ECHINODERMA TA—CRINOIDEA . 



535 



cup, plates of dorsal cup less convex and anal area more tumid, 

 protruding abruptly. (Type of genus.) 



Keokuk of Kentucky, Tennessee and Missouri. 



114. A. tuberosus Hall. (Figs. 1862, 1863.) Mississippic. 

 First IB short and scarcely visible in side view. 



Keokuk of Tennessee, Illinois and Iowa. 



115. A. coreyi Lyon and Casseday. Mississippic. 

 Dorsal cup high for the genus, but somewhat lower than the ven- 



•V 



Fk,. 1S63. Agaiicocrinus tuberosus, o^^o?>\i& views. 

 (After Hall, Iowa GeoL, I., 2.) 



tral disk. Plates elevated, smooth. Anus at end of an elongate 



Keokuk of Kentucky and Indiana. 



1 1 6. A. crassus Wetherby. Mississippic. 

 Larger than A. tuberosus, distinctly pentalobate, depressed con- 

 vex with but slightly concave base and with rays of two arms each 

 except the two posterior which have three or four. 



Keokuk of Kentucky, Tennessee, Indiana and Iowa. 



117. A. nodulosus Worthen. Mississippic. 

 Distinguished by the greater number of arms, four each to two 



of the rays, three each to two rays, and two to the anterior ray. 

 Keokuk of Tennessee, Indiana, Illinois and Iowa. 



118. A. splendens S. A. Miller. Mississippic, 

 Smallest of the Keokuk species. Calyx distinctly five-lobed, 



owing to the prominent arm facets. First IB elongate, rising to the 

 middle of the second costals. Plates of dorsal cup flat. Orals all 



