532 



NORTH AMERICAN INDEX FOSSILS. 



five other spinose or nodose plates which are separated by inter- 

 radial pieces; Anus lateral and not extended in a tube. Mis- 

 sissippic. 



105. D. unicornis Owen and Shumard. (Fig. 1858.) Mississippic. 

 Calyx spheroidal. Tegmen nearly as high as dorsal cup and 



with one long central spine. 



Plates of dorsal cup very 



convex or nodose. 



Lower Burlington of 



Missouri, Iowa and New 



Mexico. 



106. D. cornigerus (Hall) 

 (Fig. 1859.) 



Mississippic. 

 Calyx wider than high. 



Fig. 1859. Dorycrmus cornijrerus. (After pj^^^g ^f ^^^.^^j ^,^p 5^^^^^.^^ 

 Hall, Iowa Survey. ) , i n • i i 



and almost flat with but 

 slightly grooved suture lines. Tegmen hemispherical, with six 

 long, slender spines. 



Burlington of Iowa and Missouri. 

 107. D, gouldi (Hall). (Fig. i860.) Mississippic. 



Height and width of calyx about equal. Plates formed into 



Fig. i860. Dorycrinus gouldi ^ X H* (After Hall, Iowa Geol., I., 2.) 



