species M. MantclH, M. Boicerhanki, 
M. zonatas, M. siihhuiatus, M. ciiK/ulatKS (see pp. 38-55), are very rarely met with. 
The very considerable variation which occurs in undoubted specimens of 

M. ParJcinsoni in the number of the supero-mar- 
ginalia, their form, amount of ornament, and the 
shape of the ultimate plates of this series, makes 
specific characters founded solely upon these charac- 
ters of doubtful validity, particularly as such varia- 
tions occur even in an individual specimen, and it 
,,„".,,„, is upon a rather extreme variation of these charac- 

Text-fig. 33. — Marginal of Sleto- ^ 

paster Parkinsoni, shovnngn more ters occurriuo- in vcrv fcw spccimcns that this large 

scattered tj^pe of ornament than . . 

that usuaUy met ^rith. number of specics have been described. On the 

other hand, the presence or absence of spine-pits on the raised central area of the 
plate is a constant character in species of Mdopastcr. Tavo specimens figured in 
the Monograph appear to belie this statement. The specimen figured on PL X, 
fig. 4rt, shows no spine-pits on its infero-marginalia, but is figured as M. Farlcinsoni. 
I have isolated a dorsal ossicle, which shows the specimen undoubtedly to belong 
to M. Hucatus. The specimen figured on PI. XI, fig. 3 a, as M. iDicatits, shows 
spine-pits on its supero-marginalia in one inter-radius only. After very careful 
examination of this specimen, I have come to the conclusion that this inter-radius 
— the right-hand u]iper inter-radius of the figure — has been added by a dealer 
from a collection of ossicles of M. Fayliimoni to an imperfect specimen of M. Jiiicafiis. 



NOTES ON GENERA. 125 



deniis — Staueandekasteh,' uox imi. 

Pentaciokos (pars). V[>. 7t)-S'.t of this Mouograj)li. 

The species hitlbij'enis, Bui/sli, coroiudns, oci'llatitfi, hispiiiosiis, iiistilli/crns, and 
siiitninatiis (pp. 70 — 8'.* of this Monograph), which have been foriiierly phiced in the 
genus I'lmtaccros, together with the new species anjus (p. U9), shouhl, I think, 
now be ascribed to a new genus. The phites of these species are breast-phite- 
shaped, at times ahnost cross-shaped, and l)ear a characteristic type of oi nanient 
(see p. 113). In both these respects and in the absence of papidar areas the 
species differ widely from species of recent Pevtuceros, with which the only feature 
they have in common is the circlet of raised plates on the abactinal surface of the 
disc. 

The type species of the new genus is Stauramleraster Dotjsii, and its diagnostic 
characters are : 

Arms high, well produced, marginalia breast-plate-shaped, generally with a 
rabbet-edge free from ornament, and a raised interior area, either smooth or with 
ornament of an embossed type. A circlet of swollen plates present on the 
aljactinal surface of the disc. 

This genus, with tlie following genus, may l)e placed provisionally in the family 
Pentacerotidae. 



Genus — Hadkandebaster,- novum. 

Pentaci;i;os (par.s), p. 8G of this Monogi-aph. 

The species described as Pentaceros tibbreviatus on p. 80 of this Monograpii 
differs so considerably in the shape of its marginalia and their ornament from the 
species of Stauranderasler and recent species of L'cntacevos that I have placed it in 
a now genus. 

The type species is HaJraitdcnititer abbrvciatiis, and the diagnostic characters 
of the new genus are : 

Arms high, well produced, marginalia either hexagonal or rounded, very thick, 
ornament spread imiformly over the surface of the plate. Pedicellaria l>i-valvate. 

* aravpoi = a croas, Hvitipov = a raised garden border. 
' dSpot = stout, nfSrjijOf = a raised garden border. 

19 



126 FOSSIL ASTEROIDEA. 



GENERAL CHARACTERISTICS OF CRETACEOUS ASTEROIDEA AND 

OPHIUROIDEA. 

The luajurity of Cretaceous starfishes belong to the Phaiierozonate forms 
iucliided in the families Peutagouasteridaj aud Peutacerotida?. Modern forms of 
the genera of these families are widely distributed geographically, but, generally 
speaking, they are characteristic of warmer waters than those of the English 
Channel of to-day. 

The Chalk starfishes are specialised types which, although approximating to, 
are not identical with, modern genera. The differences, at any rate in some cases, 
appear to be distinctly pln'siologically advantageous. 

Mdopaster and Mitraster, the most abundant of all Chalk starfishes, possess 
not only a specialised type of ornament but also characteristic massive plates. 
The arms tend to become shortened and the disc correspondingly enlai'ged. 

The Chalk species of the Pentacerotidje differ from the modern forms, 
inasmuch as they are more strongly built ; the abactinal areas are not reticulate, 
and all species possess iuterniarginalia which cause the characteristically deep 
body of these forms. 

The Chalk is a deposit formed in seas which were sufficiently distant from land 
to avoid any great admixture of clay or sand. Globlgcrina and other forms of 
pelagic Foraminifera floated in abundance on the surface of the sea, which, because 
of its temperature, must have been exceedingly favourable to prolific forms. 
In the circumstances there must have been an abundance of food for starfishes, 
and Ave find, therefore, that the long-armed, comparatively' active Astropectinidaj, 
which were so characteristic of the Jurassic shallow water deposits, are displaced 
by more sedentary forms which tend to specialise, so as to obtain, bj* the enlarge- 
ment of the disc or development of intennarginalia, the largest possible space for 
their digestive organs. 

The irregular Echinoids which are so characteristic of the Cretaceous seas are 
similarly sedentary forms. 

The fossil Ophiuroidea also closely resemble modern forms. The isolated 
vertebral ossicles of 0. serrata, figured PI. XXVII, figs. 3 c, 3 (/, 3 e, cannot be 
distinguished from the ossicles of recent Ophiuroids. Complete specimens of 
Ophiuroidea aud Asteroidea are rare, but isolated plates are very numerous in 
the Upper Chalk. They are, on the contrary, rare in the Lower Chalk, 
according to experienced collectors, as, for example, Mr. Dibley. 

The following starfishes are found in the zones indicated. The List is compiled 



PHYLOaENY. 



127 



from the papers of Dr. Rowe (' Proc. Geol. Assoc.,' vols, xvi, xvii), and al.so 
from notes furnished hv Dr. II. I'. IMackniore and Mr. T. H. Withers. 





£ 
1 

tS3.= 


Zone of 

Belemnitella 

mucronata. 


Zone of 

Actinocamax 

quadratus. 


J 


Zone of 

Mtcraster 

cor-anginum. 


Zone of 
Jf. cortes- 
tudinarium. 


1. 
« 

■s 
as 

°i 

N a, 


■S.2 

§1 
IS.S 


Zone of 

Rhynchonella 

Cui'ieri. 


•SI 

1! 


i 

II 

•3? 
11 


i 

' Nymphaster Coomhei, Forlies 
— ol'Hjdpla^, Slailen 
Pentagonaster qiiinqiielotm, 

Goldfuss 
— obtugiig, Forl)es 
Metopaster Parkinsoni, Forbes 

— uncatug, Forlies . 

— quadratus, n. sp. 

— corn lit Hg, Slailen 
Miiraster Hunieri. Forbes 

— riigatiig, Forbes 
Pycinaster angugtatiig, Forlies 

— genonengis, Valette 
Siaiiranderaster hulbiferiig, Forbes 

— Boygi, Forbes 

— - ocellatug, Forbes . 

— pistiUiferug, Forbes 

— argug, n. sp. . 
Arthraster Dixoni, Forljes . 

„ crigtatus, n. sp. . 




X 

X 

X 
X 

... 
X 

X 
X 


X 
X 
X 

X 

X 
X 
X 
X 
X 
X 
X 


X 
X 

X 

X 
X 
X 

X 


X 

X 

X 
X 

X 
X 
X 

X 

X 
X 
X 


X 
X 

X 




X 


X 



THE PHYLOGENY OF THE CRETACEOUS ASTEROIDEA. 

If we examine the various species of a genus or group of related genera of 
Cretaceous Asteroids, we find that there is a similar transition from smooth to 
spinous forms tlirough an intermediate form, to that which has V)een ol)served in 
Ammonites and Brachiopods. 

