30 



Turning now to the posterior side, we find on the right a small 

 intercalated triangular plate, and a brachial series of three plates 

 resting upon the right side of the triangular basal and this inter- 

 calated triangular plate. This brachial series reaches about as 

 high as the other brachial series, the last plate is axillary and 

 bears free arms. Every second or third plate in these free arms 

 is axillary, though one of the rays thrown off from each axillary 

 plate is smaller than the main arm and does not bifurcate again. 

 On the left of the posterior side we also find a small intercalated 

 triangular plate, and a longitudinal azygous series resting on the 

 left side of the triangular basal and this intercalated triangular 

 plate. The azygous series consists of three large round plates, 

 having a width more than twice as great as their length, and they 

 are followed by a long round proboscis that extends beyond the 

 limit of our broken specimens and probably beyond the length of 

 the arms. The three azygous plates reach about as high as the 

 brachials above described and in comparing with other crinoids 

 this would be the limit of the calyx, and above this are the free 

 arms and long proboscis. It will be understood that we have de- 

 scribed this species as if it were standing up instead of hanging 

 down from the end of the column. 



It is unnecessary to compare this species with any others that 

 have been described, though it is doubtless congeneric with the 

 species described by W. R. Billings, and for which Ringueberg 

 has described a genus under the name of Castocrinus. Probably, 

 without hesitation it should be called Castocrinus kentuckiensis. 

 But there has been so much blundering and bad work done with 

 the Calceocrinidae and so many synonyms proposed, that we have 

 thought, without taking the time now to review the subject, it 

 would be sufficient to provisionally refer it to Calceoerinus, though 

 we think, at present, that Castocrinus will be retained for this 

 generic division of the family. 



Found in the Trenton Group, in Mercer county, Kentucky, and 

 now in the collection of Win. F. E. Gurley. 



