Ilf THE MORPHOLOGY OF THE CYSTIDEA, 33 



more remarkable from the fact that they are so largely developed 

 in the Cystids, iu many of which, e. g. Pseudocrinus and Callo- 

 cystis, the lateral appendages of the ambulacra seem to have been 

 of the same nature as the so-called pinnules of the Blastoids, 

 though less numerous and more highly developed. I have the 

 very strongest conviction that the basal and radial plates, and 

 probably also the dorsocentral, constitute a fundamental part of 

 the organization of every Echinoderm, except, perhaps, theHolo- 

 thurians. They have not as yet been identified in any members 

 of this class ; but I think it by no means improbable that they 

 might be found to have the same relation to the right enterocoel 

 in the larvse of the heavily-plated Psolidse, as they have in other 

 Echinoderms. 



It is now some years since the publication of Loven's classical 

 studies of the apical system of the IJrchius *, and his comparison of 

 it with that of a Crinoid. In the words of the cousins Sarasinf : — 



" In dem ganzen so vor Durclibrucb des Afters von elf Flatten bedectten 

 Apicalpol sak nun Loven die Hauptziige einer Bauart, welcbe man bis dahin als 

 dem Echinidentypus nielit zugehorig, sondern als cbaracteristisch fur den Cri- 

 noidentypus betrachtete, und er benutzte dies zu einem Versuche, die Echiniden 

 von den Crinoiden abzuleiten." 



The Sarasins speak of this appearance as the " Crinoidenfan- 

 tom der Echiniden," referring to me as one of its " emsigsten 

 Verfolger ; " and they bring a variety of arguments against a 

 Crinoid ancestry for the Urchins, while they endeavour themselves 

 to prove that all the classes of Echinoderms are derived, directly 

 or indirectly, from the Holothurians. 



It seems to me, however, that the so-called " Crinoidenfantom " 

 is one of the Sarasins' own making, and tiaat they have completely 

 misapprehended the position of Loven and myself. They do not 

 refer to a single passage in Loven's writings which indicates that 

 he regards the Crinoids as in any way the ancestors of theEchinids. 

 He did say, however J : — " Dans I'une et 1' autre de ces grandes 

 classes d'Echinodermes le systeme dorsocentral, se presentant 

 sous des aspects divers, est done identique dans ses traits prin- 

 cijDaux de conformation." Earther on in the same volume he 

 pointed out that the dorsocentral system of a young Asterid is 



* " Etudes sur les Ecbinoidees," K. Svensk.Vetensk. Akad. Handl. 1874, Ed. xi 

 No. 7, pp. 65-91. 



t Op. cit. p. 142. \ hoc, cit. p. 72.. 



\jTSS. JOUllX. — ZOOLOGY, TOL. XXIT. 3 



