208 TESTACEOUS MOLLUSCA. 
U. Nasuta. Lam.—U. Ditatatus. Conr. Transversely elongated, 
heavy, gibbous, anteriorly rapidly attenuated and produced, pos- 
teriorly narrow, rounded, ventral edge little rounded ; beaks flat ; 
cuticle blackish brown finely striated and deeply wrinkled trans- 
versely, nacre purplish, teeth crenate, the lateral rough, very thick, 
incurved. 1-2,.. 4.—N. America. 
U. Arcrior. Lea. on U.2. (and Tr. Am.6.) p. 10. t. 4. f. 
10. Narrow elliptical, transverse, obliquely rounded posteriorly, 
attenuated and subangular anteriorly, flattened on the sides, thin- 
nish, the beaks compressed and undulated, ligament rather long 
and slender; cuticle dark brown and wrinkled, nacre white or 
salmon colour ; cardinal teeth small, the laterallong. Ohio. 
U. Paraconicus. D’ Orb. S. Am. t.70. f. 1. to 4. Oblong, 
compressed, thickish, smooth or strigillated, blackish or yellowish 
brown ; posteriorly very short and rounded, anteriorly produced and 
attenuated at the rounded extremity, ligamental edge nearly straight 
and long, cardinal tooth thick and crenulated, the lateral very elon- 
gated, inside bluish white or pink. 13. .32%—Patagonia. 
U. Vauenanianus. Lea. on U. 2. (and Tr. Am. 6.) p. 5. 
t.3. f. 5.—Carournensis. Rav. Transversely ovate, somewhat 
inflated, rather thin, enlarged towards the anterior ventral margin, 
before which it is subincurved, anterior side obtusely aciminated, 
its dorsal edge nearly straight; beaks scarcely prominent, cuticle 
blackish, obscurely rayed anteriorly, nacre salmon coloured : cardinal 
teeth small and erect, the lateral straight. 11..2.—8. Carolina. 
tttttttt Obovate. 
U. Purpuratus. Lam. 6.—Ater. Lea. on U. (Tr. Am. 3.) 
t. 7. f.9.—U. Lucusris. Say. Am. C. t. 43.—U. Poutsonr. 
Conr. 'Transversely ovate, inequilateral, much inflated, much 
broader and obtusely truncated anteriorly, the ventral edge little 
rounded, anterior dorsal edge rather elevated ; thick, the beaks 
slightly projecting and decorticated ; cuticle black, wrinkled trans- 
versely, nacre rose colour; cardinal teeth erect and crestlike, the 
lateral granulated and straight. 3..43.—Missisippi. 
U. RuomsBeus. Wagn. Test. Braz. t. 28. f. 1,2. Rounded- 
ovate, oblique, anteriorly dilated, and narrowed posteriorly, thick, 
transversely striated or grooved, rounded at both ends, dorsal edge 
more arcuated than the ventral; beaks depressed and decorticated, 
cuticle brown, nacre bluish white : cardinal tooth thick, compressed, 
substriate, bifid. 2,1,..3.—Brazil. 
U. Cuprinus. Lea. on U.1. (Tr. Am.4.) t. 12. f. 24.—Mer- 
TALLICUS.—Say. Ovate, transverse, inequilateral, inflated, thin, 
rounded at both ends, broader anteriorly, the ventral margin little 
rounded and much incurved in the middle; the beaks small, pointed, 
with concentric undulations, ligament long and lanceolate: cuticle 
