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A HISTORY
OF
BRITISH STARFISHES.
f r/
A HISTORY
OF
BRITISH STARFISHES,
AND OTHER ANIMALS OF THE CLASS
ECHINODERMATA.
By EDWARD FORBES, M.W. S. For. Sec. B. S. etc.
ILLUSTRATED BY WOODCUTS.
LONDON:
JOHN VAN VOORST, 1, PATERNOSTER ROW;
MDCCCXLI.
LONDON : PRINTED BY SAMUEL BENTLEY,
Bangor House, Shoe Lane.
TO
PROFESSOR AGASSIZ,
IN ADMIRATION OF HIS SCIENTIFIC LABOURS,
AND IN GRATITUDE FOR THE SERVICES HE HAS RENDERED TO
THE NATURAL HISTORY OF BRITAIN,
THIS VOLUME IS DEDICATED
UY A BRITISH NATURALIST.
PREFACE.
This History of the British species of a much neglected but beautiful and interesting class of animals originated in an attempt to revise the characters of such Starfishes as inhabit the Irish Sea, and to introduce the generic arrangements proposed by Professor" Agassiz, which I laid before the Wernerian Society, with the approbation of its distinguished president, Professor Jameson, and which was published in 1839 in the eighth volume of its Transactions. Without the kind assistance of my brother naturalists, the materials for the following pages could not, however, have been gathered. To my friend Mr. John Groodsir I am especially indebted for assistance and ad- vice. From Mr. Thompson of Belfast a great portion of my information has been derived ; and the materials which he had been collecting for several years, in order to prepare an account of the Irish species, were most liberally, and without reserve, placed in my hands, as were, also, with like kindness, Mr. Robert Ball's collections for an account of the Echini dae. In Scotland 1 have derived most valu- able aid from Professor Jameson, Dr. Johnston of Berwick,
Vlll PREFACE.
and Dr. P. Maclagan; in England from Mr. Alder, Mr. Bean of Scarborough, Mr. Bellamy of Plymouth, and Mr. Gray of the British Museum, and from many other gentlemen in both countries, and in the sister island, whose assistance I have recorded in the text. In Dublin Captain Portlock most liberally permitted me to examine the Ordnance col- lection. To all these gentlemen I return my fervent thanks, also to Professor Agassiz, who most kindly per- mitted me to make use of the notes he had made on the British collections of these animals during his last visit to our country.
Nor must I forget favours of the pencil. To my friend Mr. Gr. J. Bell the volume is indebted for some of its most interesting embellishments : Mr. Alder and Mr. Thomp- son have also contributed to the ornamental part. The wood-cutting speaks for itself, — thanks to Mr. Bastin, who in the most praiseworthy maimer made himself acquainted not merely with the drawings, but with the texture and appearance of the animals themselves, in order the better to express them.
With three exceptions the figures of species are from my own drawings, and with a view to secure correctness were mostly drawn on the wood by myself. In the text I have endeavoured faithfully to do justice to preceding- writers, and rarely have quoted a synonym which I have not myself verified. I have endeavoured to bring the subject as near as possible to the present state of science, and trust that few memoirs essential to my purpose have escaped me. I should have wished to have made more
PREFACE. IX
use than I have done of the valuable papers on the Echi- nidee by M. Desmoulins, but could lay hands on a portion of them only. Since I commenced the publication two papers have appeared which I must notice, as they add several to my enumeration of the synonyms of the Star- fishes. The one is a Memoir by one of the greatest living- physiologists, Muller of Berlin, on the genera of the Star- fishes, read before the Berlin Academy in April 1840. This paper must be praised on account of the excellent way in which the characters of the genera are drawn up. The chief novelty is the employment of the anus of Star- fishes (or anal pore) as a source of family distinction, which aperture Muller describes as existing in all Starfishes saving Asterias proper, and a new genus, Hemichemis, which seems identical with my previously constituted Luidia. His genus Crossaster, also, is my Solaster, published the year before. Several generic names previously adopted by Agassiz and Nardo are wantonly changed ; thus, Uras- ter is turned into Asterocanthium, and Palmipes into As- teriscus, with which he unites Asterina. In this paper Muller maintains that one of the five intermediate inferior plates of the Ophiuridse bears a madreporiform tubercle, or rather corresponds to that body, a view which I am not inclined to adopt.
