699 DR. W. B. CAEPENTEE ON THE STEUCTUEE, PHYSIOLOGY, AND 



Habits. 



9. Tho usual habitat of Antedon rosacetis appears to be water of from ten to twenty 

 fathoms' depth ; though it is found sometimes in shallower, and sometimes in deeper water. 

 My experience agrees with that of Professor E. Forbes, that the largest specimens are 

 obtained from deep water. The animals are generally brought up by the dredge either 

 actually clinging to Sea-weeds (usually Laminaria) or to Zoophytes or Polyzoa, or in 

 such association with them as suggests the idea that their detachment has been effected 

 in the act of diedging. For reasons I shall presently give, 1 cannot by any means assent 

 to the statement of Mr. J. V. Thompsox', that "this curious Star-fish is an animal not 

 only free, but leading the most vagrant life of any of the tribe with which it has been 

 hitherto associated by naturalists, — at one time crawling about amongst submarine 

 plants, at others floating to and fro, adhering to thin fragments by means of its dorsal 

 claspers, or even swimming about after the manner of the Medusa;." It is quite true 

 that, as stated by Mr. J. V. Thompson, and confirmed by Professor Edward Forbes, an 

 Antedon placed freely in water will swim with considerable activity, moving back foremost 

 by advancing five arms at a time, and then the alternate five ; in fact I do not know any 

 animal of which the movements are more graceful than those of the " feather-star " (as 

 Professor Edward Forbes appropriately called it). But 1 am quite satisfied from repeated 

 observations that these movements are not habitual to the animal, and are to be regarded 

 only in the light of a restless search after a new attachment, being kept up no longer 

 than is requisite for obtaining this. If an Antedon be placed in a large basin of sea- 

 water, having smooth sides and not containing any object of Avhich its dorsal ciiThi can 

 lay hold, the swimming action may continue (with occasional intermissions) for several 

 hours. But if a rough angular stone, a Sea-weed, a Zoophyte, a cluster of Serpula?, or 

 anything to which its dorsal cirrhi can attach themselves (Plate XXXI.) be placed in the 

 basin, the Antedon settles itself upon this, and if the attachment proves suitable, the 

 creature seldom changes it. I have kept a number of Antedons, without any other 

 animals, in the same Vivarium for several weeks together ; and I have observed that the 

 places of individuals which I could distinguish by some peculiarity of colour, were scarcely 

 at all altered during the whole period, — the amount of change, in fact, being little more 

 than would have been exhibited by an equal number of Actiniae. One fine specimen I 

 particularly noted as having firmly attached itself by the grasp of its dorsal cirrhi to the 

 tube of a Serpula ; and this it did not let go during the whole time of its captivity. 



10. Thus, as regards the ordinarj^ fixedness of its position, the condition of the adult 

 Antedon only difiers from that of its Pentacrinoid larva in this ; that whereas the latter 

 necessarily remains fixed to the spot to which the base of its pedicle was originally 

 attached, the former can quit its hold when its attachment is no longer suitable to its 

 requirements, and can move from place to place in search of another. How intimate, 

 moreover, is the functional relation between the dorsal cirrhi of the adult Antedon, and 

 the stem of its Pentacrinoid larva, further appears from the fact that the cirrhi only 



' Edinb. Xew Philos. Journal, vol. xx. (1835-36) p. 296. 



