REPORT ON THE CRINOIDEA. 399 



I'avons etabli, des plaques dorsales disposees au debut, comme celles du calice des 

 Crinoides ; nous avons demontre que, chez les Brisinga, les plaques de la premiere rang^e 

 deviennent les odoutopliores." Even yet, however, no figures of the various develop- 

 mental stages of Brisinga have been published in " demonstration " of Perrier's 

 statements, which were summarised as follows, " Ainsi les odontophores sont les rcstes 

 des pieces du premier rang du disque primitif de la Brisinga. L'identitd dvidente du 

 plan d'organisation des Brisinga et des Asteries proprement dites rend la meme conclu- 

 sion probable pour les autres Etoiles de mer." It is undoubtedly probable that what is 

 true of Brisinga also applies to all the other Asterids ; and it is therefore the more 

 desirable that some proof should be offered of the very definite statements made by 

 Perrier. They have recently been disputed by Sladen ^ on the ground that in all the 

 Starfishes of which the embryonic stages are sufficiently known, the basals and odonto- 

 phores are " separate and distinct, and co-exist independently from their first formation ; " 

 while he further expresses his belief, based on sound morphological arguments, that the 

 origin assigned by Perrier to the odontophoi'es of an Asterid is theoretically impossible. 



Perrier has recently repeated his statements in somewhat greater detail," and having 

 compared Loven's figures of the young Asterias glacialis with his young specimens of 

 Brisinga, he says that he has no doubt whatever, "que les choses se passent de la mSme 

 facon dans les deux genres, et nous pouvons, dfes lors, affirmer que les pieces radiales {sic) 

 des tres jeunes AsteriadfB deviennent dans cette ordre de Stellerides les odontophores." 



Unfortunately for his theory, however, these interradial abactiual plates of the 

 young Asterias develop in other Starfishes into relatively large plates which remain in 

 more or less close relation with the dorsocentral, and are the very plates described as 

 basals by Sladen not only in the larval Asteiias, but also in the following genera — 

 Zoroaster,'^ Pentagonaster, Tosia, Astrogonium, Stellaster, Nectria, Ferdina, Pentaceros, 

 Gymnasteria, and others. 



As there is an odontophore on the ventral side in each of these types, it is perfectly 



' Q%mrt. Joum. Micr. Sci, 1884, vol. xxiv., N. S., p. 39. 



2 Memoire sur les Etoiles de Mer recueillies clans la mer des Antilles et le Golfe du Mexique durant les expeditions 

 de dragage faites sous la direction de M. Alexandre Agassiz, Nouv. Arcliiv. du Mus. cVHist. Nat, S"" ser., 1884, t. vi. p. 159. 



3 Several months before the appearance of Perrier's Eeport upon the AVest Indian Starfishes, Sladen figured the 

 apical system of Zoroaster fidgens, and described it in the following terms : "Surrounding a dorsocentral and five small 

 radially placed plates are five large plates iutemulial in position ; and outside and alternating with these are five 

 similar but rather smaller radially placed plates. ... It will be noted that these plates represent in a remarkable manner 

 the dorsocentral, the under-basals, the basals, and the radials respectively of the Crinoid calyx " (Asteroidea dredged in 

 the Faroe Channel during the cruise of H.M.S. " Triton " in August 1882, Trans. Roy. Soc. Edin., vol. xxxii. p. 160, 

 figs. 9, 11). Precisely the same arrangement appears in the apical system of Zoroaster acMeyi, so far as one can judge 

 from Perrier's figure of an entire specimen (Nouv. Archiv. du il/its. d'Hist. Nat., 2™" ser., 1884, t. vi. pi. iii. fig. 1); but he 

 makes no mention of Zoroaster fulyens. Even if he had not seen Sladen's reference to it, one would have thought that 

 he would have been struck liy the Crinoidal aspect of Zoroaster ackleyi, though he does not refer to it at all, and he 

 gives no detailed description of the plates. It would be interesting to know his reasons for believing that the large 

 interradial plates in the immediate neighljourhood of the dorsocentral are not the " plaques de la premiere rang(5e " 

 of the larva, which occupy exactly the same position with reference to the dorsocentral, and are believed by Perrier 

 to become the odontophores in all Starfishes except Caulaster. 



