THE STELLEROIDEA 



269 



below each radial. The genus in which these supposed calycinal 

 plates most resemble a Crinoid cup is the genus Ophiopyrgus 



Via. XXIII. 



Abactiiutl platt-s of Ojihiw )< is t>itr'u-tii, Lyin. (after Lyinan). c, central plate; r.s, radial 

 shields ; tl.u.p and l.a.p, dorsal and lateral ami-plates. 



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

 projection. 



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



Ki.;. XXIV. 

 Abactinal plates of ilisc of Ophiimi in<>rn<it<( (Lain.)- c, central, /..<, railial 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 



