122 PALEONTOLOGY OF ILLINOIS. 



Position and locality: From the upper part of the Keokuk 

 limestone, Warsaw, 111. 

 Collector, A. H. Worthen. 

 No. 2502 of the Illinois State Museum. 



EDMONDIA ILLINOIENSIS. Worthen. 



PL XVIII. Figs. 7-7a. 



Edmondia UUnoiensis, Worthen, March, 1884. Bulletin No. 2 of the Illinois Slate Mus- 

 eum of Natural History, page IN. 



Shell of medium size, transversely sub-oval, convex, broadly 

 rounded at the extremities; dorsal margin straight behind the 

 beak for a.bout two-thirds its length, and thence rounding into 

 the posterior border; basal margin slightly sub-ovate; beak de- 

 pressed and located about one-third the entire length of the 

 shell from the anterior extremity. Surface of the cast marked 

 by distinct parallel lines of growth. 



Length 1% inches; height lVi inches; convexity of the valves 



about 5 /i6 mcn - 



This is a smaller and more convex shell than the preceding 

 species, and shows none of the fine concentric stria? that appear 

 on the E. vaiKoviennix. 



Position and locality: Same as the preceding species. 



Collector, A. H. Worthen. 



No. 2503 of the Illinois State Museum. 



CLINOPISTHA KADIATA. Hall, sp. 



PI. XIX, Fig. 3, and PI. XXI, Fig. 2. 



Shell elongate oval, height rather less than two-thirds the en 

 tire length; valves moderately convex; posterior extremity 

 truncated, anterior rounded; hinge line straight and equaling 

 about one-half the entire length of the shell. 



Beaks depressed and incurved posteriorly. Ventral margin 

 slightly sinuate near the posterior extremity, and sub-parallel 

 with the dorsal. 



Surface ornamented with obscure lines of growth and numer- 

 ous radiating stria? that cross the shell diagonally from the 

 beaks to the anterior and ventral margins. 



Length l/] 6 inches; height Ir> /, (! inch; thickness n /i( 5 inch. 



Position and locality: Coal measures, Mercer county, 111. 



Collector, Tyler McWhorter, I0s<|. 



No. 2586 of the Illinois State Museum. 