Both in Ammonites and Brachiopods single specimens sliow the whole life- 
history of the individual, for the shell of the animal is luit materially altered in 
character after it has once been formed. It is therefore possible to show, f. f/., 
that the character of the ornament of the shell of an Ammonite was smooth 
in its infancy, costate in its adolescence, spinous in the adult, and it has also been 
shown that this life-history dei)icted by the individual is an ejiitome of the 
phylogenetic history of the species (Buckman, ' Mon. Amnion. Inf. Oolite,' Pal. 
Soc, 1905, p. cc). Similar ol)servations have been made with regard to Brachio- 
pods (B)ickman, ' Quart. Journ. Geol. Soc.,' vol. Ixiii, 1907, p. 338) ; primitively the 
Brachiopod .shell is smooth externally, more advanced forms ai-e j)rogi'essiveIy 
costate and then spinous. Occasionally species may regress towards a primitive 



128 



FOSSIL ASTEROIDEA. 



plain form througli a costate phase. The progression or elaboration is known as 
" anagenetic " development, and the retrogression as " catagenetic." 

It is regrettable that our present state of knowledge of Chalk Asteroids does 
not allow us to recognise such definite phylogenetic series as those obtainable in 
Brachiopods or Ammonites. The plates of an Asteroid are constantly being eaten 
away and replaced by new calcareous matter, so that the adult plate may differ 
considerably in character from its young phase. An opportunity for study, 
however, is afforded by the fact that all the plates are not formed at once. The 
more distal plates are younger than the proximal plates, and therefore resemble 
more closely those of the young form. The resemblance is not, however, 
quite exact, as they are formed later in the life of the individual, and may show 
consequently characters which have appeared later in the history of the species. 
Doubtless, if it were not for the paucity of the well-preserved specimens of 
Cretaceous Asteroids much might be still made out by a comparative study along 
these lines. 

The following paragraphs are only suggestions made in the hope that more 
material may come to light at a future date. The great majority of starfishes are 
and have been spinous forms, and I propose to assume that the original ancestor 
in each group was spinous. 



Genera — Metopaster and Mitraster. 



(rugose) 



Metopasters. 

M. nneatus 
(rugose) 



M. corniifiis 
(spinous, with rugosities) 



M. Pnrl-insoni 
(spinous) 



M. Hnnieri 

(spinous, with 

rugosities) 



MiTEASTEES. 

M. riigatKS 
(rugose) 



M. cnmpadus 
(smooth) 



Original spinous form. 

It is convenient in this gi'oup to consider the ornament on the raised central 
area of the marginalia. It will be seen from the above diagram that the spinous 



I'llYLOGENY. 129 

form, which was the ancestor of these two groups, early gave rise to two offshoots, 
one of which inchules the Metopaaier species, the other the Mitntnter species. 
Botli genera retained evidence of common ancestry by the possession of similar 
ornament of the specialised " pustulate " type, and by the similar appearance of 
their ultimate supero-marginalia, which, instead of being smaller than the rest of 
the superior marginal series, are as large or larger tliau tlu-sc .1/. r<rrnututt, which 
is the only species found in the lower zones of ilic chalk (Tuionian), shows that 
early specialisation set in. This form is spinous without rugosities when young 
(see p. 55, PI. XTV, fig. 5), l)ut older specimens (see PI. XX fX, fig. I'l) accpiire 
rugosities. 

The species of Mcfopaster, ]\f. (jiuuh-ofm^ and .1/. uncutiis, have lost all spines 
from the raised central area of their supero-marginalia, and, instead, possess 
rugosities. The raised central areas of the infero-marginalia possess neither 
spines nor rugosities, but are quite smooth. M. quadratua has also acquired, as 
a frequent variation, a primitive type of ultimate supero-marginalia (see p. 98). 
The tyjie of ornament shows the sjiecies to be highly specialisi'd, and this fact, 
tog-ether with its occurrence in the his-her zones of the Chalk, affords us an 
explanation of the remarkable peculiarity of the terminal supero-marginalia on 
the supposition that it is a catagenetic tendency. 

The species of Mif raster show even more deciilcil evitlenee of \hc three phases 
— spinous, rugose, smooth. These alterations oidy occur on the raised central area 
of the supero-marginalia. The infero-marginalia ai)peai- to pass directly from the 
spinous to the smooth stage without the intervention of a rugose stage. 



Genera — Calliderma, NYMruASTER, and Pentaoonaster. 

This group tends to become smootli bolli in the Sunonian and in the Turonian- 
Cenomanian. 

Turonian-Cenonianian forms include 6'. SinilJii.r, ('. Jul inn, .V. ('oomhii, N. 
oIiyoj)hi,r, and N. iiumjhmhix, wliich are spiiious; N. riKjomK, which is rugose; N. 
railiotitu, which is smooth on the oldei' proximal plates, but rugo.'^e on the younger 
distal plates. 

Senonian forms include /'. 7"///'//"7(;/«/ and /'. hiinifns, wliich are spinous; P. 
obfnsiis, which very often possesses marginalia which have lost the majority of the 
spines and are almost smooth. 



130 



FOSSIL ASTEROIDEA. 



Gen us — Staukanderaster. 



S. argtiK S. ocellattis 
(spinous) (spinous) 



S. sqvamatiis 
(smootli) 



8. jiisfiUiferus 
(smooth) 



S. coroimfuA 
(smootli) 



8. Boysii 
(spinous) 



8. bipiiiictafus 8. liilhiferus 
(spinous) (spinous) 



Original spinous form. 



The left-hand stem and branches of the diagram above are occupied by the 
generalised species which have long tapering arms. They show the transition 
from spinons to smooth forms. The spinous form of these species is 8. Boi/sii. 
In the lower zones of the Chalk one species {S. coronatus) appears. This has 
neither spines nor rugosities on the majority of its marginalia, although a few 
distal marginalia are rugose. N. squamatus, which is almost identical in character 
with 8. coronatus, except that it is of smaller size, and 8. jnstiUiferus (arms not 
known) are the smooth forms which characterise the upper or middle zones of 
the Chalk. 

The right-hand stem and branches are occupied by various specialised forms 
from the upper and middle zones of the Chalk. »S'. hnibiferus shows a specialisa- 
tion in the l)idbiform character of the extremity of its arms, and 8. hipunctaius in 
the character of the spines on the ventro-lateralia. 8. ocdlatns and »S'. argus are 
specialised in the peculiar nature of their armature. All these forms are spinous, 
their specialisation lying in other directions. 

Genns — Hadranderaster. 



The majority of the plates on this form are spinous, although a few distal 
plates ai'e smooth, probably indicating a catagenetic tendency in this direction. 



CJJ.US.SAllV. 131 

Genus — i' vi i nastkk. 

Spines are very feebly developed in this genn.s. 'I'lie spine-pits when present 
are very shallow, and often they are absent altogether. Spine-pits are often 
visible on the actinal plates after they have disappeared from the abactinal series. 

r. crassim possesses rugosities on the distal marginalia. 

Genus — Authuastkr. 

A. crisfata.'i possesses botli spines and rugosities; A. iJ'woui is rugose without 
spines. 

Speculation as to phylogeiiy in these latter three genera, in view of the state 
of our knowledge, would Ije valueless. 



GLOSSARY. 

The following glossary and diagram (Text-fig. o I) is aihled to aid the geologist 
who has l)ut little acquaintance witli modern zoological terms. 

Abactinal. — Applied to the surface which is uppermost when the starfish walks 
on its tube feet; the term " dorsal" is used by some authors in the same sense. 

Actinal. — Applied to the surface which is undermost when the starfish walks. 
On this surface are situated the mouth and the andiulacral grooves. The term is 
used synonymously with " ventral " by some authors. 

Afhimbulacralia or Adambulacral Plates. — The ossicles which are adjacent to the 
andndacral ossicles. In the order " Phanerozo)iia," to which the great majority of 
Chalk Asteroids belong, these ossicles are visii)le on the actinal surface, bordering 
the aml>ulacral groove and hiding tlie ambulacral ossicles. Adandjulacralia may 
be recognised by their prominent armature of spines. 

Adnulialia. — Ossicles situated on either side of the radialia (</. v.). 

Ambulacral. — The ambulacral groove is the groove stretching from the mouth 
to the extremities of the arm. It is formed by the ambulacral ossicles, which meet 
in the middle so as to form an arch. The tube feet project through the arch and 
into the groove. 



132 



FOSSIL ASTBROIDEA. 



Gentrale. — The most central ossicle on the abactinal surface of the disc. 
This ossicle, together with five ossicles situated inter-radially and called the 
" Primary Inter-radialia," are especially prominent in the young form, in which 
they often occupy almost the whole of the aljactinal surface. Generally speaking 



/ r)e of ti)e five 
^^ (.primary I i-jter radialia 



„-Centra.Le 




"RadlaCiLOL 



QclraaicLU< 



S uperomarairja-Lia 



Text-hq. 'il. — Abactiniil view of a specimen of Stauramhrasli^r liilhiferus, natural size, slightly restored from 
the specmien from Charlton, Kent, registered E. 4314 in the British Museum (Nat. Hist.). 

they can be distinguished in the adult form by their larger size, and occasionally 
they are especially prominent, as in species of Stauranderaster (Text-fig. 34) and 
of the recent genus Pentaceron. 



