5o8 



NORTH AMERICAN INDEX FOSSILS. 



Fig. 1 82 1. Barycrinus hoveyi, X K- (After Meek and Worthen.] 



Fig. 1822 



Barycrinus ma^nijicus, side and 1 

 (After Meek and Worthen.) 



views, X Vz- 



Mississippic. 



33. B. hoveyi (Hall). (Fig. 1821.) 

 Arms slender, usually only two to a ray. 

 Keokuk of Indiana, Missouri and Iowa. 



34. B. magnificus Meek and Worthen. (Fig. 1822.) Mississippic. 

 Calyx large, bowl-shaped. Surface covered with small tubercles. 

 Keokuk of Illinois and Iowa. 



XV. PoTERiocRiNus Miller. 

 Calyx obconical. B 5, high, with five IB which are sometimes 

 hidden by the column. R five, three 6-sided and two 7-sided and 

 rising above the others; articular facets crescent-shaped. Anal 

 and radianal plates present. Ventral sac long and tubular, ex- 

 tending the full length of the arms. Arms long, branching and 



