544 NORTH AMERICAN INDEX FOSSILS. 



Fig. 1872. Dizygocrinus euconus ; side and basal view. (After Worthen.) 



L. LoBOCRiNUS Wachsmuth and Springer. 



Calyx pear-shaped to wheel-shaped. Rays more or less dis- 

 tinctly lobed, and arms in groups. B 3, large, forming a cylin- 

 drical cup thickened below. R larger than both costals together. 

 Arm openings directed upward. Arms short, cylindrical, biserial. 

 Tegmen large and high. Anal tube central, stout, and very long. 



Differs from Batocrinus in the apparent absence of respiratory 

 pores (large in that genus) and in that the interbrachials are con- 

 tinuous with the interambulacral plates, not separated from them 

 as in Batocrinus by the palmars. Mississippic. 



147. L. pyriformis (Shumard). (Fig. 1873.) Mississippic. 

 Plates of dorsal cup smooth, those of tegmen convex or nodose. 



Arms four to the ray. 



Characteristic of the Upper Burlington of Missouri, Illinois and 

 Iowa. 



148. L. aequibrachiatus (McChesney). Mississippic. 

 Differs from L. pyriformis in its less elongate calyx, depressed 



tegmen, longer arms, and shorter and more slender anal tube, 

 and in being prominently lobed between the rays. 

 Upper Burlington of Illinois and Iowa. 



149. L. nashvillae (Troost). (Fig. 1874.) Mississippic. 

 Much larger than L. pyriformis. Sides of dorsal cup less con- 

 cave and plates convex. Plates of tegmen more or less highly 

 convex. Anal tube composed of large tumid plates and one and 



