Descriptions of New Species of Crinoids. 137 



the arms were long eaough to rejieh to the center of the depression at 

 the base of the raj-s, which space is filled, as may be seen in the figure 

 of the type, hy a Gasteropod, »vhich rests upon the top of the vault, 

 hiding its cap-piece, of which the form is unknown. 



Interhrachial Rays — Five, very wide, much thickened, somewhat 

 convex above, more so below, and widely bifurcate at the extremities. 

 As will be seen in the figure, these divisions from opposite rays reach 

 and even over-lap each other. It is clearly shown in the type, and in 

 fragmentar}' specimens, that the rays are articulated to the vault alone, 

 and not to the body plates. They are, as was first suggested by Meek 

 and Worthen (Geo. Sur. 111. vol. ii., p. 290), true vault pieces, or at least 

 the}^ have no connection witii the other parts that can be determined 

 from the specimens studied, which are sufficient in numbers, and in 

 excellent preservation in most cases. In some of the species the weight 

 of these ra3^s exceeds that of all the other parts of the crinoid combined ; 

 in others they are very thin, light, and either narrow and long, or wide 

 (high) and comparatively short. 



Locality and position: Kaskaskia (Chester) Group, sub-carbon- 

 iferous, Pulaski county, Kentucky. 



All the species described in this paper were collected by me in the 

 sand}' shales, forming the upper part of this group, at the locality 

 above cited, and the types are a part of my cabinet of sub carbon- 

 iferous fossils. 



Pterotocrinus spaxulatds, nov. sp. 

 Plate XI., fig. 3a upper, 36 basal, 3c side view. 



Basals — Two, small, pentagonal, slightly elevated below, and ex- 

 cavated, centrally, on their line of junction, for the reception of the 

 slender column. The anal piece rests upon their angular excavation 

 on the azygos side, and the first radial upon the other. 



First radials — Five, having the form usual to the genus, wider than 

 high, all excavated centrally, for the reception of the small second 

 radials, which cover about one half their upper surface, leaving the 

 outer extremities exposed. 



The great width of these plates, in comparison with their height, 

 causes the flattened form of the cup characteristic of this species. 



Second radials — Ten, irregularly quadrangular, wider than high, 

 resting upon the upper central surface of the first radials, and covering 

 about one half this side of each. 



Third radials — Twenty, in groups of fours over the first radials, ir- 

 regularly quadrangular, wider than high, the central two of each 



