Morphology o/'Antedon rosacea. 25 



Singularly enough, however, both these reviews and the 

 volume which suggested them appear to have been altogether 

 unknown to Messrs. Vogt and Yung ; for the * Challenger ' 

 Report is not mentioned in the bibliography of the Crinoidea 

 which appeared in the autumn of 1886, eighteen months 

 after its publication * ; and on p. 571 they say with 

 reference to the Stalked Crinoids that " les seuls travaux 

 detailles sur I'anatomie sont : celui deja ancien de J. Miiller 

 sur le Pentacrinus caput Medusce de la mer des Antilles, et 

 celui plus moderne de M. H. Ludwig sur la Rhizocrinus lofo- 

 tetisis.^' Continuing their comparison of the Stalked Crinoids 

 with the typical Comatula, they say : — 



" II rdsulte de ces travaux que les organes du disque, des 

 bras et des pinnules sont disposes en general, sur le type des 



Comatules En revanche^ il y a des conformations con- 



servSes qui ne sont que passagh'es dans la larve pentacrinoide 

 des Comatules. II n^y a qiCun seul pore calycaire^ reuni par 

 un sac a un seul tube hydrophore''' And after giving other 

 details of the resemblances between the adult Pentacrinus or 

 Rhizocrinus and the Comatula larva, tliey add : — " C'est un 

 des plus beaux exemples de la conservation de caract^res 

 embryonnaires dans des animaux adultes." 



Now, although the authors do not state the fact in so many 

 words, they certainly imply that in the Stalked Crinoids, as 

 known from the researches of Miiller and Ludwig, there is 

 only one water-pore and only one '^ tube hydrophore," just 

 as in a certain stage of the Comatula larva. I do not know 

 what other meaning can be attributed to the passage which I 

 have italicized. But, according to the descriptions of Pro- 

 fessor Perriert, the developmental stage of Comatula in which 

 only one water-pore is present is the " phase de Cystidd," 

 in Avhich the arms are not developed. These do not appear till 

 the " phase de Peutacrine," when there are five water-pores, 

 one in each interradius j and as Ludwig's observations show 

 that this condition is permanent in Rhizocrinus IqfotensiSj 

 Messrs. Vogt and Yung would have done better to refer to this 

 later developmental stage rather than to the pre-brachial 

 " Cystid phase " as an illustration of the " conservation des 

 caract^res embryonnaires dans des animaux adultes." 



\YiIl they name a single Stalked Crinoid which resembles 

 the Cystid pliase of Antedon in having but one water-pore 

 and water-tube ? Do they not know that there are never less 



• It may be well to state liere that I was iiuable to obtain Livraison 8 

 of the ' Traits,' which coutaius the bibliography of the Criuoidea, tiU 

 Oct. 25, 188(3. 



t ' Comptes Rendus,' 1884, t. xcviii. pp. 444, 445. 



