CRUSTACEA. 181 



extremity, transverse and produced backward into a lateral carina which 

 is indistinctly preserved upon both the specimens in hand, but has evidently 

 been similar in curvature to that in the species E. sublavis and E. pusluhsa. 

 At the posterior extremity of the dorsal Tnargin and slightly distant from 

 the hinge is a longitudinally elongate node curving gently inward and 

 backward, and continued into a low ridge parallel with, and, toward its 

 extremity, merging into the postero-dorsal margin. The dorso-lateral area 

 of the carapace is broad and evenly convex, and is separated from the 

 margins by a wide sulcus. 



Surface of the carapace ornamented upon the nodes, ridges and dorso-late- 

 ral area with pustules, which appear as strong punctae upon the cast of the 

 ventral surface, as shown in one of the specimens. 



The carapace, when in an uncompressed condition, has a length of 33 

 mm., and a width of about 20 mm. for each valve. 



Distribution. In the calcareous concretions of the Erie shales on Paine's 

 Creek. LeRoy, Lake county, Ohio. 



ELYMOCARIS, Beecher. 1884. 

 Elymocaris capsella, n. sp. 



PLATE XXXI, FIU. 4. 



Cephalothorax small, siliquoid, each valve longitudinally semi-elliptical in 

 outline, with a length equal to two and one-half times the width. Hinge- 

 line straight, extending almost the entire length of the valves, and curving 

 slightly downward or outward near the extremities. Anterior extremity 

 rectangular, rounding rapidly to the broad curve of the ventral margin. Pos- 

 terior extremity truncate and slightly incurved. Margin slightly thickened. 

 Surface convex, elevated toward the dorsum, ventrally depressed. A faint 

 node, which may indicate the position of the optic spot, is visible at about 

 one-third the length of the carapace from the anterior extremity; its posi- 



