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 abovethe dorsal line : cuticle brown ; inside 
purplish ; teeth thick, the cardinal direct. 1.. 21.—fh. Savannah, 
N. America. 
U. Nasurus. Say. En. Am. Nic.—Barnes.—Swain. Zool. Il. 
lst Ser.—Lis.t. 151. f. 6.—Mya Nasuta. Wood. S.t. 1. fi 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. 21 ..23.—Delanare. 
U. Fisnerianus. 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. 1,1,.. 271,.—R. Chester, North America. 
U. Javensis. 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. 14..23.—Florida. 
U. Lucusris. Lea. (Tr. Am. Ph. 6.) t. 9. f. 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. 1.3, .. 24.—Near Darien. 
U. Marerinauis. Lam. 41.— EH. t. 247. f.1. Ovate-oblong, 
transverse, subrhombiec, thin, brown with concentric yellow or tawny 
bands towards the margin; inside bluish, cardinal tooth small and 
compressed. 3:—Bengal.! 
U. Ints. Lea. Tr. Am. Ph. 3. t. 11. ff 18.—U. Nesutosuvs. 
Conr. Narrow elliptical, inequilateral, subyentricose, 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. +.. 13.— Ohio. 
U. Tenvissimus. Lea.--Sympnonorta T. Lea. Tr. Am. Ph. 3. 
tf. ll. f. 21.—Purpurascens. Sivain.—U. VeLtum. Say. 
Narrow-elliptical, inequilateral, transversely wrinkled, compressed, 

' U. ANopontina. Lam. 47. is the same species, fide Lea. 