The other Memoir to which I must allude is one by Mr. Gray on the Starfishes, which he calls the class Hypostoma, and defines somewhat ambiguously, published simultane- ously with my two first numbers, in the Annals of Natural History. I am afraid I must censure Mr. Gray for chang-
X
PKEFACE.
ing names still more than Muller, and with less reason. It is a pity zoologists do not take a lesson from their fellow labourers in the field of Nature, the botanists, in this respect. Mr. Gray has increased the confusion by giving fragments of descriptions instead of generic and specific characters, probably from carrying too far a laudable desire for brevity. His essay deserves praise, however, for re- cording many new foreign habitats of the beautiful animals he catalogues.
•
INTRODUCTION.
The Echinodermata constitute one of the three great classes into which the Radiata are divided. The radiate type presents us with animals which either have their parts arranged in a ray-like manner round a common centre, or have their hilaterality so modified as to give them a star- like form. The Zoophytes, the Medusa?, and the creatures to which this volume is devoted, constitute the type. The Echinodermata are most highly organized, much more so than the Polypes ; they are almost all free animals, creep- ing ahout at the bottom of the sea ; and as the greater number of species are covered with a coriaceous skin, which is commonly strengthened by calcareous plates or spines, they have derived their general appellation from that re- markable character, which at once distinguishes them from the Medusa;, free swimming animals of the most delicate and membranous texture.
Throughout animated Nature forms and structures merge into each other. While the central groups of a type pre- sent its essential characters, the more distant families approach in appearance and habits to the members of some other great class of forms. This is equally true respecting small as well as large groups. Thus, the class of Radiata before us presents examples, at one extreme, of animals truly symmetrical, and, at the other, of species which ap- proach either in general form or in their early life to the Aniorphozoa, the lowest of animal types. For example,
Xll INTRODUCTION.
while the first state of a Comatula is analogous to a sponge or a Polypidom, the highest groups of Echinodermata are creatures resembling Mollnsca or Annellida. Correspondent with the progression of form is the progression of organiz- ation and of sagacity.
Externally, the majority of Echinodermata are radiated, and the lowest groups resemble Polypes. The first species figured in this history is the Feather-star, a creature which in its youth is fixed and pedunculate, like a Zoophyte ; in its adult state free and star-like. When dredging in Dub- lin Bay in August 1840, with my friends Mr. R. Ball and W. Thompson, we found numbers of the Phytocrinus or Polype state of the Feather-star, more advanced than they had ever been seen before, so advanced that we saw the creature drop from its stem and swim about a true Co- matula ; nor could we find any difference between it and the perfect animal, when examining it under the micro- scope. From the Comatula we proceed onwards through forms gradually changing character, until in the Sea- Urchins we have the true representatives of the Echino- dermata. In them we have the perfection of an Echino- dermatous integument. We have arrived, as it were, at the summit of a pyramid, and we descend through a series of forms as gradually conducting us to the Mollusca and the Vermes. The Holothuriada?, which at first have the ap- pearance of soft Sea-Urchins, gradually change their forms, and become more and more Molluscan in character. The Sipunculidae progress in like manner towards the Annel- lida ; and in the animals described last in this volume, we see Radiata, which have so put on the garb of worms that by many naturalists they have been classed as such.
Every great class in the animal kingdom, when con- sidered anatomically or physiologically, may be looked on
INTRODUCTION. XIU
as the completing of some organ or function, even as zoolo- gically it represents the completing of some important modification of form. In the lowest division of the Radi- ata, that of Zoophytes, the digestive system has passed through all its essential changes, therefore we do not see a true progression of the organs of that system among the Echinodermata. We find its variations depend rather on the circumstances under which the species are destined to live than on any progression of structure. Thus it appears anomalous at first, that the lowest Echinodermata should have digestive organs of more complicated nature than some higher tribes ; that the Feather-star should have an intestinal canal with two orifices, whilst all the Ophiuridpe and many true Starfishes have but one ; or that the Splancno-skeleton (dental apparatus) of the Echinidse should be more highly developed than that of the Holo- thuriadse ; but looking at the system according to the view I have taken of its completion in a lower tribe, this is what we should expect. Not so, however, with all the functional systems. The respiratory goes through a series of modifications complicating as we advance, so also do the circulatory and the nervous. But it is the muscular which is especially presented in all its essential modifica- tions in the class before us, from the first appearance of a contractile tissue, as seen in the granular tissue of the lowest Echinodermata, to its perfect developement in the complicated muscular mechanism presented by many of the Vermigrade species.
The system most characteristic of the Radiate tj-pe is the Aquiferous, or apparatus for a water circulation ; in- deed, it can scarcely be said to exist in any of the other types. It is chiefly developed in the Arachnodermata and Echinodermata, and in the last is intimately connected
XIV INTRODUCTION.
with the movements of the animals ; for it is by means of this water circulation that the suckers or cirrhi are enabled to act as organs of progression. In many species of the most typical group, that of Echinidse, we find a portion of the dermato-skeleton turned in, as it were, to form arches for the protection of the water-canals, thus evidencing their great importance in those creatures. Among the Annel- lidous Echinodermata, however, the aquiferous system seems altogether to disappear.
