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. subl( 2 vis and E. pustulosa. 
At the posterior extremity of the dorsal margin 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, Beechek. 1884. 
Elymocaris capsella, n. sp. 
PLATE XXXI, FIO. 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- 
