57 
Damit fållt auch der Boden fiir die Detailparallelisirung einzelner 
Plattengruppen am Echinidenscheitel und Crinoidenkelch und damit 
iiberhaupt jede nahe Homologie zwischen Crinoiden und Seeigeln 
weg; vom palæontologischen Standpunkt liegt kein Ankaltspunkt 
fiir die Annahme einer engen Beziehung zwischen beiden Classen 
vor, sie ersckeinen im Gegentheil als die aussersten Extreme im 
ganzen Eormengebiet der fossil naher bekannten Echinodermen“. 
Upon the whole, the necessary condition for tracing a homo¬ 
logy between the apical system of Echinoids and the calycinal 
system of Crinoids must be the existence of this configuration of 
plates in the supposed common ancestor of Crinoids and Echinoids, 
and the same, of course, holds goods for the alleged homology of 
the Crinoid calyx with the apical plates of Asteroids and Ophiurids. 
But these plates were not thus developed in the forms from which 
we must suppose that the Crinoids on one side and the Echinoids, 
Asteroids and Ophiurids on the other side have originated. I may 
quote from Dr. Bather 1 ) the following passage: „What is fatal 
(to the theory of the homology between these plates) is the con- 
clusion to which the evidence of fossils forces us — that the free 
Echinoderms, if they arose from stalked forms at all, indubitably 
did so ages before a calycinal system had been evolved . . . . 
If, however, it be impossible to regard the apical systems of 
Echinoidea and Asteroidea as homogenetic with that of Crinoidea, 
there can be no objection to the statement that similar plates 
are developed in a similar position with regard to the fundamental 
anatomy, under the intluence of somewhat similar causes“. — With 
this I fully agree. 
*) A Treatise on Zoology. Ed. by E. Kay Lankester. Part. III 
Echinoderms, p. 14. 