Marginalia. — In adult forms of the order " Phauerozonia," which includes 



Ipalxontoovnpbical Socict\^, 1008. 



A MONOGRAni 



r> u I r I s II F o s s T L 



ECHINODERMATA 



FROM 



THE cnKTArEOCS FORMATIONS. 



VOLUME SECOND. 
THE ASTEEOIDEA AN]) OPHIUEOIDEA. 



W. K. S PENCE K, B.A., F.(..S. 



PART FIFTH. 
Paqes 133 — 138; TiTLE-PAOE AND Index. 



LONDON: 
PRINTED FOli THE PAL^ONTOGRArHICAL SOCIETY. 

1908. 



rillNTEl) BY ADLARD AND SON, LONDON AND DOKKING. 



ADDENDA ET CORRIGENDA. 133 

almost all Cretaceous Asteroids, and in (|uitc young forms of the order " Crypto- 
zonia," the margin of the disc and arms is l)ordered by specially prominent ])lates 
— the " Marginalia." The abactinal series are called " Su[)ero-marginalia," ami the 
actinal series the " Infero-marginalia." 

Prirmirij Inlcr-md'udvi. — See Ceiitrah'. 

liadiuliti. — The abactinal series of plates along a uiajnr radius are called the 
radialia. 

Rddins. — A line drawn from the central point of the disc to an extremity of 
the arm is called the " Majur railing," R. A line drawn from the central point of 
the disc to a point half-way between two radii is called the " Minor radius" r. 
This is sometimes called an " Ihter-radins." 

Spiiie-pils. — Depressions in a plate for the articulation of spines (see p. 113). 

Ventro-1 ate r alia . — The plates on the actinal surfaL'c uf the Asteroid excluding 
the infero-marginalia and the adanil)iilacralia. In lln' inter-radial regions these 
plates are often rliomboidal. A typical view of an isulateil plate of this descrip- 
tion is given (PI. XXIN, tig. I). 



ADDENDA ET COmUOENDA. 

Page 24, line 19, for Schiihe read G. F. Schulze. 

Rage 2G, Localitij, etc., for Upper White Chalk near Norwich read llnni Clinlk, 
Wed Norfolk, the precise localitij unknown. 

Page G7, line 11, for Goniaster compactus read Gouiaster (Goniodiscns) coiiipactii.-<, 
and omit all reference to Forbes, 18-i8. 

Page G9, line 15, for Stellaster comptoni read Gouiaster {Stella. '<ter) Comptoui. 

Page 71, line -i, for Stellaister eleyaiis read Goniaster (Stellaster) cleijans. 

Page 89, line 8 from end, for Bourijiietiicrinns read UoHnjucticrinus. 

Page 90, last line, for Upper Greensand read Lower Chalk. 

Page 95, line ^{, for Sladen read Forbes. 

Page 95, line 1:3, for (p. 8,9) read (/;. 89, PL XAF, .//.'/• ^)- 

Page 101, line 9 from end, the first reference should read Oniii i;.\, I.innarrk, 
ISOl. Sijsteme des Animaiuv sans Vertebres, p. 350. Tlic date of the reference 
given is 181f). 

Page 102, line 12, for iSil read tSIO. 

20 



134 FOSSIL ASTEROIDKA. 

Page lOo, line ]0, add rur-ainjnlinun zom', Nnrflijli'cl, Kent, mul llhiinlfunl, 
Dorset. 

Pag'c lOo, line 11, add in synonym: Uriiiui;A .skkkata ? Furbcs, 18-to. Pruc. 
(i)'ul. (Soc, nil. Ir, J)- 2'34<. 

Page lOo, line 4 from end, fov paffiseiitnni read piirrlscidis. 

Page lOi;, line 7, after E5060 add and E5061 ; under Lnrnlifi/ insert I'^U.-csIduc. 

Page 117, line 12 from end, for M. read Mdajxislcr. 

Page 117, line 7 from end, for M. read Mil ra sin: 

Viigc 117, line 2 from end, for M. read Mcliqxislrr. 

Page 118, line o from top, for M. read Mltni.^ln: 

Page I is, line 7 from top, for l\l. read Mflupuslrr. 

Page lis, line i» from toi), for M. read Melopaslrr. 

Page 118, line 12 from top, for 31. read Mit raster. 

Page 119, line 3 from end, for hipunctatas read hupiuums. 

Page 120, line 13 from end, for hlpiuictatus read hispinosus. 

Page 130, table and line 7 from end, for hipanctahiH read hi>ipiiiosus. 

Page 121, lines 2, 4, 0, for ^S'. read Slannnulcraslrr. 

PI. IV, figs. 2 — 4, for Lun-cr read Vppvr. 

PI. V, fig. 1, for Tdiiildaslcr sulcalns read I'fil/idcrmn i<iitithi;v (see \>. 123). 

PI. VII, figs. In and 2 (^ for ? N [imphaatrr CikhnIiu read CaUhh-nna SiiiiUiLr 
(see p. 122). 

PI. X, fig. 4, for Melupader Farlclnsord read Mclupa-slcr niicatas (see p. 124). 

PI. XIX, fig. 3, for Ni/mphnster Goombli read Gallidcrma Siitifhiai (see p. 122). 

PL XXI, fig. 2, for Pi'iitaijuiuister rulnialus read ?a ijuamj farm of Pijcinaster 
aiKjndaiit.s (see jd. 95). 

PI. XXIV, fig. 1, for rf'idarcro!^ ahhrevhitiis read TTadraiidf ranter alibrerialus 
(see p. 12-3). 

PI. XXV, fig. 2, for Upjjer Greensand read Luirer Gkallr.^ 

PI. XXV, fig. 6, for Genns? sp. ? (p. 93) read ? StMuranderaslrr anjes (p. 99). 

PI. XXV, fig. 7, for Feidaceros ? ii. f>p. (p. 89) read rijcinasler a injnatatii.^ 
(pp. 89, 95). 

PI. XXV, fig. 8, for manjinal read internal. 

PI. XXVI, fig. l,for Peidaeeros punctattiff read Pi/euiaster seiionensis (see p. 95). 

PI. XXVIj fig. 4, for Galliderma mosaicinit read Pycinafitrr (nn/nslalit.s (see 
p. 95). 

PI. XXVI, fig. 4, for Fraui the Lower Ghall: read From the Upper Chalk. 

PI. XXVir, fig. oh, for ahael'inid read acttual or adural. 

PI. XXVII, fig. 3 r, for .svW^' read right side. 

' Mr. H. Woods iiifonus mo Oat recently he lias been alilo to mateli the iiiafri\ in wiiieh lliis 
I'ojsil is embedded. 



ADUK.NDA ET CURRIGEMJA. 1;}5 

IM. X.WII for Ojiliinra pavuL^entitm read Oiihiid-n j)an}is('iili,-<. 

I'l. X.Wll, fig. -I; before unlnral x/vt' insert slujhtli/ less thun. 

I'l. XXIX, fig. 12, for Sl,i,Ini sp. reiul Sl'i<h;n. 

Oil all IMivtos (except XXVI) for (Jallideriita musau-niu read ('. Sniilhix (see 

On all Plates for Mclopastcr lluwerbanLii, M. Mantclli, M. zonatus, read M. 
I'll rkuiso III (see p. 121). 

On all I'lates for Metu^jastcr cimjnlattis read .1/". inicatits (see p. 121). 

On all Plates for PriUaceros bidhifcrus, J'. Jlui/sii, P. coronalus, 1'. hipiiudatiis, 
/'. siiKamatns, 1\ iiistilUfenis, P. occllntus, P. anjns, read corn'spomliiifj sjicclcs of 
Staitninilcriisfcr (see p. 12r)). 

On all Plates for PcntiKjunastcr mii(jalvplax, read P. nuiinini'lubd (see p. 108). 



INDEX 





PAGE 








PAGE 


Abactiual 


131 


Calliderma 




4, 122, 129 


Acalia ..." 


100 


— 


latuui 


12, 


116 ; ii, iii 


Actiual 


131 


- 


niosaicuiii 


9, 123 ; V, vi, vii 


Adambiilaeral plates . . 


131 


— 


Suiithia; . .6 


115, 


123 ; i, viii 


Adraclialia 


131 


Ceiitrale 






... 132 


Ambulacral ... 


131 


Coelaster Couloui 




... 109 


Ampliiura 


106 


Coinptonia 




... 69 


— cretacea 


107; xxviii 


— 


comptoni 


69 


; xvii, xviii 


Ampliiuritla! . . 


106 


— 


elegans 




71 ; xvii 


Ai-thraster 


91,131 


Cryptozouia ... 




... 100 


— cristatus ... 


93, 118 ; xxix 


Cupulaster pauper ... 




... 109 


— Dixoni ... 


