CHIEFLY OF THE UNITED STATES. 277 



obscurely rayed and with distant marks of growth ; umbonial slope flattened ; 

 posterior slope carinate, with two impressed lines in each valve; cardinal teeth 

 small, oblique and compressed, single in the right and double in the left valve; 

 lateral teeth very long, lamellar and slightly curved; anterior cicatrices confluent, 

 large and slightly impressed; posterior cicatrices confluent, very large and very 

 slightly impressed ; dorsal cicatrices placed in the centre of the cavity of the beaks ; 

 cavity of the shell wide and shallow; cavity of the beaks shallow and wide; nacre 

 white and iridescent. 



Remarks.— Two rather young specimens of this species were sent to me by Dr. 

 Lewis, of Mohawk, N. Y., to whom they were given by Col. Jewett, of Utica, N. Y., 

 who collected them in Florida. The species is nearly allied to obesu^ (nobis) .vJt 

 seems to be distinct, from the fact of its being wider in proportion and in being^more 

 compressed. The beaks of these specimens are eroded, but there is enough^of the 

 undulations visible to assure us of the group to which the species belongs. 



Unio Bisselianus. pi. 37, fig. 90. 



Testa lasvi, oblonga, sublenticulari, iuEequilaterali, postice obtuso-angulata, antice rotunda ; valvulis sub- 

 crassis, antice aliquanto crassioribus ; natlbus prominulis, ad apices concentrico-undulatis ; epider- 

 mide tenebroso-oliva, obsolete radiata; dentibus cardinalibus crassiusculis, compressis, subelevatis 

 creoulatisque; lateralibus sublongis, lamellatis subcurvisque; margarita earnea et valde' iridescente. 

 Shell smooth, oblong, sublenticular, inequivalve, obtusely angular behind, round 

 before; valves rather thick, somewhat thicker before; beaks a little prominent, con- 

 centrically undulate at the tips; epidermis dark olive, obscurely radiate ; cardinal 

 teeth oblique, compressed, somewhat raised ; lateral teeth rather long, lamellar and 

 somewhat curved ; nacre flesh color and very iridescent. 

 Proe. Acad. Nat. Sci. 1867, p. 81. 

 Sab.— BisseVs Pond, Charlotte, N. C, C. M. Wheatley. 

 My cabinet and cabinet of Mr. Wheatley. 



^^'''™- ■^' Length 1-6, Breadth 2-7 inches. 



Shell smooth, oblong, sublenticular, inequivalve, obtusely angular behind, round 

 before; substance of the shell thick, somewhat thicker before; beaks a little promi- 

 nent, concentrically undulate at the tips; ligament rather long and thin; epidermis 

 dark olive, obscurely radiate, with rather close marks of growth ; umbonial slope 

 flattish and somewhat darkened ; posterior slope carinate and furnished with two im- 

 pressed lines in each valve; cardinal teeth oblique, compressed, somewhat raised, 

 single in the right and double in the left valve; lateral teeth rather long, lamellar 

 and somewhat curved ; anterior cicatrices distinct, rather large and well impressed- 

 posterior cicatrices confluent, large and slightly impressed; dorsal cicatrices placed 

 across the cavity of the beaks ; cavity of the shell wide and somewhat deep ; nacre 

 flesh color and very iridescent. 



