526 



NORTH AMERICAN INDEX FOSSILS. 



87. C. limabrachiatus (Hall). Mississippic. 



Size and shape much as in C. proboscidialis but arm bases 

 slightly projecting. Arms six to a ray, flattened, their plates cor- 

 rugated and marked on the upper margin by file-like ridges. 



Lower Burlington of Iowa. 



Fig. 1851. Cactoci'inus proboscidialis : ^, calyx with broken vault, X ^ ^^ > ^^^> 

 ambulacral canals; r, digestive sac ; 0^ ^ arm openings; j, "convoluted organ"; b^ 

 ambulacra! canal, magnified. (After Meek and Worthen, 111. GeoL, V. ) 



88. C. proboscidialis (Hall). (Fig. 1851.) Mississippic. 

 Arms crowded, long and heavy, tapering above to a fine point. 



Anal tube extends beyond the arms. 



Characteristic of the Lower Burlington of Missouri, Iowa and 

 New Mexico. 



89. C. reticulatus (Hall). Mississippic. 

 In size and outline resembling C. proboscidialis but somewhat 



more slender. Ornamentation of dorsal cup as in that species. 



Fig. 1852. Cactocrinus cotlatus. (After Fig. 1853. Amphoracrinus divergens, 

 Hall, Iowa Gaol., I., 2.) X %- (After Meek and Worthen.) 