. 91,118; xviii, xxix 










— senoueusis 


93 


DoriguUii 






... 69 


Asterias Dunkeri 


109 










— jiireusis 


108 

25 


Euasteroidea ... 




3 


— lunatus 










— quinqueloba 


107 










— Scluilzii 


109 


General characteristics 




... 126 


— tabulata 


108 


Generic and specific characters 




... 112 


Astrogoniuin 


24 


Glossary 






... 131 


— august atu 111 


22 


Goniaster 






24, 76 


-- Bowerbaukll 


42 


— 


augustatus 




... 21 


Coombii 


15 


— 


Bowerbankii 




... 42 


— coinpactuin 


67 


— 


compactus 




... 67 


— Himtcri 


59 


— 


Coombii ... 




... 15 


— latum . . . 


12 


— 


Hunteri . . ... ' 




... 59 


— lunatuui 


27 


— 


latus 




... 12 


— Mautelli 


38 


— 


luuatus 




... 27 


— mosaicum 


9 


— 


iiiauiuiiUata 




. . 110 


— Parkiiisoui 


32 


— 


Mautelli 




.. 38 


— reetiliueuiii 


32 


— 


margiuatus 




... 110 


— rugatuni 


63 


— 


mosaicus ... 




9 


— Smitliii 


6 


— 


Parkinsoni 




... 32 


subluuatvuu 


51 


— 


rectilineus 




... 32 


— imcatuin 


47 


— 


regularis ... 




... 59 


Astropeeteii ... 


90 


— 


rugatus 




... 63 


Astropcctiuidx' 


90 


~ 


semilunata 




... 38 



TXDEX. 



Goniast<>r Smitliii 

— sul>luuatus 

— iincatiis 
Goniotliscus ... 

P)Ower1)aiikii 

— TTunteri 

— Parkiusuiii 

— rectiliucu.s 

— rii^tus . . . 

— sublunafiis 

— iincat\is... 



Harli-aufleraster 

Hosia 

Key-tal)Io 

Liiic-kia 
Linckiitlnp 

Martfinalia 
Mctopastor 



alilireviatus. 



PAOE 

C) 

... 51 

. . 47 

■2i 

... 42 

. . 59 

38 

32 

32 

G3 

51 

47 

1-25, 130 

111. 118,125 

24 



Mitraster 



Bowerbantii 

cingulatus 
Cdrniitiis ... 
Mantolli ... 
Parkiusoni ol 

ijuuilratns 
sublunatiis 
lineal us . 
zoiiatns 

coinpactus ... 

Huuteri 

ru<'atus 



Ncotopliiurrp . . 
Nympliastor ... 

■ — Coombii 

— marginatus 

— oligoplax 

— r.idiatus 
nigosus 



114 

100 

loo 

132 

30,97,124,128 

... 42 ; XV, xvi 

53; xiv 

55,117; xiv 

38; xiii 

Ilk 117, 124; ix-xii, 
xvi 

97,118 

51 

47, lis ; xi, xiv, XV 

45 ; xii 

57, 128 

... G7, 118 ; xvii, xxvi 

... 59, 117 ; ix, xii, xv 

G3, 118; xvi 

lor, 

...14, 73, 94, 122, 129 
. . 15,113; vii, viii 

18, IK); viii 

... 19, 114, IKJ; viii 

73,117; XXV 

9|., 117; xxix 



Ogiuastor 

Opliidiastor 

Oplii<i;_'lvi>lia 

bridge reusis 

toxaiia ... 
Ophiolopiiliila! 
Opliiolepis 
Opliiot.itauos . , 

— - lajvis 

— inagiius 

— tenuis ... 
Opliiura 

Fiteliii 
— ■ granulosa ... 

— parviscntuiii 
- — pulcluMiinia 

— si'rrata 
Opliiuri>i(l«>a . . 
Oreaster 

— ■ Boysii 

— bulbiferus ... 

— coronatus 
ocollatus 

— obtusus 

— pistilliformis 

— jiislillifcrus .. 
Ornaiiu'iit 

Pedicellariii,' ... 
Pentaceros 

— abbreviatus 

— bispiuosus 

— Boysii ... 80,12. 

— bulbiferus 77, 

— coronatus 82, 1 

— dilatatus . 

— ocellatus ... 

— pistilliferus 

— puuctatus 

— senoueusis 

— squamatus 
Peutacerot id.T 
P»'ut;ig< master 

— lunatus 

— megaloplax 

— obtusus 

— (juinquoldba . . 



PAilK 

r;9 

lull 
lol 
IM 
111 

iMl 

I>>1 

. l(l|. 

... lO.'i ; XXviii 

1(M( ; xxviii, xvix 

li'l: xxviii 

... lul 

ln:l; xxvii 

III 

lo:; ; xxvii 

.. 112 

ln-2; xxvii 

101 

7G 

80 

77 

82 

85 

71- 

88 

88 

11;: 

114 

... 76 

80, 125 ; xxiv 

87, 125 ; xxiii 

5 ; xxii, xxiii, xxvi 

125 ; XX, xxi, xxiii 

25 ; xix, xxiv, xxv 

110 

85, 125 ; xxv 

88. 125 ; xxv 

...88,95; xxvi 

81,95 

83, 125 ; xxv 

7i;, 99 

24, 73, 122. 129 

. 25, IIG; iv 

... 27, 108; iv 

74, 115; xxii 

108, 11 I. III-. 

21 



1:1S 






INDEX. 










PAGE 






PAGE 


Pentagonaster rectilineiis . . . 




... 32 


Stauranderaster bipvmctatuf 


(=bispinosus) 119 


— regularis 






... 31 


bispiuosus 




... 125 


— robustus 






73; xxi 


— Boysii 




120, 125 


— semihmatus 






... 38 


— bulbiferus 


113,119,120 


121,125 


PentagouasteridoB 






. . 3,94 


— coronatus 


114, 


120, 125 


Peut.agonasteriufc 






4 


— ocellatus 




121, 125 


Phanerozonia 






3 


— pistilliferus 




120, 125 


Pli_vl<>geu_v 






.. 127 


— si|uaniatus 




120, 125 


Primary- inter-radialia 






. . 133 


Stellaster 




09 


Pycinaster 






95, 131 


— albensis 




... 112 


— angustatus 93, 95, 


119; ix 


, xxi, XXV, 


— Comptoni 




... 69 






xxvi 


— Coombii . . 




.. 112 


— senonciisis 95, 114, 119 ; 


xxvi, xxix 


— elegans . . 




71 


Pyenaster 




21, 95 


— Sclmlzii 




109 


— angustatus 21, 95 


ix, xxi. 


XXV, xxvi 








— prassus 


96, 


119 ; xxix 


Tomidaster sukatus ... 




. . 123 


Radialia 

Radius ... 




... 133 
... 183 


Tosia 

— lunata ... 

— regularis 




... 24 
... 25 
... 31 


Specific and generic characters 
Spine-pits 




112 
... 133 


Ventro-lateralia 




... 133 


Stauranderaster 


.99 


, 125, 130 








— argus 




99; 


XXV, xxix 


Zygophiuras ... 




. . 101 



.ADI.AUn AND SON, IMI'Ii., I.nNlON AND DORKINO. 



PLATE I. 
Calliderma Smithi^, Forbes, sp. (P. 6.) 

From the Loiver Chalk. 

Fis. 

la. Actinal aspect; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 

c. Infero-marginal plates ; magnified 2 diameters . 

d. Lateral view of the marginal plates ; magnified. 

e. Adambulacral plates ; magnified. 

/. Actinal intermediate plates ; magnified 3 diameters. 



CI I 





Ailbedrle ielel lilli 



PLATE II. 

Callidebma latum, Forbes, sp. (P. 12.) 

From the Lotver Chalk. 

Fig. 

1 a. Actinal aspect ; natural size. (Coll. Brit. Mus.) 

b. Infero-marginal plates ; magnified 2 diameters. 

c. Actinal intermediate plates ; magnified 3 diameters. 

d. Adambulacral plates ; magnified. 

e. A moutli-plate ; magnified. 

a. Actinal aspect of another example, with a portion of the actinal floor removed, 

showing the stellate bases of the abactinal plates or paxillse ; natural size. 
(Coll. Brit. Mus.) 

b. Actinal surface of part of the ray ; magnified 1^ diameters. 

c. Infero-marginal plates ; magnified 3 diameters. 

d. Stellate bases of the abactinal plates or paxillee; magnified 4 diameters. 



PI 




)J 






2- j! 3*^^* 



Ma 




¥-^ 

> 



^r.aear> ielet lich 



Il&nharl imp 



PLATE III. 

Calliderma latum, Forbes, sp. (P. 12.) 

From the Lower Chalk. 
Fig. 

