92 PALEONTOLOGY OF ILLINOIS. 



first nearly quadrangular, about twice as wide as high, the 

 second narrower, angular above, and supporting the first divi- 

 sion of the rays. 



Whether a second bifurcation takes place above this cannot be 

 determined from the specimen in hand, but one arm is preserved 

 to the ninth plate without division. Anal series unknown. 



Column composed of thin circular plates, with a, thicker one 

 intei'ealated at intervals of six to eight plates below its summit. 



The only example of this species \ve have seen is too much 

 crushed for a complete diagnosis to be given, but its mamillate 

 form, and long under-basals, will serve to distinguish it from any 

 species known from this horizon. 



Position and locality: Warsaw beds of the St. Louis forma- 

 tion, Warsaw, Illinois. 



Collector, A. H. Worthen. 



No. 2."i78 of the Illinois Stale Museum. 



(iK\rs CALCKOCRTNUS. Hall. 

 CALCEOCRINUS ROBUSTTS. (sp. nov.) 



PI. XII, Fig. 7. 



Calyx subqnadrate with the upper lateral angles truncated 

 and sides constricted. Basal plate triangular, about three times 

 as wide as high. Lower dorsal plate triangular, .of about the 

 same width as the basal, and beveled below to fit the basal 

 plate. Dorso-lateral pieces twice as wide as high, with the upper 

 inner angles truncated for the reception of the succeeding plate. 

 Upper dorsal plate triangular, about once and a half as wide as 

 high, and slightly rounded at the lateral angles. 



Dorsal arm robust, composed of six stout first radial plates, 

 the upper of which is axillary, giving support to the secondary 

 series of which there are three, the upper one an axillary plate 

 supporting the arms. The outer division continues single while 

 the inner one divides on the third or fourth plate, giving six 

 arms to this ray. 



Lateral rays five, four of which are nearly equal in size, the 

 fifth quite small, and not preserved beyond the first bifurcation. 

 The first radial plate in the lateral rays is twice as long as wide, 

 that of the first lateral resting obliquely on the excavated outer 



