THE STELLERO1DEA 



269 



below each radial. The genus in which these supposed calycinal 

 plates most resemble a Crinoid cup is the genus Ophiopyrgus 



Via. XX lit. 



Abactinal plates of Ophioccrmnis olmtrii-ta, Lyin. (after Lymau). c, central plate ; r.it, radial 

 shields ; il.a.p and l.a.p, dorsal and lateral nnu-|>lntes. 



(Fig. XXV.), in which the dorsal side is raised into a conical 

 projection. 



The irregularity of these " calycinal plates " both in develop- 



FI.I. XXIV. 

 Abactinal plates of disc of Ojthiwa inornata (Lain.), c, central, r.n, radial shields. 



ment and arrangement discredits their supposed homology with 

 the three circlets of plates in the calyx of a Crinoid. It is only 

 natural that among the many variations in the grouping of the 