On the modifications of this characteristic system, its presence or absence, and its combination with the tegu- mentary system for purposes of motion, I have founded my arrangement of the Echinodermata. I look upon the Echi- nodermata and Araclmodermata as two parallel groups, and hold it as a law that the divisions of parallel groups should he based on a common principle. The orders of the latter class have always been founded on the modifications of their organs and modes of progression : the orders of the class before us I have founded on the same consider- ation, and need only call the attention of the philosophical zoologist to the naturalness of the divisions so formed, and to their equidistance from each other, and I feel confident he will acknowledge the truth of my arrangement.
Order I. Pinnigrada. Crinoide^e — First appearance of cirrhi, springing from brachial membranes, which, with the true arms, form the organs of motion. II. Spinigrada. Ophiurid;e — Disappearance of brachial membranes, cirrhi as before ; true arms clothed with spines for motion. III. Cirrhigrada. Asteriad^; — Arms disappear ; body more or less lobed, and lobes channeled beneath for cirrhi, which act as suckers, and are the organs of motion.
INTRODUCTION. XV
Order IV. CiRRHi-SriNiGRADA. Echinidttc — Gradual disappear- ance of lobes ; cirrhifcrous canals appearing as avenues where cirrhi act as in Order III. but are assisted by mobile spines clothing the integument. V. Cirrhi-Vermigrada. Holothuriad^e — Lobes disap- pear ; motions effected by avenues of cirrhi, assisted by contraction and extension of the soft body. VI. Vermigrada. SipunculiDvE — Cirrhi become obsolete and disappear ; motion effected by the contraction and extension of the animal's body.
A glance at this arrangement will at once show that it is most natural. There is nothing novel in it as regards the constitution of the groups, saving the recognition of the Ophiuridse as an order equivalent to the other orders ; but as an explanation of the true nature and relation of the Echinodermatous tribes, I prefer it to any arrangement at present used, and have accordingly followed it through- out this work.
All the Radiata are greatly influenced in the arrangement of their parts by some definite number. In the Echino- dermata the reigning number is five. The name of " five- fingers," commonly applied by mariners to the Starfishes, is founded on a popular recognition of the number regnant. It has long been noticed. Among the problems proposed by that true-spirited but eccentric philosopher, Sir Thomas Browne, is one, " Why, among Sea-stars, Nature chiefly delighteth in five points V and in his Garden of Cyrus he observes, " By the same number (five) doth Nature divide the circle of the Sea-star, and in that order and number disposeth those elegant semicircles or dental sockets and eggs in the Sea Hedge-hog." Among the lower and the typical orders we find this number regulating the num- ber of parts. Every plate of the Sea-Urchin is built up of
XVI INTRODUCTION'.
pentagonal particles. The skeletons of the digestive, the aquiferous, and the tegnmentary systems, equally present the quinary arrangement ; and even the cartilaginous framework of the disk of every sucker is regulated by this mystic number. When the parts of Echinoderms deviate from it, it is always either in consequence of the abortion of certain organs, or it is a variation by representation, that is to say, by the assumption of the regnant number of another class. Thus do monstrous Starfishes and Urchins often appear quadrate, and have their parts fourfold, as- suming the reigning number of the Actinodermata, con- sistent with a law in which I put firm trust, that when •parallel groups vary numerically by representation they vary by interchange of their respective numbers.
In this short introduction I have rather given the gene- ralities of the subject than details of structure, for which I would refer the reader to the excellent account of the anatomy of Echinodermata given by Professor Jones in his Outlines of the Animal Kingdom. I shall conclude by presenting a tabular view of the distribution of our native species. In the first of the two following tables, the numbers of species of each family known to inhabit the several zones of the sea is given ; in the second a view of their distribution in the various provinces of the British seas, with such foreign localities as are recorded. I have divided the marine provinces thus : — I. Thulean, including the Orkney and Shetland Isles. II. Hebridean. III. Scottish eastern coast. IY. English eastern coast. V. English Channel. VI. St. George's Channel. VII. South- ern, the district between Land's End and Cape Clear. VIII. South-west Irish. IX. North-west Irish. X. The Clyde province and North Channel. XI. The Irish Sea.
INTRODUCTION.
XVII
I.
Table of Zonal Distribution.
