

Miscellaneous. 387 



there may be some doubt as to whether it is a fully developed 

 animal or only a stage of development. The three spines at the 

 apex of the arms are to be found, although not of the same size, in 

 very young examples of many species of the family Astropectinidae. 

 In many species of the same family, especially when young, there 

 is also a very small conical protuberance in the centre of the disk ; 

 but on comparing such young animals of about the same size as 

 Ilyaster, they find that these peculiarities are of such a nature that 

 they can scarcely change in any essential degree with age ; and 

 therefore they have felt compelled to form a new genus for the pre- 

 sent species. 



When alive, Ilyaster carries the central dorsal appendage pretty 

 nearly erect ; but it moved in small curves, and appeared as if it 

 might have been a ruptured peduncle, by which the animal had been 

 attached. If it be really the remains of such a peduncle, this must 

 have undergone some alteration after the animal became free, as is 

 shown by the form of the free end of the appendage. 



At the first glance it seemed that Ilyaster might possibly be a 

 young example of Bathyhiaster pallidas, with which it agrees in 

 many points ; but this notion has to be given up on comparing young 

 specimens of Bathyhiaster with Ilyaster. The latter has nopedicel- 

 lariae ; and where Bathyhiaster has the largo peculiar pcdicellariae, 

 along the ventral grooves, Ilyaster has a very large spine. Ilyaster 

 has four strong teeth, while young examples of Bathyhiaster have 

 no teeth, and adult animals only two. 



The examination of the small conical prominence of the middle 

 of the disk, which occurs in many species of the Astropectinidae. 

 shows that it has the same covering of paxillae as the rest of the 

 back of the disk. It is somewhat otherwise with the appendage in 

 Ilyaster. Here the covering is different from that of the disk ; so 

 that although we may be inclined to regard the appendix morpholo- 

 gically as a higher development of the above-mentioned small conical 

 knot, it has, at any rate, undergone alterations which cause Ilyaster 

 to differ in appearance from all other known starfishes But the 

 notion that the central conical process of the Astropectinida) is a 

 residue of a former peduncle by which the animal was attached 

 becomes greatly strengthened by our acquaintance with the dorsal 

 appendage of Ilyaster, which undoubtedly points towards the em- 

 bryonic stage of the Crinoidea. It seems very probable that ilyaster 

 has such a larval stage, and that even when free it will always bear 

 recognizable traces of this earliest period of its existence. If so, we 

 have to do with an extremely interesting phylogenetic phenomenon, 

 namely that the Starfishes have been developed from the Crinoids. 



In a supplementary note the authors refer to M, E. Perrier's 

 description of his Caidaster pedunculatus, a translation of which 

 appeared in this Journal for February last (p. 151). 



They also describe a new species of Echinus under the name of 

 E. Alexandria and discuss at some length the characters of the fol- 

 lowing species — Pedicellaster ty picas, M. Sars (with which they 

 combine Sladen's P. palteocrystcdlus), and Korethraster ty picas and 



