NOTES ON ECHINODERM MORPHOLOGY. 



19 



The former always receive the same names, and the latter are 

 baptised according to circumstances. Why then should not 

 the plates which alternate with and support the radials of a 

 Crinoid always receive the same name, whether they rest 

 directly on the stem or not? The following table shows the 

 variety of designations which have been applied to the two sets 

 of plates beneath the radials of dicyelic Crinoids since the 

 time of Miiller. 





As if this question of nomenclature were not sufficiently 

 complicated already, a further change has been proposed bv 

 Trautsehold,^ who wishes to call the subradial plates of 

 dicyelic Crinoids " supra-basals." His reasons are that the 

 " Basis ^^ of the monocyclic forms consists of but one ring of 

 plates; for while "bei den dicyclischen die zwei unteren Tafel- 

 kranze die Basis bilden, so sind die Flatten beider gleich- 

 werthig, und die Flatten der ersten wie der zweiten Basis sind 

 ^. basalia oder Basalplatten, sie sind integrirende Theile der 



monocyclischen Basis sowohl wie der dicyclischen." 



The question here turns on the use of the term "Basis," which 

 Trautsehold interprets as meaning all plates between the 

 radials and the top stem-joint; and in this sense there is an 

 undeniable equivalency between the single and double sets of 

 subradial plates in the two forms of calyx. But the dicyelic 



' " Ueher die Bezeiclinung der Kelchplattea der Crinoideen," ' Bull. See. 

 imp. des Nat. de Moscou,' Tom. Ivii, 1882, No. 3 (1883), pp. 201—203. 