8* ■"3 |
8 |
||||||
Zones of the Sea. |
8 aj 3 |
8 3 |
8 •« .2 |
8 "S |
3 |
3 |
Total. |
fi |
t/1 |
M |
Oh |
||||
U |
O |
< |
w |
w |
CO |
||
Littoral .... |
0 |
4 |
6 |
3 |
1 |
2 |
16 |
Laminarian . |
1 |
5 |
C |
4 |
5 |
6 |
27 |
Coralline .... |
1 |
9 |
11 |
7 |
12 |
9 |
42 |
Deep-sea Coral . . |
0 |
3 |
CI O |
3 |
? |
? |
9 |
XV111
INTRODUCTION.
II.
Table of the Geographical Distribution of the British Species of Echinodermata.
Genera and Species. |
British Distribution. |
General Distribution. |
|
PINNIGRADA. |
|||
I. |
Comatula. Lain. |
||
1 |
rosacea. Link. SPINIGRADA. |
I. II. VI. VII. X. XL |
Scandinavia, Mediter- ranean. |
II. |
Ophiura. Lain. |
||
1 |
texturata. Lam. |
L— XI. |
Scandinavia, Celtic, Mediterranean. |
2 |
albida. Forbes. |
I.— XL |
North Sea. |
III. |
Ophiocoma. Agas. |
||
1 |
neglecta. Johnst. |
I.III.-VI.VIII.-X1. |
|
2 |
Ballii. Thomp. |
VI. |
|
3 |
punctata. Forbes. |
III. |
|
4 |
riliformis. Mul. |
VIII. X. |
Norway. |
5 |
brachiata. Mont. |
V. X. |
|
6 |
granulata. Link. |
I.V.VI. X. XL |
Scandinavia. |
7 |
bellis. Link. |
I.— VI. X. XI. |
Arctic and Scandina- vian Seas. |
8 |
Goodsiri. Forbes. |
I. III. |
|
9 |
rosula. Link. |
I — XI. |
Arctic, Scandinavian, Celtic, and Mediter- ranean Seas. |
10 |
minuta. Forbes. |
VII. XL |
|
IV. |
Astrophyton. Link. |
||
1 |
scutatuni. Link. CIRRHIGRADA. |
I. VII. |
Arctic and Scandina- vian Seas. Indian Ocean ? Mediter. ? |
V. |
Uraster. Agas. |
||
1 |
glacialis. Lin. |
II. VII. VIII. X. XL |
All the European seas. |
2 |
rubens. Lin. |
I.— XL |
Throughout the seas of Europe. |
3 |
violacea. Mul. |
I.— IV. VI. VII. X. |
Norwegian and Baltic |
XI. |
Seas. |
||
4 |
hispida. Pen. |
II. III. X. XI. |
|
VI. |
Cribella. Agas, |
||
1 |
oculata. Pen. |
I.— IV. VI. VII. X. |
Norway ? West of |
XI. |
France. |
||
2 |
rosea. Mul. |
VII. X. |
|
VII. |
Solaster. Forbes. |
||
1 |
endeca. Lin. |
I.III.IV.VI.VII.XI. |
Scandinavia. |
2 |
papposa. Lin. |
I.— XL |
Scand. and Celt. Seas. Mediter.? Asia? |
INTRODUCTION.
XIX
Genera and Species. |
British Distribution. |
General Distribution |
|
VIII. |
Palmipes. Link. |
||
1 |
membranaceus. Retz. |
IV. VII. X. XL |
Arctic, Scandinavian, and Mediter. Seas. |
IX. |
Asterina. Nardo. |
||
1 |
gibbosa. Pen. |
II. V.— XI. |
Celt. & Mediter. Seas. |
X. |
Goniaster. Agas. |
||
1 |
Templetoni. Thomp. |
I.V.VII. X. XL |
|
2 |
equestris. Gmel. |
III. IV. VII. |
North Sea. |
XL |
Asterias. Lin. |
||
1 |
aurantiaca. Lin. |
I. III.— XL |
All the European seas. |
XII. |
Luidia. Forbes. |
||
1 |
fragilissima. Forbes. CIRRHI-SPINI- GRADA. |
I. III. IV. VII. VIII. X. XI. |
|
XIII. |
Cidaris. Leske. |
||
1 |
papillata. Flem. |
I. |
Norway. |
XIV. |
Echinus. Lin. |
||
1 |
sphaera. Mul. |
I.— XL |
Arctic, Northern, and Celtic Seas. |
2 |
miliaris. Leske. |
I.— VII. X. XL |
|
3 |
Flemingii. Ball. |
I. VII. |
|
4 |
lividus. Lam. |
VIII. IX. |
Mediter. Portugal ? |
5 |
neglectus. Lam. |
I. |
West of France. |
XV. |
EcHINOCYAMUS. Leske. |
||
1 |
pusillus. Mul. |
I.— XL |
Norway. West of France. |
XVI. |
ECHINARACHNIUS. Leske. |
||
1 |
placenta. Gmel. |
I. |
Canada, Asia ? |
XVII. |
Spatangus. Klein. |
||
1 |
purpureus. Mul. |
I. III. IV. VI. XI. |
Scandinavia, Mediter- ranean. |
XVIII. |
Brissus. Klein. |
||
1 |
lyrifer. Forbes. |
X. |
|
XIX. |
Amphidotus. Agas. |
||
1 |
cordatus. Pen. |
I.— XI. |
Northern seas. |
2 |
roseus. Forbes. CIRRHI-VERMI- GRADA. |
I.III.VI.VII.X.XI. |
|
XX. |
Psolus. Oken. |
||
1 |
phantapus. Lin. |
I. III.— V. X. XL |