1 a. Actinal aspect of an example from Amberley ; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 

c. Lateral surfaces of the marginal plates ; magnified. 

d. An infero-marginal plate ; magnified. 

e. An actinal intermediate plate ; magnified. 

2 a. Actinal aspect of an example from the Chalk Marl of Dover ; natural size. 

(Coll. Brit. Mus.) 
b. An adambulacral plate ; magnified . 

3 a. Actinal aspect of an example from Washington, with a portion of the 

actinal floor removed, showing the stellate bases of the abactinal plates or 
paxillffi; natural size. (Coll. Brit. Mus.) 
b. Stellate bases of the abactinal plates or jiaxillge ; magnified. 



3b 



V 







mdj 







A-4Sadiledelrthth 



Hanlurt irnf 



PLATE IV. 

Pentagonaster lunatus, Woodward, sp. (P. 25.) 
From the Upper Chalk. 

FlQ. 

1 a. Actinal aspect of the type specimen ; natural size. (Coll. Norfolk and 

Norwich Mus.) 
h. An actinal intermediate plate ; magnified. 
c. An infero-marginal plate ; magnified. 

Pentagonaster megaloplax, Sladen. (P. 27.) 
Frovi the Loiver Chalk. 

2 a. Actinal aspect of the example figured by Forbes, under the name of Cmdaster 

(Astrogonium) lunatus ; natural size. (Coll. Brit. Mus.) 
/;. An infero-marginal plate; magnified 3 diameters. 
c. Lateral view of the margin ; natural size, 

3 a. Actinal aspect of another example ; natural size. (Coll. Brit. Mus.) 

b. An actinal intermediate plate ; magnified 6 diameters. 

c. Adambulacral plates ; magnified 6 diameters. 

4 a. Actinal aspect of an example from the Upper Chalk of Bromley ; natural 

size. (Coll. Brit. Mus.) 
h. Lateral view of the margin ; natural size. 
r. Lateral surface of an infero-marginal plate; magnified. 

d. An infero-marginal plate ; magnified. 

e. An actinal intermediate plate ; magnified 6 diameters. 



PI IV 



lb. 




AHSearledelctliLh^ 



Hanhart mip 



PLATE V. 

ToMiDASTEE SULCATUS, Sladen. 

From the Qreij Chalk. 

Fig. 

1 a. Actinal aspect ; natural size. (Coll. Brit. Mus.) 

b. Actinal intermediate plates ; magnified. 

c. Adambulacral plates; magnified 3 diameters. 



Callideema mosaicum, Forbes, sp. (P. 9.) 
From the Lower Chalk. 

2 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 

c. Abactinal plates ; magnified. 

d. Supero-marginal plates ; magnified. 

e. Madreporiform body and surrounding plates ; magnified. 



I'l \ 



>^ 



s 



j>y 



lb 



1.1 







< 1 



>4 



'-:0m 



\%. 



^o 








AHSrarledelcLlith 



Hanharc imp 



PLATE VI. 
Callidebma mosaicum, Forbes, sp. (P. 9.) 

From the Grey Chalk. 

Fia. 

1. Abactinal aspect of an example from which the abactinal plates have been 

removed ; natural size. (Coll. Brit. Mus.) 
2 a. Abactinal aspect of another example from which the abactinal plates have 
been removed, showing the inner surface of some of the actinal intermediate 
plates and adambulacral plates ; natural size. (Coll. Brit. Mus.) 
/). Adambulacral plates, seen from within ; magnified, 
c. Actinal intermediate plates, inner surface ; magnified. 



HI VI 






ry:0 



AK Searli! ilsl et htK 



l!.i„K- 



PLATE VII. 

(?) Nymphasteb Coombii, Forbes, sp. (P. 15.) 

From, the Lower Gliallc. 
Fig. 

1 a. Actinal aspect ; natural size. (Coll. Brit. Mus.) 
h. Lateral view of the margin ; natural size. 

c. Adambulacral plates ; magnified. 

d. An infero-marginal plate ; magnified. 

e. Actinal intermediate plates ; magnified. 

2 a. Abactinal aspect of an example from the Grey Chalk at Folkestone ; natural 

size. (Coll. Brit. Mus.) 
h. A supero-marginal plate ; magnified. 

3 a. Abactinal aspect of an example from the Lower Chalk of Glynde ; natural 

size. (Coll. Brit. Mus.) 
h. A supero-marginal plate ; magnified. 



Callidkbma mosaicum, Forbes, sp. (P. 9.) 

From the Lotoer Chalk. 

4 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 
h. Lateral view of the margin ; natural size. 
c. A supero-marginal plate ; magnified. 



r-i vii 









m 






AHSearle d«l et kth 



Hanhftri imp. 



PLATE VIII. 

Nymphaster Coombii, Forbes, sp. (P. 15.) 

From the Lower Chalk. 
Fio. 

1 a. Actinal aspect of the type specimen ; natural size. (Coll. Brit. Mus.) 
b. An infero-marginal plate ; magnified 3 diameters. 

Calliderma Smithi^s, Forbes, sp. (P. 6.) 
From the Loiver Chalk. 

2 a. Profile view of a fragment of a ray ; natural size. (Coll. Brit. Mus.) 

b. Actinal view of the same; natural size. 

c. An adambulacral plate; magnified 6 diameters. 

Ntmphastbr oligoplax, Sladeu. (P. 19.) 
From the Upper Chalk. 

3 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 
b. A supero-marginal plate ; magnified. 

Ntmphaster maeginatus, Sladeu. (P. 18.) 
From the Upper Chalk. 

4 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 
b. A supero-marginal plate ; magnified 4 diameters. 



2c.. 




PI VI 



["■■'■■ 





^" 








AllGeurl^ (lelrthth 



Honhart imp 



PLATE IX. 

PiCNASTEE ANGUSTATUS, Fovhes, sp. (Page 21.) 

From the Upj^er Chalk. 
Fia. 
la. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 

Metopaster Parkinsoni, Forhea, sp. (Page 31.) 

From the Ujyper Chalk. 

2a. Actinal aspect; natural size. (Coll. Brit. Mus.) 
h. Lateral view of the margin ; natural size. 

c. An infero-marginal plate ; magnified. 



Mitrastee HuNTERi, Fovbes, sp. (Page 59.) 

From the Upper Chalk. 

3 a. Abactinal aspect of a small example with four supero-marginal plates ; 
natural size. (Coll. Brit. Mus.) 
h. Actinal aspect of the same ; natural size. 

c. Lateral view of the margin ; natural size. 

d. A supero-marginal plate ; magnified. 

e. An infero-marginal plate ; magnified. 



I\ 






"-? 




lb 




>». 



'^ 





H SmHc cwl^ lilK . 



Hanliart iino 



PLATE X. 

Metopastek Paekinsoni, Forbes, sp. (Page 31.) 

From the Upper Chalk. 
Pig. 
1. Abactinal aspect; natural size. (Coll. Brit. Mus.) 

2 a. Abactinal aspect of another example; natural size. (Coll. Brit. Mus.) 

b. A supero-marginal plate ; magnified 3 diameters. 

c. The madreporiform body ; magnified. 

d. An abactinal intermediate plate, with pedicellarian apparatus ; magnified. 

3 a. Actinal aspect of another example; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 
0. Adambulacral plates ; magnified. 

4a. Actinal aspect of another example; natural size. (Coll. Brit. Mus.) 
h. An inf'ero-marginal plate ; magnified. 

c. An actinal intermediate plate ; magnified. 

5 a. Abactinal aspect of a young (?) example ; natural size. 

b. A supero-marginal plate of the same ; magnified 4 diameters. 

c. Abactinal intermediate plates ; magnified. 



Pl.X. 



3b. 




A K.SearU ileVeb litk 



:"i.\r.ririfC iMiir 



PLATE XL 

Metopasteu Parkinsoni, Forbes, sp. (Page 31.) 

From the Ujjper Chalk. 
Fig. 
Iff. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 

h. A supero-marginal plate ; magnified 3 diameters. 

r. The madreporiform body ; magnified G diameters. 
2 u. Abactinal aspect of another example ; natural size. (Coll. Brit. Mus.) 

h. A supero-marginal plate ; magnified. 

c. An abactinal intermediate plate ; magnified. 



Metopasteu uncatus, Forbes, sp. (Page 47.) 

From, the U])per Chalk. 

3 a. Actinal aspect of a specimen from which the whole actinal floor has been 
removed, showing the inner surface of the abactinal floor ; natural size. 
(Coll. Brit. Mus.) 
b. Abactinal intermediate plates, inner surface ; magnified. 



PI. XI 



Ib^ 








n- 



\^.:-, 



^ 'ifv-: 



lo. 





A.Hrx.'arle drf.ellith 



}l;,inhai't imp 



PLATE XII. 

Metopaster Parkinson!, Forbes, sp. (Page 31.) 

