208 TESTACEOUS MOLLtJSCA. 



U. Nasuta. Lam. — U. Dilatatus. Cow. Transversely elongated, 

 heavy, gibbous, anteriorly rapidly attenuated and produced, pos- 

 teriorly naiTow, 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, ly^ • • ^' — ^' ■^'f^^^rica. 



U. Arctior. Lea. on U. 2. (an^ Tr. Am. 6.) p. 10. t. A. 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 lateral long. Ohio. 



U. Patagonicus. 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. 1| . . 3f . — Patagonia. 



U. Vaughanianus. Lea. on U. 2. (and Tr. Am. 6.) j). 5, 

 t. 3. f. 5. — Carolinensis. Rav. Transversely ovate, somewhat 

 inflated, rather thin, enlarged towards the anterior ventral margin, 

 before which it is subincurved, anterior side obtusely acuminated, 

 its dorsal edge nearly straight ; beaks scarcely prominent, cuticle 

 blackish, obscurely rayed anteriorly, nacre salmon coloured : cardinal 

 teeth small and erect, the lateral straight. \^ , . 2. — *S'. Carolina. 



tttttttt Obovate. 



U. Purpuratus. Lam. G.—Ater. Lea. on U. {Tr. Am. 3.) 

 t.7.f.9. — U. LuGXJBRis. Say. Am. C if. 43.— U. Poulsoni, 

 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 

 shghtly projecting and decorticated ; cuticle black, wrinkled trans- 

 versely, nacre rose colour ; cardinal teeth erect and crestlike, the 

 lateral granulated and straight. 3 . . 4i. — Missisippi. 



U. Rhombeus. Wagti. Test. Braz. t. 28. /. 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. 2yV . . 3. — Brazil. 



U. CupRiNXjs. Lea. on U. 1. {Tr.Am.A.) t. 12. /. 24.— Me- 

 tallicus. — Soy. 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 



