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. 

 11. y. 33. Transversely elongated, very narrow, rather thin, very 

 inequilateral, rather compi-essed, 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^longus. Barnes in Sil. J. 6. — ■ 

 Hild. — Mya Pr^longa. Wood. S. f. II. 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. 2Jq. . . 6|. — N. Ame- 

 rica. 



U. Dehiscens, Sai/. Arn. Con. t. 24. — Oriens. Lea. on 

 U.l.'p.m. (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. lJo..2|. — 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, -/q . . \-^q. — Tarboro7igh. 



U. Anodontoides. Lea. on U. l.j). 91. (and Tr. Am. Ph. 4.) 

 t. 8.f. 11. — U. Teres. Conr. Narrow elliptical, transverse, inequi- 

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