From the Upper GhalJc. 
Fig. 

1«. Abactiiaal aspect ; natural size. (Coll. Brit. Mus.) 
h. Lateral view of the margin ; natural size. 

c. A supero-marginal plate ; magnified. 

d. The madreporiform body ; magnified. 

e. Abactinal intermediate plates ; magnified. 

Metopaster zonatuj;, Sladen. (Page 45.) 

From the Tipper Ghall\ 

2 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 
h. Lateral view of tlie margin ; natural size. 
c. The madreporiform bod}^ ; magnified. 

MiTRASTER HuNTEKi, Fm'bes, sp. (Page 59.) 
From the Upper Chalk. 

3fl. Actinal aspect; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 

c. A supero-marginal plate ; magnified. 

d. An infero-marginal plate ; magnified. 

e. Actinal intermediate plates ; magnified. 

Callidekma mosaicum, Forbes, sp. (Page 9.) 
From the Lower Chalk. 

4 a. Actinal aspect ; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 

c. Mouth-plates ; magnified. 

d. An infero-marginal plate ; magnified. 




PI XII 



HSedrle jcl.et]ii;1l 



Hanhart imp. 



PLATE XIII. 

Pentagonastee megaloplaXj Sladen. (Page 27.) 

From the Upper Chalk. 
Fig. 

1 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 
h. A supero-marginal plate ; magnified 3 diameters. 



Metopaster Mantelli, Forhes, sp. (Page 38.) 
From the Tipper Ghalli. 

2 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 

h. A supero-marginal plate (much weathered) ; magnified 3 diameters. 

c. The madreporiform body and surrounding plates ; magnified. 

d. Abactinal intermediate plates ; magnified 6 diameters. 

3 a. Abactinal aspect of the example figured by Forbes ; natural size. (Coll. 

Brit. Mus.) 
h. A supero-marginal plate ; magnified 3 diameters. 

4 a. Actinal aspect of another example figured by Forbes ; natural size. (Coll. 

Brit. Mus.) 
h. An infero-marginal plate ; magnified 3 diameters. 



Pl.XIH 



Ico. 



Zc-. 





Sol/. 





Zou. 




Zob. 







^CC. 




AHSearle del et liA 



Hanhart imp 



PLATE XIV. 

Metopaster uncatds, Forbes, sp. (Page 47.) 

From the Upper ChalJc. 

Fig. 

1 a. Abactinal aspect; natural size. (Coll. Brit. Mus.). 

b. An ultimate paired supero-marginal plate ; magnified. 

2 a. Abactinal aspect of another example ; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 

c. A supero-marginal plate ; magnified. 

d. The madreporiform body ; magnified 4 diameters. 

3. Actinal aspect ; copied from the figure given by Forbes in Dixon's ' Geology 
of Sussex ' (pi. xxi, fig. 5). 



Metopaster cingulatus, Sladen. (Page 53.) 
From the Upper Challc. 

4 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 

b. Lateral view of the margin ; natural size. 

c. A supero-marginal plate ; magnified. 

d. An abactinal intermediate plate ; magnified. 

Metopaster cornutus, Sladen. (Page 55.) 

5 a. Abactinal aspect ; natural size. 

b. Lateral view of the margin ; natural size. 

c. An ultimate paired supero-marginal plate seen from above ; magnified. 

d. The same seen in profile (lateral view) ; magnified. 



PI. XIV. 



Za/ 






Za. 



k r 




^.^...^- 






Scv. 





•f-a/. 







<d. 




lb. 




A,H Searle del ebJilh 



Hinharl irar- 



PLATE XV. 
Metopaster ungates, Forbes, sp. (Page 47.) 



Fig. 



1 a. Actinal aspect ; natural size. (Coll. Wright.) 
b. Lateral view of the margin ; natural size. 



Metopaster Bowerbankii, Forbes, sp. (Page 42.) 
jProm the Upper Chalk. 

2 a. Actinal aspect ; natural size. (Coll. Geol. Survey.) 

b. Lateral view of the margin ; natural size. 

c. An infero-marginal plate (weathered) ; magnified. 

d. Mouth-plates ; magnified. 

Mitraster Hunteri, Forbes, sp. (Page 59.) 
From the Upper Chalk. 

3 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 
b. A supero-marginal plate ; magnified 3 diameters. 

4 a. Actinal aspect of another example ; natural size. (Coll. Brit. Mus.) 

b. An infero-marginal j^late ; magnified 3 diameters. 

c. E.xtremity of the radial region ; magnified 3 diameters. 

d. Abactinal intermediate plates, seen from within ; magnified 6 diameters. 

5 a. Actinal aspect of another example ; natural size. (Coll. Brit. Mus.) 
b. An infero-marginal plate ; magnified 3 diameters. 



P] XV. 








4h. 



6 a,. 





a 




AHSearledeLetlilh. 




^<x 



^1^ 




2a 





Zb. 




r w^^'^' 



Hsiihart imp. 



PLATE XVI. 
Metopasteb Boweebankii, Forbes, sp. (Page 42.) 

From the Upper {?) Chalk. 

Fig. 

1 a. Abactinal aspect of the example figured by Forbes , natural size. (Coll. 
Brit. Mus.) 

h. Lateral view of the margin ; natural size. 

c. Tbe last three supero-marginal plates ; magnified 2 diameters. 

cl. Abactinal intermediate plates ; magnified 6 diameters. 



Metopastee Parkinsoni, Fortes, sp. (Page 31.) 

From the Upper Chall\ 

2 ft. A pair of ultimate supero-marginal plates and the odd terminal or " ocular" 
plate ; magnified 2 diameters. (Coll. Brit. Mus.) 
h. Lateral or marginal view of the same ; magnified 2 diameters. 

MiTRASTER EUGATUS, Forbss, sp. (Page 63.) 

From the Upper Challc. 

3 a. Abactinal aspect ; natural size. (Coll. Brit. Mus.) 

h. A supero-marginal plate ; magnified 3 diameters. 
4. Supero-marginal plates of another example ; magnified 2 diameters. (Coll. 

Brit. Mus.) 
5 a. Abactinal aspect of the example figured by Forbes ; natural size. (Coll. 
Brit. Mus.) 
h. Lateral view of the margin ; natural size, 
c. A supero-marginal plate ; magnified 3 diameters. 

(1. Profile or sectional view of the margin, showing a supero-marginal and an 
infero -marginal plate ; magnified 3 diameters. 



Say 



PI . XV] 



Sh. 





Zau. 




6oO. 




3cu., 





Zh. 



--t 






3b. 




lb. 



:''■ 




wt 



Icb 



Vt: 



V 





•'' :f ■V^'-' 



AH Searle olel et lith 



HanKart imp 



PLATE XVII. 

Metopaster Mantellt, Forbes, sp. (Page 38.) 

From the Upper CI alii. 

Fig. 

1. Actiual aspect ; natural size. (Coll. Brit. Miis., ^04-02.) 
a. Infero-marginal plate ; magnified 4 diameters. 

MiTRASTER coMPACTus, Furhps, sp. (Page ^7.) 
From the Upper Challi. 

2. Actinal aspect ; copied from Forbes in Dixon's ' Geology of Sussex,' pi. xxii, 

fig. 3. 

CoMPTONiA CoMPTONi, Forbes, sp. (Page 69.) 
From the Upper Greensaiui. 

3. Actinal aspect ; natural size. (Coll. Brit. Mus., 3-i31 1 .) 
a. Infero-marginal plate ; magnified 3 diameters. 

h. Lateral view of interbrachial arc ; natural size. 

CoMPTONiA elegans, Graij. (Page "].) 
From the Upper Greensand. 

4. Abactinal view ; natural size. (Coll. Brit. ]\Ius., E. 2567.) 
a. Actinal view of same specimen; natural size. 



PL.XVII 



la- 






r?> 



4a 






3a. 





A.H-Soeu-le oleletJifh. 



34 



?5f;.»1^ ') 



mnnm^ 



CRETACEOUS ASTEROIDEA 



Pitcher L^ imp. 



PLATE XVIII. 

Artheaster Dixoni, Forht'ft. (Page 91.) 

From the Lower CJialk. 
Fig. 

1. Actinal aspect ; natural size. (Coll. Brit. Mus., 47000.) 
a. Supero-marginal plate ; magnified 3 diameters. 



CoMPTONiA CoMPTONij Fovhc's, sp. (Page 69.) 

From the Upper Greensand. 

2. Abactinal view ; natural size. (Coll. Nortliampton Mus.) 
a. Isolated plate of interradial portion of disc ; magnified 6 diameters. 
h. Isolated radial ; magnified G diameters. 

c. Lateral view of interbrachial arc ; natural size. 

d. Supero-marginal plate ; magnified 3 diameters. 



PL xvm 






]a 



''>:k 





2d. 