Norway. |
XXI. |
Psolinus. Forbes. |
||
1 |
brevis. F. and G. |
I. X. |
|
XXII. |
Cucumaria. Blainv. |
||
1 |
frondosa- Gunner. |
I. III. |
Norway. |
2 |
pentactes. Mul. |
III.— V. X. |
Northern and Celtic Seas. |
3 |
communis. F. and G. |
III. VII. X. |
|
4 |
fusiformis. F. and G. |
I. |
|
5 |
hyalina. Forbes. |
I. |
|
6 |
Drummondii. Thomp. |
X. |
|
7 |
Hindmanni. Thomp. |
VIII. X. |
|
8 |
fucicola. F. and G. |
I. |
XX
INTRODUCTION.
Genera and Species. |
British Distribution. |
General Distribution |
|
XXIII. |
Ocnus. F. and G. |
||
1 |
brunneus. Forbes. |
III. X. XL |
|
2 |
lacteus. F. and G. |
I. III. X. |
|
XXIV. |
Thyone. Oken. |
||
1 |
papillosa. Mul. |
I. III. VIII. X. XL |
Norway. |
o |
Portlockii. Forbes. |
X. |
|
XXV. |
Chirodota. Esch. |
||
1 |
digitata. Montagu. VERMIGRADA. |
V. |
|
XXVI. |
Syrinx. Bohadsch. |
||
1 |
nudus. Lin. |
IV. V. VII. |
Celtic Seas. Mediter. |
2 |
papillosus. Thonip. |
VIII. XL |
West Indies. |
3 |
Harveii. Forbes. |
V. |
|
XXVII. |
Sipunculus. Lin. |
||
1 |
Bernhardus. Forbes. |
I. XL |
Norway, France. |
Johnstoni. Forbes. |
III. V. ? |
||
XXVIII. |
Priapulus. Lam. |
||
1 |
caudatus. Lam. |
I. III. IV. X. |
Arctic and Scandina- vian Seas. |
XXIX. |
Thalassemia. Cuv. |
||
1 |
Neptuni. Gaertner. |
IV. |
|
XXX. |
Echiurus. Cuv. |
||
1 |
vulgaris. Savig. |
III. |
Belgic coast. |
BRITISH ECHINODERMATA.
CRINOIDE^:,
OR P1NNIGRADE ECHINODERMATA.
One of the most remarkable phenomena displayed to us by the researches of the geologist, is the evidence of the existence, in primaeval times, of animals and plants, the analogies of which are now rare or wanting on our lands and in our seas. Among those tribes which have become all but extinct, but which once presented numerous generic mo- difications of form and structure, the order of Crinoid Star- fishes is most prominent. Now scarcely a dozen kinds of these beautiful animals live in the seas of our globe, and
CRIXOIDE.E.
individuals of these kinds are comparatively rarely to be met with : formerly they were among the most nnmerons of the ocean's inhabitants, — so numerous that the remains of their skeletons constitute great tracts of the dry land as it now appears. For miles and miles we may walk over the stony fragments of the Crinoidesc ; fragments which were once built up in animated forms, encased in living flesh, and obeying the will of creatures among the loveliest of the inhabitants of the ocean. Even in their present disjointed and petrified state, they excite the admiration not only of the naturalist but of the common gazer ; and the name of Stone-lily popularly applied to them, indicates a popular appreciation of their beauty. To the philoso- pher they have long been subjects of contemplation as well as of admiration. In him they raise up a vision of an early world, a world the potentates of which were not men but animals — of seas on whose tranquil surfaces myriads of convoluted Nautili sported, and in whose depths millions of Lily-stars waved wilfully on their slender stems. Now the Lily-stars and the Nautili are almost gone ; a few lovely stragglers of those once-abounding tribes remain to evidence the wondrous forms and structures of their com- rades. Other beings, not less wonderful, and scarcely less graceful, have replaced them ; while the seas in which they flourished have become lands, whereon man in his columned cathedrals and mazy palaces emulates the beauty and symmetry of their fluted stems and chambered shells.
