206 TESTACEOUS MOLLUSCA. 



ligamental edge parallel to the line of the ventral which is scarcely 

 arcuated and subincurved in the middle ; ridges of the umbonal slope 

 obtuse, beaks not raised above the dorsal line : cuticle brown ; inside 

 purplish ; teeth thick, the cardinal direct. 1 . . 2-J. — R. Savannah, 

 N. America. 



U. Nasutus. Say. En. Am. Nic. — Barnes. — Swain. Zool. II. 

 1st Ser.—Lis. t. 151. /. 6.— Mya Nasuta. Wood. S. t. 1. /. 4. 

 Elongated- oblong, transverse, posteriorly short and rounded, an- 

 teriorly very produced and obtusely acuminated ; ligamental edge 

 straight : thin, compressed, horn-coloured brown or olive (some- 

 times obscurely rayed with green) nacre bluish white : teeth 

 crenated. 2\ . . 2%. — Delaware. 



U. Fisherianus. Lea. Tr. Am. 6. t. 4. f. 8. Transversely 

 elongated, acutely angular anteriorly, very short and rounded pos- 

 teriorly, ventral edge not incurved, compressed and thin ; beaks and 

 umbones flattened, ligament thin and short : cuticle dark brown and 

 smooth : nacre purple ; cardinal teeth lamellar, the lateral long and 

 somewhat curved. 1 ^ . . 2^. — R. Chester, North America. 



U. Jayensis. Lea. on U. 2. (and Tr. Am. 6.) p. 28. t. 9. 

 f. 23. Narrow- elliptical, transverse, very inequilateral, anteriorly 

 subangular, thin, subcarinate, ventral edge little rounded, beaks 

 somewhat prominent, ligament rather long ; cuticle brown and 

 (apparently) rayless, nacre purple ; cardinal teeth compressed, the 

 lateral long and straight, l^ . . 2\. — Florida. 



U. Lugubris. Lea. {Tr. Am. Ph. 6.) t. 9. ,/. 25. Elliptical, 

 transverse, somewhat inflated, inequilateral, anteriorly biangular, 

 posteriorly rounded, thickish, ventral edge little rounded, the beaks 

 rather prominent, ligament thin and shortish : cuticle nearly black, 

 (apparently rayless) ; nacre purple ; cardinal teeth compressed, 

 lateral longish and somewhat curved. 1-^ . . 2\. — Near Darien. 



U. Marginalis. Lam. 41. — E. t. 247. f. 1. Ovate-oblong, 

 transverse, subrhombic, thin, brown with concentric yellow or tawny 

 bands towards the margin ; inside bluish, cardinal tooth small and 

 compressed. 3; — Bengal. 1 



U. Iris. Lea. Tr. Am. Ph. 3. £.11. /. 18.— U. Nebulosus. 

 Conr. Narrow elliptical, inequilateral, subventricose, thin, rounded 

 at both ends, beaks slightly prominent : ligament rather long and 

 thin ; cuticle yellowish green with numerous narrow rays, nacre 

 bluish white : cardinal teeth double in the left valve, subbifid in the 

 right, small and erect, the lateral long and thin. 4 . . 1^. — Ohio. 



U. Tenuissimus. Lea. — Symphonota T. Lea. Tr.Am. Ph. 3. 

 t. 11. f. 21. — Purpurascens. S?vain. — U. Velum. Say. 

 Narrow-elliptical, inequilateral, transversely wrinkled, compressed, 



1 U. Anodontina. Lam. 47. is the same species, fide Lea. 