2a 



mm 




1(1 



2h 



,i:ms 



AHSearleoleletkk 



2c 



•"^^■^?^?SSSx^^«*' 



CRETACEOUS ASTEROIDEA 



Pitcher LH imp. 



PLATE XIX. 

Pentaceros coronattjs, Forhpii, sp. (Page 82). 

From ilie Lower GJinlh. 

Pig. 

1. Abactinal aspect ; natural size. (Coll. Brit. Mus., B. 2562.) 
a. Lateral view of arm ; natural size. 

Metopaster Parkinsoni, Forbes, sp. (Page 31.) 

From the Upper Ghalh. 

2. Actinal aspect; natural size. (Coll. Brit. Mus., E. 5027.) 
a. Lateral view ; natural size. 

h. Ventro-lateral plate ; magnified 5 diameters, showing entrenclied pedicellaria. 
c. Supero-marginal plate ; magnified 3 diameters. 

Nymphaster Coombii, Forbes, sp. (Page 15.) 
From the Upper Greensand. 

3. Actinal aspect ; natural size. (Coll. Brit. Mus., -i8620.) 



PL. XIX. 



la- 




AH.Searle del efclvSi. 



Pitcher L^*^ imp . 



CRETACEOUS ASTEROID E A . 



PLATE XX. 

Pentaceros BULBiEERus, Fovhes, sp. (Page 77.) 

From the Upper Clmllc. 
Fig. 

1. Abactinal view ; natural size. (Coll. Brit. Mus., 40175.) 
a. Plate from dorsal part of disc ; magnified 3 diameters. 

h. Supero-marginal jjlate ; magnified 3 diameters. 

c. Plate from dorsal part of disc ; magnified 2 diameters. 

2. Abactinal view of two specimens ; natural size. (Coll. Brit. Mus., 48748.) 
a. Madreporite ; magnified (J diameters. 

J). Proximal supero-marginal plate ; magnified 4 diameters. 



1. 



lo. 




v>»*;j^ "» , ^'•-?7t 



7?-, » 





2b. 




la/. 







2ct/. 












A-H-Searledeletlitii, 



CRETACEOUS ASTEROIDEA 



Pitcher V^ imp. 



PLATE XXI. 

Pentaceeos bulbiferus, Forbes, sp. (Page 77.) 

From the Upper Chalk. 

Fig. 

1. View of the extremities of three arms and portion of disc ; natural size. 
(Coll. Brit. Mus., E. 5040.) 

a. Ventro-lateral plate; magnified 6 diameters. 

h. Actinal view of the extremities of two of the above arms ; natural size. 



Pentagonaster bobustus, n. sp. (Page 73.) 

From the Upper Challi. 

2. Abactinal aspect; natural size. (Coll. Brit. Mus., 48085.) 
a. Lateral view of an arm ; natural size. 

Pentaceros BULisiFEKUs, Forhes, sp. (Page 77.) 
From the U})per Chalk. 

o. Abactinal aspect ; natural size. (Coll. Brit. Mus., E. 5041 .) 

a. Madreporite ; magnified G diameters. 
4. Abactinal aspect ; natural size. (Coll. Brit. Mus., 40399.) 

a. Madreporite; magnified G diameters. 



PL . XX I 





3a 






, » « * ♦ r , a 

'-itififfM-^^mii^ 






AHSearle dd et lith 



CRETACEOUS ASTEROIDEA 



Piti'ner L':"; unp. 



PLATE XXII. 

Pentagonastek obtusus, Forbes, sp. (Page 74.) 

From the Uijper Chalk. 

Fig. 

1. Abactinal aspect ; natural size. (Coll. Brit. Mus., 40400.) 
n. Madreporite ; magnified 10 diameters. 

h. Lateral view of margin, abactinal side upwards ; natural size. 

2. Actinal aspect of two specimens; natural size. (Coll. Brit. Mus., 35481.) 
a. Lateral view of extremity of arm of the underlying specimen ; natural size. 

3 a. Dorsal view of extremity of arm ; natural size. (Coll. Brit. Mus., E. 5039.) 
h. End view of extremity of arm ; natural size. (Coll. Brit. Mus., E. 5038.) 

c. Side view of extremity of same arm ; natural size. 

d. Ventral end of extremity of same arm ; natural size. 

e. Supero-marginal plate ; magnified 3 diameters. 
/. Infero-marginal plate ; magnified 3 diameters. 
g. Adambulacral plate ; magnified 5 diameters. 



Pentaceeos Boysii, Forbes, sp. (Page 80.) 
From the Upper Ghallc. 

4. Abactinal view ; natural size. (Coll. Brit. Mus., 46600.) 

a. Isolated ossicle of disc : mao-nified 4 diameters. 

b. Isolated ossicle of disc ; magnified 4 diameters. 

c. Lateral view of arm ; natural size. 



la- 



mm 



IP 



PL. XXII. 



1& 



9MI^>J>' 



2 a, 



^^^ 





3a. 



a'^i 



3h 




3c 




3a( 




3e 





."J-i.Searle (H.etlith. 



3f 




4b 




^\ 



Pitcher L'^^imp 



CRETACEOUS ASTEROIDEA 



PLATE XXIII. 

Pentaceros Boysii, Forbes, sp. (Page 80.) 

From the Upper Chalk. 

Fig. 

1. Snpero-marginal plate; magnified 4 diameters. (Coll. Brit. Mus., 48083.) 

a. Lateral view of extremity of arm from which the above snpero-marginal plate 

was drawn ; natural size. 

b. Dorsal view of extremity of same arm ; natural size. 

Pentacekos bulbifeeus, Forbes, sp. (Page 77.) 
From the Tapper Challi. 

2. Abactinal aspect ; natural size. (Coll. Brit. Mus., E. 5042.) 

a. Madreporite; magnified 5 diameters. 

Pentaceros bispinosus, n. sp. (Page 87.) 
From the Upper Chalk. 

3. Actinal aspect ; natural size. (Coll. Brit. Mus., 35482.) 
ft. Actinal view of extremity of arm ; natural size. 

b. Infero-marginal plate ; magnified 3 diameters. 

c. Ventro-lateral plate ; magnified 4 diameters. 



PL. XXIII. 



(^: 



n 



'M 



20. 






let 



^^rVjl^^ 



3cc 

mi 




A.H.Searle del. el Irtb. 



Pitcher ll^ imp 



CRETACEOUS ASTEROIDEA 



PLATE XXIV. 

Pentacekos abbreviatds, n. sp. (Page 80.) 

From the Upi)er Chalk. 

Fig. 

1. Abactinal aspect; natural size. (Coll. Brit. ]\Ius., 575:^S.) 

a. Lateral view of arm ; natural size. 

b. Radial plate ; magnified 3 diameters. 

c. Two succeeding supero-marginal plates; magnified :] diameters 

Pentaceros C0R0NATU8, Forbcs, sp. (Page 82.) 
From the Lower Chidl-. 

2. Abactinal aspect ; natural size. (Coll. Brit. ]\Ius., o5480.) 

a. Plate of disc ; magnified 3 diameters. 

b. Supero-marginal plate ; magnified 3 diameters. 

c. Lateral view of arm ; natural size. 
[See also PL XXV, fig. 9.] 



PL. XXIV. 



Ic 





16 




• n^jj^^ kf ' W iwo?:!' 



2c 







26 





AJi.Searle del el liUi 



CRETACEOUS ASTEROIDEA 



2a 




Pitcher 'J.^ imp 



PLATE XXV. 

Nymphastee b.vdiatus, b. sp. (Page 73.) 

From the Lower Ghallc. 

Fig. 

1. Abactinal view ; natural size. (Coll. Brit. Mus., E. 375.) 

a. Lateral view of margin ; natural size. 

h. Supero-marginal ossicle ; magnified -i diameters. 

AsTROPECTEN ? u. sp. (Page 90.) 
From the Upper Oreensand. 

2. Abactinal view ; natural size. (Coll. Sedgwick Museum, Cambridge.) 
n. Isolated marginal ossicle ; magnified 4 diameters. 

Pentaoekos squamatlts, Forbes, sp. (Page 83.) 
From the Upper Chalk. 

3. Abactinal view ; natural size. (Willett Coll., Brighton Mus.) 
a. Madreporite ; magnified G diameters. 

I. Marginal view of arm ; natural size. 

c. Supero-marginal ossicle ; magnified G diameters. 

Pentaceros ocellatus, ForJjes, sp. (Page 85.) 
From the Upper Challc. 

4. Actinal view; natural size. (Coll. Brit. Mus., E. 5012). 
a. Ventro-lateral ossicle ; magnified 4 diameters. 

Pentaceros pistilliferus, Forbes, sp. (Page 88.) 
From the Upper Chalk. 