Throughout the animal kingdom we find groups which, when compared with a neighbouring group of equal value, present higher affinities and yet lower analogies. The order before us is a good example, and may serve as an explanation of this rather obscure-sounding doctrine. The
CRIXOIDE.E.
Crinoids as analogues of the Polypes are lower than the Asteroids, but as allies of the Asteroids are their superiors. An Enerinite is a Polype-like Starfish. Suppose, as Pro- fessor Jones has well suggested, an Ascidioid Zoophyte strengthened by depositions of calcareous matter in its arms and stems, and you have a Orinoid Starfish. In that point of view the latter is a link between the Echi- noderms and the Polypes. But the link is, as it were, lateral — a link of analogy — for the Ascidioid Polypes themselves are higher in their organisation than many Echinoderms. Their digestive system is more developed than that of the Starfishes. In them we see for the first time Echinoderms with two openings to their digestive canal. Their generative system is spread over the tegu- mentary covering of their body and arms, they have tentacular filaments like those of the Ophiurse ; and the pinna; with which the arms are furnished, have the skin so developed on their sides as to enable them to serve as fins wherewith the animal can swim through the water in the manner of the Medusae, whence the name of Pinni- grade Echinoderms which I have applied to them, in- dicative of this mode of progression.
It will be seen in the account of the Comatula, or Feather-star, that we believe that animal to be fixed and stable, like one of the fossil Encrinites, when it is young. At the same time it is very probable that there are Cri- noids which are stalked throughout life, and that most of the fossil species were of such a nature. Tribes which form a link between one mode of existence and another, generally present examples of both and combinations of both. Thus among the Polypes do we find in the family TubulariadcG the connecting link between the naked and clothed Hydroid Polypes, animals which are naked
B 2
CRINOIDEJE.
throughout life, others naked through a part of their existence, and others which are enclosed in a tube throughout their lives. In like manner may we expect to find in the order of Crinoidese animals fixed through- out life, others fixed through a portion of their existence only, and others which are free almost from their births. As yet, however, we know so little of the history of the tropical species that we cannot pronounce with certainty, and at present we can only recognise two families of Crinoids as properly constituted, such as are stalked as the Encrinites and the Comatula, and such as are sessile, as the genus Holopus of M. D'Orbigny. This division can only be regarded as provisional.
ROSY FEATHER-STAR.
CRINOIDEJE.
Genus Comatula. Lamarck.
Generic Character. — Body having five bifurcated pinnated arms : when adult, free, with simple filiform jointed appendages attached to the sides of its dorsal disk. When young, fixed on a long simple jointed (pentangular) stalk. (Phy- tocrimis.)
ROSY FEATHER-STAR.
Comatula rosacea. Link.
Specific Character. — Rays dorsally rounded, with only two joints below the bifurcation of each.
Stella (decamcros) rosacea, Link, p. 55, t. xxxvii. f. 66. Encyc. pi.
cxxiv. f. 6. Stella (decamcros) barbata, Link, t. xxxvii. f. 65.
0 C'RINOIPE.E.
Asterias bifida and A. decacnemos, Pennant, Brit. Zool. IV. pp. 05, (>G, No. 70,
71, tab. xxxiii. f. 71. Asterias peciinata, Adams, Lin. Trans. V. 10.
Comatula Mediterranean Lam. 1 Edit. II. p. 535. 2 Edit. III. p.
210. Sars, Besk. og Jagt. p. 40, pi. viii.
fig. 19. Comatula rosacea, Fleming, Brit. An. p. 490. Blainv. Man.
d'Actin. p. 248. Forbes, Wern. Mem.
VIII. p. 128. Comatula barbata, Fleming, Brit. An. p. 490.
Comatula fimbriata, Miller, Crinoideae, p. 132, pi. i.
Alecto Europcea, Leach, Zool. Misc. II. p. 62.
Junr. Pentacrinus Europceus, Thompson, Mem. on. Pentac. Eur. t. i. and ii.
Edin. Phil. Joum. vol. xx. p. 35, pi. ii.
Fleming, Brit. Anim. p. 490. Buckland's
Bridg. Tr. pi. lii. f. 2. Phytocrinm Europceus, Blainv. Man. d'Actin. p. 255, pi. xxvii.
f. 1—8.
