ECHINODERMATA—CRINOIDEA. 545 



one half inches from its base surrounded by a ring of five plates 

 bearing long (one inch or less), horizontal spines. (Type of 

 genus.) 



Keokuk of Kentucky, Tennessee, Illinois, Missouri and Iowa. 



Fig. 1873. Lobocrinus pyriformis, X FiG. 1874. Lobocrinus nashvillce, X 

 %. (After Meek and Worthen, 111. %. (After Worthen.) 

 Geol., V.) 



LI. Macrocrinus Wachsmuth and Springer. 



Calyx biturbinate or subovoid. B large, forming a cylindrical 

 cup. R frequently larger than both costals together. Arm bases 

 in contact laterally, except posteriorly where they are separated 

 by a small interbrachial plate. Arm openings directed outward. 

 Arms 12 to 16, long, with incurving tips. Tegmen shorter than 

 dorsal cup. Anal tube exceedingly long, almost central. 



Differs from Batocrinus in the more elongate calyx, fewer and 

 longer arms, and in having but five pairs of respiratory pores; 

 from Eretmocrinus in its straight and nearly certral anal tube and 

 m arm structure. Mississippic. 

 35 



