178 TESTACEOUS MOLLXJSCA. 



U. AsPERRiMUS. Lea. on U. 1. ]). 81. t. 5./. 3. — Tr.Am. Ph. 

 4. t. 5. — U. QuADRULUs. Say. Am. Con. t. 53. Subquadran- 

 gular, thick, inequilateral ; anteriorly biangular, with a broad 

 smooth obtuse keel from the elevated beaks to the ventral margin, the 

 slope and also the posterior edge of the keel nodulous : cuticle 

 fuscous (in the young, yellowish brown with obsolete rays) nacre 

 pearly and irridescent : cardinal teeth very large, lateral large and 

 nearly straight. 3| . . 4|. — Ohio. 



U. ^RAGOSUS. Conr. Mon. U. p. 12. t. 6. f. 2. Suborbicular 

 inclining to subquadrate,subeqviilateral, ventricose ; anterior margin 

 direct and obtusely forming an angle with the oblique and nearly 

 straight ligamental edge ; with an indistinct narrow furrow (form- 

 ing a deep sinus at its termination) and two approximate series of 

 very prominent irregular tubercles, anterior slope slightly concave, 

 with a few narrow rib-like tubercles more prominent near the 

 margin ; umbo narrow, prominent ; beaks much incurved, pointed, 

 tuberculated : cuticle brown, usually with two or three broad, 

 widely interrupted green rays. 2 . , 2^. — Ohio. 



U. Philipsii. Conr. Mon. t. b. f. 1. j). 9. Subovate, pos- 

 teriorly rounded ; anterior side narrowed angulated above and 

 below with a wide furrow and a few small tubercles, extremity 

 Bubincurved : umbonal slope straight, subcarinated and tubercu- 

 lated ; anterior slope concave, indistinctly tuberculated ; ligamental 

 edge oblique, rectilinear : ventral edge swelling centrally incurved 

 in front ; cuticle yellowish brown, with indistinct filiform rays over 

 the rather prominent umbo, disc with a single row of irregular 

 tubercles in the centre, some of which are elongated and grooved : 

 inside white, cardinal teeth rather small, direct, double in each 

 valve. If . . 2. — JR. Wabash, N. America. 



U. PusTULATUs. Lea. 071 U. 1. p. 89. t. 7. f. 9. Rounded- 

 obovate, transverse, equilateral, inflated, thick, simply rounded 

 posteriorly, the granulated anterior and the anterior ventral edge 

 incurved : with two vei'tical rows of tubercles, one nearly central, 

 the other along the umbonal slope ; beaks elevated, ligament short 

 and thick ; cuticle yellowish brown, nacre white and irridescent : 

 cardinal teeth large, lateral short and straightish. l-j^^. . 2^^. — Ohio. 



U. ScHOOLCRAFTENSis, Lea. Tr. Ph. Am. t. 3. f. 9. — U. 

 Prasinus. Conr. Transversely obovate, compressed, thickish, 

 slightly tuberculated behind the umbonal slope, anteriorly longer 

 and angulated above and below ; beaks elevated, ligament short : 

 cuticle yellow with the rays green and broad (particularly the 

 central one) ; nacre pearly white and irridescent ; cardinal teeth 

 elevated, the lateral straight and lamellar. 1to'"W%- — -^• 

 America. 



U. Apiculatus. Say. Am. C. t. 52. Subquadrate, the dia- 

 meters subequal, obtusely subangulated, compressed and rather 



