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. If . . 5. — Georgia, 

 N. America, 



U. Folliculatus. Lea, on U. 2. p. 38. (and Tr. Am. 6.) t. 

 ll.y. 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. | . . 2|. — R. Savannah. 



U. Rectus. Lam. — Pr^elongus. Barnes in Sil. J, 6. — 

 Hild. — Mya Pilelonga. Wood. S. 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 t 7 q. . . 6§. — N. Ame- 

 rica. 



U. Dehiscens. Say. Am. Con. t. 24. — Oriens. Lea. on 

 U.l.p. 83. (and Tr. Am. Ph. 4.) t. 6. /. 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. 1-^..2J. — Ohio. 



U. Angustatus. 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. 1-jL . . 2-|. — S. Carolina. 



U. Lanceolatus. Lea. Tr, Am. Ph. 3. t. 3. /. 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- T 7 ff . . l T 7 y. — Tarborough. 



U. Anodontoides. Lea. on U. 1. p. 91. (and Tr. Am. Ph. 4.) 

 /, S.f. 11. — U. Teres. Conr. Narrow elliptical, transverse, inequi- 

 lateral, inflated, thickish, posteriorly rounded, anteriorly subat- 



