92 OWEN AND SHUMARD'S FOSSIL CRINOIDEA. 



eight to ten. The superior ones are spinous, and each supports two fingers, one of 

 which continues without further division to the summit, the other bifurcates several 

 joints above its origin. 



Proboscis long and slender, surmounted by three plates of a conical figure, joined 

 too-ether at their bases. 



Column unknown. 



The specimen figured was obtained from the archimedal layers of the carboniferous 

 limestone of Kaskaskia, Illinois. It there occurs with Terebratula plano-sulcata, 

 T. Roissyii, Peniremites florealis, P. pijriformis, P. Cherokeus, (Troost,) and 

 Poteriocrinus {Zeacrinus) magnoUaformis, (Troost.) It occurs also in a similar 

 geological position in Grayson Co., Kentucky, where it was discovered by Dr. L. P. 

 Yandell, whose fine collection of crinoids contains a very perfect specimen of this 

 interesting species. 



Poteriocrinus occidentalis. (New sp.) 

 PI. XL fig. 5, a, h. 



Calyx. — Cup-shaped, increasing from the base to the summit, swelled in the 

 middle; transverse section nearly circular ; plates somewhat massive, smooth, slightly 

 convex. First series of plates five, irregularly pentagonal, closely adhering among 

 themselves, bent upwards below to form the sides of a funnel-shaped cavity, at the 

 bottom of which is situated the basal plate; inferior edge very short, lateral edges 

 straight; superior angles obtuse; in their connection they form a pentagon with 

 straight or slightly concave edges. Second series five, longer than wide, and more 

 than double the size of those of the first series, smooth, moderately convex ; three are 

 pentagonal, and two irregular and hexagonal, resting by their edges on the superior 

 edges of the first series. Superior plates pentagonal, short, width about double the 

 length ; inferior angles obtuse ; lateral edges straight, superior edges slightly concave ; 

 facets for the arms nearly equal to the entire width of the plates. Accessory pieces 

 three, irregular, one oblong quadrangular, two sub-pentagonal. The quadrangular 

 plate is larger than the rest, and its superior angle is truncated to support one of the 

 smaller accessory pieces. A few joints of the arms are preserved in the only specimen 

 we have found of this species, viz. : a single brachial piece, which is pentagonal and 

 slightly arcuated on the lateral edges; on its oblique upper edges rests the 

 commencement of a double series of hand joints, consisting of wedge-shaped pieces. 



The column has not been discovered ; judging, however, from the small impression 

 on the calyx, it must have been very slender in comparison with the size of the body. 



It occurs at Chester, Illinois, where it occupies a similar geological position as the 

 preceding species. 