5. Ossicles of disc ; natm-al size. (Coll. Brit. Mus. ; from left to right the 

register numbers are E. 5037, 57G34, E. 2564.) 

Genus ? sp. ? (Page 93.) 

From the Chalk. 

G. Ossicles ; natural size. (Coll. Brit. Mus.) 
a. Isolated ossicle ; magnified 4 diameters. 

Pentaceros ? n. sp. (Page 89.) 
Frovi the Chalk. 

7. Marginal view of ossicles of arm ; natural size. (Coll. Bi'it. Mus., 5514.) 

Pentaceros ? n. sp. (Page 89.) 
From the Chalk. 

8. Marginal view of ossicles ; natural size. (Willett Coll., Brighton Mus.) 

Pentaceros coronatus, Forbes sp. (Page 82.) 

9. Madreporite; magnified 4 diameters. (Coll. Brit. Mus., 35480.) 



la-. 



PL. XXV. 





V-^'^ 



A 



MM 



«?:-T'.i^ 



Vo. 








'-'I77'',* 





3ct/. 




2a/ 




6. 





61X 




=# 



? 



A.H.oearle dd.et lith. 



W^ 



CRETACEOUS ASTEROIDEA . 




Pitcher L'-^ imp 



PLATE XXVI. 

Pentaceros puxctatus, n. sp. (Page 88.) 

From the Upper Challc. 
Fig. 
1. Abactiual view of remains of arms; natural size. (Coll. Brit. Mus., E. 2561.) 

a. Lateral view of margin; natural size. 

h. Enlai'o-ed view of single ossicle ; magnified 2 diameters. 



Pentaceros Botsii, Forbes, sp. (Page 80.) 
From the Upper Chalk. 

2. Actinal view ; natural size. (Coll. Sedgwick Mus., Cambridge.) 
((. Lateral view of margin; natural size. 

b. View of isolated ossicle ; magnified 4 diameters. 

MiTRASTEB coMPACTUs, Forle.-^, sp. (Page 67.) 
From the Upper Glialk. 

3. Abactinal view ; natural size. (Willett Coll., Brigbton Mus.) 

a. View of end of arm ; magnified 4 diameters. 

b. Lateral view of supero-marginal ossicles ; magnified 4 diameters. 

c. Lateral view of infero-marginal ossicles ; magnified 4 diameters. 

Calliderma M0SAiciJJ[, Forties, sp. (Page 9.) 
From tJte Lower Chalk. 

4. Actinal view of ambulacral groove; magnified 4 diameters. (Coll. Sedgwick 

Museum, Cambridge.) 

a. Actinal view ; natural size. 

b. Infero-marginal ossicle ; magnified 4 diameters. 



PL . XXVI , 




4;cv . 




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PLATE XXVII. 

LiNCKiA sp., n. sp. (Page 100.) 
From the Lower Chalk. 

Fig. 

1. Actinal aspect; natural size. (Coll. Brit. Mus., E. 5055.) 
a. Actinal aspect of portion of arm ; magnified -i diameters. 

Ophiuba Frnuu, u. sp., ex Forbes, MS. (Page lOo.) 
From the Flint Gravel. 

2. Actinal aspect, natui'al size. (Coll. Norwich Mus.) 

a. Cast of actinal aspect in region of mouth ; magnified 4 diameters. 

b. Abactinal aspect; natural size. 

Opuiura sebrata, Roemer. (Page 102.) 
From the Upper Chalk. 

3. Abactinal aspect; natural size. (Coll. Brit. Mus., E. 5043.) 

a. Abactinal aspect of segment of disc and two arms ; magnified 4 diameters. 
h. Abactinal view of two isolated vertebral ossicles of another specimen ; mag- 
nified 9 diameters. (Coll. Brit. Mus., E. 504G.) 

c. Side view of the same ossicles ; magnified '.) diameters. 

</. Anterior view of the same ossicles ; magnified 9 diameters. 
e. Posterior view of the same ossicles ; magnified 9 diameters. 

OphiuPvA parvisentum, n. sp. (Page 103.) 
From the Upper Chalk. 

4. Abactinal aspect of type specimen; natural size. (Coll. Brit. Mus., E. 5052.) 
a. Abactinal aspect of portion of one arm ; magnified 6 diameters. 



PL. XXVII. 





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PLATE XXVIII. 

Ophiotitanos tenuis, n. sp. (Page 104.) 

From the Lower Chall". 
Fig. 

1. Abactinal aspect of type specimen; natural size. (Coll. Brit. Mus., E. 5056.) 
a. Abactinal aspect of a segment of disc and two arms ; magnified 8 diameters 

(slightly restored). 

2. Actinal aspect of another example; natural size. (Coll. Brit. Mus., E. 5057.) 
a. Actinal aspect of a segment of disc and two arms ; magnified 8 diameters 

(slightly restored). 

OPHion'MNOS Lit;vi.<, n. sp. (Page 105.) 

From flic Loivcr Ohallc. 

o. Abactinal aspect ; natural size. (Coll. Brit. Mus., E. 5053.) 
it. Aljactinal aspect of a segment of disc and two arms; magnified 8 diameters 
(slightly restored). 

4. Abactinal aspect of another small example. (Coll. Brit. Mus., E. 5058.) 

It. x\bactinal aspect of a segment of disc and one arm ; magnified 10 diameters 
(slightly restored). 

OriiioTn'ANOS magnus, n. sp. (Page lOG.) 
From the Lower Clutlk. 

5. Actinal aspect of type specimen ; natural size. (Coll. Brit. Mus., E. 5060.) 
ti. Actinal aspect of portion of arm; magnified 4 diameters (slightly restored). 

Amphiura CEETACbiA, n. sp. (Page 107.) 
From the Lower Chalk. 

6. Actinal aspect of type specimen; natural size. (Coll. Brit. Mus., E. 5059.) 

(/. Actinal aspect of a segment of disc and two arms; magnified 10 diameters 
(slightly restored). 



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PLATE XXIX. 

Pycinasteb crassus, n. sp. (Page 96.) 

From the Upper Chalk. 
Fig. 

1. Actiual aspect of a small specimen ; natural size. (Coll. Brit. Mus., E. 2576.) 

2. Abactiual aspect of surface of arm of type specimen; natural si".e. (Coll. Brit. Mus., 35498.) 
a. Supero-marginal plate ; magnified 3 diameters. 

3. Supero-marginal plate ; uatui'al size. (Coll. Brit. Mus., E. 2631.) 
a. Side view of same ossicle ; natural size. 

4. Isolated veutro-lateral plate ; magnified 2 diameters. (Coll. Brit. Mus., E. 2632.) 
a. Isolated plate from abactiual surface of disc ; magnified 2 diameters. 

5. Madreporite ; natural size. (Coll. Brit. Mus., E. 2628.) 

Pycinastkr .senonbnsis, Valette, sp. (Page 95.) 
From the Upper Ghalk. 

6. Outer view of abactiual ossicle of disc ; natural size. (Dr. Blackmore's Collection.) 
a. Side view of same ossicle; natural size. 

Nymphastee. TvUgosus, 11. sp. (Page 94.) 
From the Lower Ghalk. 

7. Actinal aspect ; natural size. (Coll. Brit. Mus., 57516.) 
a. Infero-marginal plate ; magnified 6 diameters. 

Staubanderasteb abgus, 11. sp. (Page 99.) 
From the Upper Ghalk. 

8. Actinal aspect ; natural size. (Dr. Blackmore's Collection.) 
a. One of the veutro-lateral plates ; magnified 2 diameters. 

9. Inner view of three ossicles isolated from a specimen in the British Museum ; figured by Forbes ; 

magnified 2 diameters. E. 2566. [See also Plate XXV, fig. 6.] 
a. Outer view of same ossicles ; magnified 2 diameters. 

Abthbasteb cbistatus, n. sp. (Page 93.) 
From the Upper Chalk. 

10. Side view of segment of arm, restored; natural size. (Dr. Blackmore's Collection.) 
a. Outer view of a radiale ; magnified 4 diameters. 

h. Side view of same ossicle ; magnified 4 diameters. 

Abthbasteb Dixoni, Forbes, sp. (Page 91.) 

From the Upper Ghalk. 

11. Ossicle from abactiual surface of disc; natural size. (Coll. Brit. Mus., E. 5024.) 
a. The same ossicle ; magnified 3 diameters. 

Metopasteb cobnutus, Bladen, sp. (Page 117.) 
From the Upper Ghalk. 

12. Ultimate supero-marginal plate of adult specimen; magnified 2 diameters. (Dr. Rowe's 

Collection.) 

Ophiotitanos MAGNUS, II. sp. (Page 10(3.) 
From tlie Louier Chalk. 
13. Abactinal aspect; magnified 2 diameters. (Coll. Sedgwick Mus., Cambridge.) 



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