After what I have said of the former importance of the Crinoid Starfishes in the economy of the world, it need scarcely be remarked that the history of the only Crinoid animal at present inhabiting our seas, at one time so full of those beautiful and wonderful creatures, must present many points of great interest not to the zoologist only, but also to the geologist. And in truth the history of the Feather-star, — for so on account of its plumose ap- pearance I would designate the Starfish called by na- turalists Comatula, — is one of the little romances in which natural history abounds, one of those narrations which, while believing, we almost doubt, and yet, while doubt- ing, must believe. Nevertheless, there is nothing incon- sistent with the creature's position in the animal kingdom in the account of the developement of the Comatula ; but before speaking of that subject, it is best we describe the animal in all its parts.
The adult Comatula consists of a cup-shaped calcareous base, in the concavity of which is placed a soft body, and on the convexity a number of slender, jointed, simple arms. The base branches into five arms, which very soon bifur-
ROSY FEATHER-STAR.
cate, so that as the two branches of each arm are very long-, and the undivided part extremely short, the animal appears to be ten-armed. These arms are pinnated with single pinna?, each of which bears a membranous expansion and other organs, all which parts we must now examine in detail.
1. The cup-shaped base is very convex on one side, and deeply concave on the other. The convex part consists of a somewhat pentangular disk or true base, and five sides or surfaces. The disk is smooth, but the sides are punc- tate, with concave hexagonal impressions, the largest of which are lowest. These are the sockets of the filaments, which vary in number according to the age of the animal, being from twenty to thirty in one full grown. There are also perforations on these punctate sides, which seem to be the openings of canals branching out from five main canals, which proceed from near the bottom of the con- cavity or cup. The disk is imperforate ; but when we make a section of the cup, we find a funnel-shaped cavity, which extends very nearly to the surface of the centre of the disk. The concavity of the cup presents ten canali- cnlated radiating ribs, five of which are more depressed than the others.
2. The filaments, jointed appendages, or simple arms, with which the convexity of the base is furnished, are calcareous and jointed ; the joints a little concave in the middle, and thickest at each end, so that the articulations have a slightly knotted appearance. These filaments are not all alike ; there are two kinds of them. The larger have fourteen joints, and a small, thick, blunt, curved claw, which is smaller than the joints and has a horny lustre : the smaller filaments have eighteen rough joints, and an almost straight claw, which is larger than the joints pre- ceding it.
8
('RINOII)K-K.
,'
^^S
] , Part of an arm with two pinnae. 2, A single pinna. 3, One of the ten- tacula. 4, Claw at the extremity of a pinna. 5, Claw of a filiform pro- cess : all magnified.
3. The arms are five, but bifurcate shortly after their origin, each of the bifurcations being very long and taper- ing to its extremity. Before bifurcating the arms are simple ; but the bifurcations are pinnated with calcareous, jointed, slender pinnse, which, when fully developed, con- sist each of from twenty-two to twenty-four perforated joints, and a claw of five or six crooked finger-like hooks at the end. The joints are rough as if covered with short spicule ; but the claws are smooth. The arms consist of calcareous joints with sloping diagonal segments, which can be separated from each other even as the joints can. The joints of the pinnse are sometimes similarly con- structed. In a full-grown Feather-star there are thirty- four pinnse on each side of each bifurcation.
ROSY FEATHER-STAR. 9
4. The soft parts consist of the stomach, which is placed in the concavity of the cup, and of a membrane and ap- pendages which cover the surface of the stomach, and ramify over the arms and along the pinna?. The stomach is thin and membranous, and opens externally by a sub- central mouth, the margins of which are crenate. From its side, opening into it by a rather small aperture, pro- ceeds an intestine, which winds round the body, and opens externally by a laterally-placed proboscis-shaped anus, the aperture of which is round, crenate, and wide, though not so wide as at the base. This curious vent has been mis- taken by many authors for a mouth, and has greatly puzzled others ; and M. de Blainville suggested that it might be connected with the functions of respiration or generation : but any one who examines the Comatula alive, or dissects a specimen well preserved, will not doubt it is a true vent. The membrane or skin which covers the stomach is also the covering of the arms, and branches out to the extremity of their pinna?. It is channelled in the following manner : — From the mouth proceed five canals, fringed at their edges, which radiate and bifur- cate, though not equally, in order to run up the bi- furcations of the arms; tor, looking at the body from above, the origins of the arms are hidden. These canals run up the arms to their extremities, and also to the extremities of all their pinna? ; and the membranes which depend from the pinna? are very ample, and furnished with numerous long white pinnated tentacula or cirrhi. At certain seasons this membrane bulges out on the pinna?, and is then filled with white milky globules ; but at all times the margins of the canals, on the body, on the arms, and on the pinna?, are studded with round brown dots, placed in regular rows and at regular distances. They
