18 



The vault is conoidal and about as large as the calyx. It is 

 covered with smooth, polygonal plates and bears a long, small 

 central proboscis. 



This species is distinguished by the smooth plates of both 

 the calyx and vault, by the sixteen ambulacral openings, with 

 a formula of 34-4-f-~-f-4-f 3, and thirty- two arms. It is further 

 distinguished by the six plates in the azygous area. Only three 

 species have been, heretofore, described from the Keokuk 

 Group with thirty-two arms, and none of them resemble this 

 one. There have been fifteen species described from the Keokuk 

 Group with sixteen arms and possibly one or two of these have 

 thirty two arms, but they are ornamented species bearing radial 

 ridges and have little resemblance to this one. It is unneces 

 sary to make any comparison with any other species. 



Pound in the Keokuk Group, at Boonville, Missouri, and the 

 specimen having the arms with other specimens are in the 

 collection of Wm. P. E. Gurley, and the one showing the vault 

 and others are in the collection of S. A. Miller. It preserves 

 part of the arms opposite to the side illustrated. 



Remarks.— The arms flatten as they approach the superior, 

 ends and when they curve in or infold toward the vault they 

 become longitudinally concave in all the specimens. This is 

 another illustration of the futility of undertaking to establish 

 genera on the character of the arms, for if you can do so, this 

 would belong to Eretmocrinus or to a new genus, according to 

 the taste of the author. 



BATOCRI&US FABERI, 11. sp. 



f late II, Fig. 3, azygous side; Fig. 4, opposite view. 



..Body rather below medium size "and somewhat biturbinate or 

 wheel- shaped, though the calyx is decidedly larger than the 

 vault. Calyx truncated below and slowly expanding to the 

 third radials and then abruptly spreading to the free arms. 

 Arm openings directed horizontally. Twice as wide as high. 

 No .radial ridges. Plates slightly convex in the superior part 

 and tumid below. Surface granular. 



Basals short and form a low subhexagonal disc, with slight re- 

 entering angles. The disc is about one -fourth wider than the 

 diameter of the column and bears a shallow concave depres- 



