188 TESTACEOUS MOLLUSCA. 
cuticle yellowish, covered with green rays, nacre white; cardinal 
teeth small, the lateral long and straight. 14..14.— Ohio. 
U. Suxcatus. Lea. on U. 1. p. 44. (f Tr. Am. Ph.3.) t. 8. 
f.12.—at.—Say. Am. Con. t. 5.—Rupisunvus (female). Say. 
Am. C. t.5.—Hat. Subelliptic, short very thick, inequilateral, 
ventricose, ventral edge incurved anteriorly by an oblique hollow 
running from the beaks, which are nearly terminal obtuse eroded 
and prominent; cuticle olive brown, wrinkled, with numerous fine 
radiating hair-like lines, (except posteriorly), nacre purple : the 
teeth large and double in both valves. 1,55 . . 233;.— Ohio. 
U. Haystanus. Lea. Trans. Am. Ph. 5. t. 3. f. 7. Sub- 
rotund, transverse, subventricose, scarcely thick, subequilateral, but 
rather longer anteriorly, dentated at the anterior ventral edge, de- 
pressed before the umbonal slope; beaks thick and elevated: cuticle 
yellowish brown, very smooth and shining, the rays obsolete, nacre 
chocolate : cardinal teeth lobed, the lateral smooth and straight. 
4..1—N. America. 
U. Exuiesis. Lea. on U.1. p. 10. (§ Tr. Am. 3.) t. 4. f. 4. 
—Eat.—Breviatis? Sow. Elliptical, ventricose, very thick, 
rounded at both ends ; beaks all but terminal, decorticated ; surface 
somewhat wrinkled, the cuticle smooth and reddish brown, the 
nacre pearly white and silvery, teeth large and well defined, the 
cardinal crenulated. 15%, . . 2-35.— Ohio. 
U. Castangus. Lea. on U.1.p.101. (§ Tr. Am. 4.) t. 11. 
f- 21. Obovate, transverse, thick, oblique, inequilateral, inflated, 
rounded at both ends, ventral margin very convex, beaks prominent, 
ligament short ; cuticle dark brown, becoming yellowish, with a few 
rays anteriorly, nacre very pearly and irridescent: cardinal teeth 
large, lateral short and straightish. ¢...1.—. Alabama. 
teutedy [Ovel. 
U. Tamricoensis. Lea. on U. 2. p. 24. (§ Tr. Am. Ph.) 
t.7. f. 18. Ovate, transverse, inflated, subcarinated, imequilateral, 
thick, beaks somewhat prominent, ligament large and long: cuticle 
blackish and (apparently) rayless, nacre white and irridescent 
(rarely rose colour): cardinal teeth large, lateral long straightish 
and large. 24...4,3,.—Meaico. 
U. Lecontianus. Lea. on U. 2. p. 40.t. 12. f. 35.  Ellip- 
tical, transverse, inequilateral, somewhat inflated, thick, ventral 
and dorsal edges straightish and subparallel, anterior side subbi- 
angular; beaks slightly elevated ; cuticle yellowish brown and 
obscurely rayed, nacre pale salmon coloured, cardinal teeth small, 
the lateral long and separate. 1%,..24.—Greorgia in America. 
U. Perpix. Lea. Trans. Am. Ph.5.t. 11. f. 31. Trans- 
verse, elliptical, inflated, thickish, anteriorly subangulated and 
rather longer, ligamental edge straight, ventral edge entire ; beaks 
