ECHINODERMATA—CRINOIDEA. 



531 



102. E. coronatus (Hall). Mississippic. 

 Distinguished by the coronate aspect of the tegmen, due to the 



upward and outward extension of the spines around the periphery. 

 Lower Burlington of Missouri and Iowa. 



103. E. leucosia (Hall). Mississippic. 

 Calyx broadly spindle-shaped. Sides of dorsal cup straight or 



only slightly concave. Plates moderately convex, unornamented. 

 Lower Burlington of Missouri and Iowa. 



104. E. magnificus Lyon and Casseday. Mississippic. 

 Calyx spindle-shaped, with dorsal cup often shorter than the 



high, conical tegmen, and with concave sides. R and brachials 

 convex to keel-shaped; interbrachials flat. 



Keokuk of Kentucky, Tennessee and Indiana. 



XLI. DoRYCRiNUS Roemer. 

 Calyx broadly turbinate or subglobose, truncate at base, and 

 deeply sinuate in all the interradial areas, but chiefly so in the 

 posterior one. B 3, large, produced below into a conspicuous rim. 

 R usually as large as the two costals together. Distichals two, 

 or one when followed by a row of palmars. Plates of the dorsal 

 cup smooth or corrugated, frequently nodose, but not striated, 

 and all more or less convex. Arms in pairs, two to four pairs to 



Fig. 1858. Dorycrinus unicornis^ three views of the same individual. 

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



a ray, short and spinose. Tegmen strongly convex, composed of 

 moderately heavy plates. Orals five, large, the posterior one fre- 

 quently extended into a long spine and occupying a central posi- 

 tion. Surrounding the orals and overlying the ambulacra are 



