256 Tlie British Star-Fishes. 



the pedicellarias of Echinoderms are somewhat similar in appear- 

 ance, they cannot be supposed to perform a like office in ani- 

 mals so well endowed with locomotive powers, and so voracious 

 in their attacks upon creatures almost as large as themselves, 

 such as oysters and other molluscs. Star-fishes are, indeed, 

 held to be the most destructive enemies of oyster-beds. 



We must not conclude our paper without some notice of 

 the Feather-star (Comatula rosacea), perhaps the most inter- 

 esting of British star-fishes — one which is unique in the grace- 

 fulness of its form and the exquisite beauty of its colouring, 

 whose life-history is very remarkable, and which possesses the 

 additional interest of being the only living representative in 

 our seas of the group of organisms so familiar to us in the fossil 

 state as Encrinites. The delicate structure of this species 

 renders it impossible to preserve it satisfactorily in a dry state: 

 it is only when exhibited in some preservative fluid that any 

 idea can be formed of the elegance of the living animal. The 

 central cup-shaped body gives origin to five rays, which divide 

 so near the base as to appear like ten. These are furnished 

 throughout their length with membranous pinnae or fins, with 

 which the creature swims freely. It is said to propel itself 

 somewhat in the manner of a medusa, using its arms alternately, 

 five of them being in action while the other five are quiescent. 



In the year 1823, Mr. J. Yaughan Thompson (whose name 

 will be held in lasting remembrance as the discoverer likewise 

 of the metamorphoses of the Crustacea), found in the Cove of 

 Cork a creature about three-quarters of an inch in height, 

 resembling very much a minute feather-star set upon a flexible, 

 articulated stem. This he described and named Pentacrinus 

 Eurojpaius; but in 1836 he published a second paper in which 

 he announced his discovery that the Pentacrinus was but the 

 young state of Comatula, and this opinion is now held by all 

 zoologists. Mr. Thompson found all his Pentacrini attached to 

 Zoophytes, but they have been taken by others amongst Fuci, 

 though never upon stones or shells. The larger Comatulce are 

 mostly met with in deep water, being taken by the dredge ; 

 and it would appear that they come into the shallower water 

 near shore for the purpose of depositing their ova in the littoral 

 groves of Zoophytes and Laminarias. The development of the 

 animal from the ovum, through the pentacrinoid stage to the 

 mature form of Comatula, has never, I believe, been watched 

 uninterruptedly: the feather-star has not yet been caught in the 

 very act of leaving its cncrinital stem, but for all that, the facts 

 which have been observed, though they rather invite than 

 preclude further investigation, are amply sufficient to place 

 this most interesting episode of animal life beyond the doubt 

 of any but the most inveterate sceptic. 



