65. CONTRIBUTION TO 



AOROCRINUS CASSEDAYI. Lyon. Rowley. 



Plate 23. Figs. 4-5. 



The broad disk is greatlj^ expanded in this crinoid, recalling the rim in 

 some species of Eretmocrinus and some of the larger Dorycrini. 



All of the plates of the ealix are strongly nodose and deeply pitted at the 

 angles by -the radiate arrangement of the sculpturing. The arm lobes are strong 

 and separated by deep valleys, especially in a ventral view. There are four arm 

 bases to the lobe or twenty in all. The anal opening is located laterally and on 

 a distinct fold in the broad and deep depression above the anal interradial area, 

 strongly recalling a similar feature in the Dorycrini. The plates of the vault 

 are small, convex and the central one and the one at the junction of the 

 ambulacral ridges in each of the five radial series are highly nodose, almost 

 spinose. Wachsmuth and Springer who have given the only drawings of 

 complete bodies of this crinoid make no mention of these ray spines, neither do 

 they figure them. 



Hamilton group near Charlestown, Ind. Collection of Mr. G. K. Greene. 



AOROCRINUS CASSEDAYI Var. C H A RL E S T O W N EN S I S, 



N. Var. (Rowley) 



Plate 23. Fig. 6. 



Outside of the peculiar fluted appearance of the continued basal rim and the 

 more complete channeling of the calix plates by the radiate sculpturing, this 

 specimen, a calix only, differs little from our figures 4 and 5 of the plate. How- 

 ever, a complete body necessitate an entire specific separation. 



From the Hamilton group near Charlestown, Ind., and in the collection of 

 Mr. G. K. Greene. 



AOROCRINUS DEPRESSUS, N. Sp. (Rowley.) 



Plate 23. Fig. 7. 



The small basals, only seen a doral view of the calix, form a small hexagon. 

 The first radials are large and strongly nodose, with short ridges extending 

 to the second radials and the first interradials. The second radials small, 

 quadrangular, blunt, spinose. The bifurcated third radial, five sided and 

 forming a sharp elevated ridge. The double series of radials above this latter 

 consists of two plates each (higher plates being wanting in the specimen) and 

 so expanded as to leave but narrow interradial spaces, suggesting an almost 



