204 TESTACEOUS MOLLUSCA. 
riorly, produced and subcuneiform anteriorly, ligamental edge 
straightish, ventral strongly incurved, sides and umbones flattened; 
umbonal slope elevated, beaks small, ligament thin and long ; cuti- 
cle blackish brown, (sometimes with obsolete rays), nacre purple 
and irridescent : cardinal teeth oblique, single in one valve, double 
in the other, the lateral very long and straight. 12..5.— Georgia, 
N. America. 
U. Fotuicunatus. Lea. on U. 2. p. 38. (and Tr. Am. 6.) t. 
11.f. 33. Transversely elongated, very narrow, rather thin, very 
inequilateral, rather compressed, flattened at the sides, rounded 
posteriorly, subbiangular anteriorly, ventral edge slightly incurved 
in the middle; beaks scarcely prominent ; cuticle very dark brown, 
nacre purple and irridescent: cardinal teeth small, the lateral long 
and somewhat curved. +4..22.—J?. Savannah. 
U. Recrus. Zam.—Pratonevus. Barnes in Sil. J. 6.— 
Hild—Mya Pratonea. Wood. 8S. f. 11. Much elongated 
transversely, narrow, thick, tumid, the beaks flat, rounded at both 
ends, but anteriorly attenuated and produced, posteriorly short, 
ventral edge little rounded (incurved in the old): cuticle blackish 
brown with fine interrupted wrinkles in longitudinal rows, (in the 
young smooth glabrous and rayed with yellowish olive) : nacre 
purplish, the lateral tooth long and thin. 2,%5...62.—N. Ame- 
rica. 
U. Deniscens. Say. Am. Con. t. 24.—Ortens. Lea. on 
U. 1. p. 83. (and Tr. Am. Ph. 4.) t. 6. f. 5. Elongated oblong, 
transverse inequilateral, compressed, very thin, anteriorly attenuated, 
ventrally not incurved, little rounded; beaks scarcely prominent 
and retuse, ligament linear: cuticle yellowish with oblique inter- 
rupted green rays, nacre bluish white and irridescent, purple under 
the beaks : cardinal teeth small and imperfect, lateral undivided 
and imperfect. 151,..24.—Ohio. 
U. Aneustatus. Lea. on U. 1. p. 124. (and Tr. Am. Ph.4.) 
t.17. f. 43. Transversely elongated oblong, angulated anteriorly 
and its dorsal edge straightish, the ventral incurved in the middle ; 
thin rather compressed, the beaks slightly elevated and undulated at 
the tips; cuticle reddish brown with the rays obsolete, nacre dull 
purple: cardinal teeth elevated and compressed, lateral long and 
nearly straight. 11, ..24.—S. Carolina. 
U. Lanceoxatus. Lea. Tr. Am. Ph. 3.t. 3. f. 2.  Trans- 
versely elongated, compressed, attenuated and subangular anteriorly, 
thin, ventral edge not incurved, beaks scarcely prominent; cuticle 
lemon or olive yellow and glabrous, nacre salmon colour and irrides- 
cent : cardinal tooth sharp and oblique. =%,..145.-—Tarborough. 
U. Anopontoipes. Lea.on U. 1. p. 91. (and Tr. Am. Ph.4.) 
t. 8. f. 11.—U. Terres. Conr. Narrow elliptical, transverse, inequi- 
lateral, inflated, thickish, posteriorly rounded, anteriorly subat- 
