646 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 



which the two genera can be separated in the fossil state. Endadocrinus is 

 an extravagantly developed Platycrinus, and should perhaps be regarded as 

 a subgenus. 



Coccocrinus was placed by Miiller and Eoemer among the Platycrinidse ; 

 by Pictet, Dujardin and Hope, Zittel, and S. A. Miller, under the Haplo- 

 crinidEe ; while at the same time the latter authors refer the closely allied 

 CuUcocrimcs to the Platycrinid^, which according to our classification would 

 place the one among the Larviformia and the other among the Camerata. 

 We do not see how this can possibly be the case ; we believe that Cocco- 

 crinus is a true Camerate Crinoid, which passed the Larviformia stage in early 

 life on the introduction of perisomic plates. The genus holds a similar re- 

 lation morphologically toward Platycrinus to that of the recent genus Holo- 

 pus toward Hyocrinus, whose orals have been carried inward by increased 

 perisome. 



In Part II. of the Revision we referred the doubtful genus Cotykdono- 

 crinus to the Platycrinid^, but have since found it to be identical with 

 Dicliociinus. 



In descriptions of the Platycrinidse and Hexacrinidse we sometimes use 

 the term " interradials " for the lowest plates between the rays, because, as 

 already stated, they are neither exclusively interbrachial nor interambulacral, 

 but partake of the character of both ; that is, the same plate often belongs 

 partly to the dorsal cup and partly to the tegmen. 



