88 NEW UNIONID.?!: OF THE UNITED STATES. 



Shell smooth, oblique, swollen, very inequilateral, rounded behind and round be- 

 fore ; valves thick, thicker before ; beaks raised, somewhat incurved ; epidermis pale 

 yellow, spotted, striate below ; cardinal teeth small, pyramidal and striate ; lateral 

 teeth short, thick and somewhat oblique ; nacre silver white and iridescent. 

 Proc. Acad. Nat. Sci. 1861, p. 60. 



Hah. — Cahawba Eiver, Alabama; E. R. Showalter, M. D. 



My cabinet and cabinet of Dr. Showalter. 

 Diam. -7, Length 1, Breadth 14 inch. 



Shell smooth, oblique, swollen, very inequilateral, rounded behind and round be- 

 fore ; substance of the shell thick, thicker before ; beaks raised, somewhat incurved ; 

 ligament small and very light brown ; epidermis pale yellow, nearly honey yellow, with 

 two or three small, isolated spots on the umbonial slope at the upper lines of growth, 

 which are rather distant, striate at the basal margin, and smooth and bright at the 

 beaks; umbonial slope somewhat raised and rounded ; posterior slope slightly carinate, 

 elliptical, with two obscure lines on each valve from the beaks to the margin ; cardinal 

 teeth small, pyramidal and striate ; lateral teeth rather short, thick and somewhat 

 oblique; anterior cicatrices distinct, small and deeply impressed ; posterior cicatrices 

 distinct, rather small and well impressed ; dorsal cicatrices, placed above the centre 

 of the cavity of the beaks ; cavity of the shell rather shallow ; cavity of the beaks 

 shallow and rounded ; nacre silver white and iridescent. 



jBemarfo.-T-Several specimens are before me ; none were received in alcohol, and 

 therefore the soft parts are not observed. In outline it is nearly allied to interventus, 

 herein described ; but it is more oblique and has different markings, that species having 

 obscure rays, while this has simple, dark green spots before the umbonial slope at the 

 intersection of the lines of growth. There is a group of species which have this 

 peculiar character of well defined spots in a row before the umbonial slope. In out- 

 line it is also very near to Hanleyianus (nobis), and is about the same size, but it 

 differs in having a much lighter epidermis, more distant lines of growth, and in having 

 the above mentioned spots. The lines of growth, without being dark, are well de- 

 fined. 



Unio interventus. pi. 11, fig. 233. 



Testa hevi, subobliqua, subcompressa, insequilaterali, postice rotundata, antice rotunda ; valvulis crassiusculis, 

 antice crassioribus ; natibus elevatis; epidermide luteo-cornea, superne radiata, inferix? striata, ad 

 umbones micanti ; dentibus cardinalibus parvis, pyramidatis striatisque ; lateratibus subcurtis, crassis, 

 subobliquis subcurvisque ; margarita argentea et valde iridescente. 



Shell smooth, somewhat oblique, rather compressed, inequilateral ; rounded behind 

 and round before ; valves rather thick, thicker before; beaks raised ; epidermis yellowish 

 horn color, rayed above, striate below, shining on the umbones ; cardinal teeth small, 



