198 TESTACEOUS MOLLUSCA. 
in Lam. 6. p. 552. Ovate oblong, transverse, subdepressed, pos- 
teriorly obtuse, anteriorly obscurely angulated, striated, dark olive, 
nacre rosy ; cardinal teeth very salient and compressed in one valve, 
in the other short and bifid. Senegal and the Nile. 
U. Eeypriacus. Cail. voy. a Meroe. 2. t. 61. f. 6, 7.— 
Desh. in Lam. 6. p.353. Oval-oblong, turgid, subinequilateral, 
thin, anteriorly broad and dilated; cuticle olive rayed with yellow, 
nacre pink and iridescent ; hinge almost linear, with two teeth, 
the anterior lamella very narrow and acute. Hgypt and Senegal. 
++ + + Oblong. 
U. Brevivens. Lea. in Am. Ph. Tr. 4. (1837.) p.75. t. 6. f. 
6. Oval-oblong, subtriangular, transverse, thick, inequilateral, 
umbonal slope curved; beaks slightly prominent, ligament short, 
ventral edge subincurved in the middle; cuticle yellow and wrin- 
kled, rays small slightly curved and interrupted ; nacre pearly white, 
cardinal tooth rather small, slightly elevated and rather cleft in 
one valve, simple and emerging from a pit in the other, lateral teeth 
short and thick. 14.. 1,4.—Ohio. 
U. Terratasmus. Say. Am. Con. t. 23. Transversely oblong- 
elliptic, thinnish, convex, hinge margin parallel to the ventral and 
subrectilinear ; posteriorly very short and rounded, anteriorly slop- 
ing obliquely from the hinge margin to the rounded extremity ; 
anterior slope with two impressed lines; beaks little elevated, de- 
corticated, umbonal slope not prominent : inside white, irridescent 
anteriorly and on the margin ; lateral teeth two in each valve. 33.— 
New Orleans. 
U. Campropon. Say. Am. C. t.42.—Dercuivis. Conr. (fide 
Lea.) Transversely oblong-oval, moderately thin, a little com- 
pressed, not very inequilateral, blackish or dark brownish, dorsal 
line sinuated, obtusely angulated at each extremity ; the ventral edge 
ineurved in the middle, and rounded at each extremity: anterior 
slope somewhat compressed, with two distinct compressed lines ; um- 
bonal slope not elevated above the level of the disc ; beaks with 
small undulations, little prominent ; within milk white, a single 
rather long oblique undivided primary tooth in each valve, the 
lateralteeth rather slender towards the tip, alittle arcuated. 2..33. 
—New Orleans. 
U. Osesus. Lea. on U.1. p.106.(andTr. Am. Ph. 4.) t. 13. 
f. 26. Ovate-rhomboidal, oblique, inequilateral, inflated, thickish, 
angular anteriorly, ventral edge little rounded; beaks rather pro- 
minent, ligament long and large ; cuticle fuscous and much wrinkled, 
nacre livid white; cardinal teeth elevated and crested, lateral long 
and curved. 2. .343;.— Virginia. 
U. Horrronensis. Lea. on U. 2. (Tr. Am. 6.) p. 29. t. 9. 
J. 24. Suboblong, transverse, inequilateral, compressed, biangular 
