530 NORTH AMERICAN INDEX FOSSILS. 



XXXIX. Strotocrinus Meek and Worthen. 

 Large. Structure of calyx in general as in Actinocrinus, but 

 upper part of dorsal cup produced in an immense horizontal rim 

 mcorporating the lower parts of the arms and the lower pin- 

 nules. Rays of rim lo, each sometimes with 15 arms which are 

 given off alternately from opposite sides, each brachial support- 

 mg an arm and a higher brachial. Arms thin and short. Tegmen 



m %m 



'W 



Fig. 1857. Sh-otocrinns regalis, ventral (vault) and lateral vievrs of a 

 specimen, X %• (After Meek and Worthen. ) 



flat, composed of innumerable minute pieces. Anus excentric, 

 opening through the tegmen. Mississippic. 



loi. S. regalis (Hall). (Fig. 1857.) Mississippic. 



Plates of dorsal cup convex, covered with strong angular ridges 

 which rarely meet but usually leave a small smooth area in the 

 center of the plates. (Type of genus.) 



Upper Burlington of Missouri, Illinois and Iowa. 



XL. Eretmocrinus Lyon and Casseday. 



Resembles Batocrinus but the B project outward in a broad 

 rim, the arms are nearly twice as long, their upper portions much 

 wider, paddle-shaped, and folded inward ; the ventral disk is asym- 

 metrical, bulging anteriorly and flattened posteriorly, and the anal 

 tube is shorter, excentric, and often bent abruptly to one side. 



Burlington and Keokuk of America. ♦ 



