658 THE CRINOIDEA CAMEEATA OF NORTH AMERICA. 



gently upward to meet the radials. Radials as wide as long, one fourth 

 wider near the top than at the bottom ; facets very large, occupying more 

 than a third the width of the plates, and reaching down to almost one half 

 their length ; they are directed obliquely upwards, subcircular, and but 

 slightly notched at the upper end ; the surface concave, and perfectly 

 smooth. The limbs of the radials bend a little inward, their upper faces 

 abruptly truncated ; they support three rather small interradial plates, of 

 which the outer ones face the costals, and are in part interambulacral. 



Horizon and Locality. — Base of the Lower Burlington lime.stone ; Bur- 

 lington, Iowa. 



Types in the collection of Mr. R. R. Rowley of Louisiana, Mo. 



Platycrinus sequiternus S. A. Miller. 

 Plate LXXI. Fig. 1%. 



1891. S. A. MiLLEB; Bull. 4, Geol. Surv. Missouri, p. 14, Plate 1, Fig. 13. 



Syn. Platycrinus curryviUensis Rotvley and HiBE, 1891 ; Kansas City Scientist, p. 98, Plate 2, 

 Fig. 5. 



A moderately small species of the type of P. pileiformis Hall ; described 

 from the basals and radials only. Dorsal cup to the top of the radials obcon- 

 ical, as wide as high, truncated below, the sides very little convex ; cross- 

 section somewhat quinquelobate. Plates flat and without ornamentation ; 

 suture lines not grooved and rather obscure. 



Basals closely anchylosed, forming a truncated, rapidly expanding basin, 

 equal in height to half the length of the radials; the lower face sufficiently 

 depressed to contain the proximal stem joint, which is circular and slightly 

 serrated around the edge. Radials longer than wide, gradually expanding, 

 convex longitudinally, the convexity increasing toward the facets ; the slop- 

 ing upper faces toward the anal side deeper, and forming a broader notch ; 

 the facets of the two posterior radials pushed to one side. Facets semi- 

 ovoid, slightly concave, the upper edge a little excavated ; they occupy half 

 the width of the plates, and nearly one third their length, project abruptly 

 outward, and face laterally. 



Horizon and Locality. — Chouteau limestone ; Sedalia, Mo. 



Ty2:}e in the collection of Mr. F. A. Sampson, Sedalia. 



