CRINOIDEA. 



269 



column is a series of plates which are termed " basal " from 

 their position, and which constitute the " pelvis " of Miller. 

 The " basal s " may be five, four, three, or rarely two in num- 

 ber, and they form the lowest portion of the cup. In general 

 the basals are free, and are simply articulated by their edges, 

 but in some cases it is believed that they are more or 

 less undistinguishably fused with one another into a single 

 mass. In many cases the " basals " are succeeded by a 



Fig. 158. Diagram to show the structure of the calyx in the fossil Crinoicls. b, Basals ; r, 

 Uadials ; i. Inter-radial s ; a, Anal plates. Calyx of Forbesiocrinus. After De Koninck and 

 Le Hon. (As it has now been discovered that this genus really possesses three small basals, 

 below the plates here represented, the pieces lettered b are truly "parabasals.") 



second row or cycle of plates, which may be regarded, with 

 Professor Beyrich, as a second series of basals, but which are 

 properly regarded as something special, and are termed the 

 "parabasals" or " sub-radial s." The basals (fig. 158, b) are 



comprehend. To this cause of confusion must be added the fact that different 

 observers have employed the same terms for parts which do not appear to be 

 truly homologous. In the present state of uncertainty upon the whole of this 

 subject, it has seemed sufficient to give here merely a general account of the 

 nomenclature which has hitherto been most generally employed in works 

 descriptive of the fossil Crinoids, though this nomenclature is probably often 

 not strictly correct. 