10 CRINOIDEJE.
are not, however, all of the same size, nor placed on all parts equally distant from each other ; for on the body they are small, and the margins of the canals appear lineated with them, but on the arms and pinna? they are larger and more distant. On the extreme pinna? they are very small, proportionate to the length of the pinna and the developement of the membrane, for their number is the same on all the pinna?. Thus, as there are thirty- four pinna? on each side of each of the ten bifurcations of the arms, and eighty-four brown spots in each, the whole ten armlets will present the great number of 57,120 of these spots, which appear to be the animal's ovaries. The white milky fluid, on the contrary, would seem to be seminal, as minute rounded, active animalcules are seen in it when a drop is highly magnified.
The whole of the animal is of a deep rose colour, dotted by these brown ovaries, and fringed with the transparent cirrhi. The description here given I have carefully drawn up from specimens before me, taken by myself in the Irish Sea, without adding several points observed by other describers, but which I have not seen.
M. Sars says there " are found on the upper part of each arm, above the proper fins, on each side, four or five thinner cylindrical thread-like fins (or pinna?) of greater or less length, some consisting of seven or eight, others of nearly twenty calcareous joints, which are also furnished with feet"" (cirrhi). M. Dujardin states that the inferior or ventral surface of the arms and pinna? is provided with a double range of fleshy tentacula, protected by a double range of fleshy lamella?, presenting between them a furrow filled with papilla? furnished with vibratile cilia, by the motions of which animalcula? and microscopic vegetables are conducted along the arms to the mouth, in order to
ROSY FEATIIER-STAR.
11
serve as food for the animal. This observation T cannot confirm, not having- ever found, any vibratile cilia on this animal, saving on the walls of its stomach. Several authors state that besides the stomach and intestine, the body is provided with a liver.
" In the months of May and June,11 says Mr. J. V. Thompson, " the full-grown Comatidce. have the mem- branous expansion inside each of the pinnae considerably extended, at least as far as the fifteenth or twentieth pair ; these, which are the matrices or conceptacula, at length show themselves distended with ova, which in July, or even earlier, make their exit through a round aperture on the facial side of the conceptaculum, still, however, ad- hering together in a roundish cluster of about a hundred each by means of the extension and connection of their umbilical cords.11
And now commences the strange chapter in the history
of the Feather-star ; a history
which has excited much dis- cussion in the world of science.
In the year 1823, Mr. J. V.
Thompson discovered in the
Cove of Cork, a singular little
pedunculated crinoid animal,
which he named Pentacrinus
Europaus. This creature was
taken attached to the stems of
Zoophytes of different orders.
It measured about three-fourths
of an inch in height, and
resembled a minute Comatula
mounted on the stalk of a
■ .
12
CRIN01DE.E.
Pmtacrinus. The discovery excited great interest both at home and abroad ; for it was the first animal of the Encrinite kind which had been seen in the seas of Europe, and the first recent Encrinite which had ever been examined by a competent observer in a living state. The base of its column, which was flexible and bent, and twisted itself at the will of the animal, was expanded into a convex calcareous plate, by which it attached itself to foreign bodies. From the centre of the plate arose the column, built up of about twenty- four joints, and somewhat thicker towards its upper extremity than at the lower. Round its uppermost joints, springing from the base of its cup-like body, was a row of jointed filaments with hooked extremities. The body bore five bifurcating arms, each bifurcation consisting of about twenty-four joints, in the older specimens pinnated, in the younger simple. Along the sides of each arm were rows of dark spots, and from the membrane of the arms proceeded fleshy flexible ten- tacula. The body resembled that of Comatula in its structure, having a separate mouth and proboscidiform lateral anus. The youngest specimens found had neither column nor arms, but appeared like little clubs fixed by a spreading base, and sending out from their summits a few pellucid tentacula. Dr. Fleming first proposed the generic separation of this animal from Pentacrhms, and suggested the propriety of associating it with Comatula by an im- proved definition of the family Comatulidce. M. de Blain- ville afterwards constituted for its reception the genus Phytocrinus, and associated it with the Encrinites. But in 1836, Mr. J. V. Thompson published a second memoir on the subject in the Edinburgh New Philosophical Jour- nal, communicating the results of further researches. In
ROSY FEATHER-STAR. 13
that paper he maintained the proposition that his Penta- crinus Europ&us was only the young of Comatula ; that the Feather-star comiflenced life as an Encrinite, and thus, as it were, changed its nature from a pseudo-polype