36 DESCRIPTION OF FIFTY-TWO SPECIES OF UNIONID^. 



thick and dark brown ; epidermis yellowish, without rays, with somewhat distant 

 marks of growth; umbonial slope very obtusely biangular; posterior slope carinate, 

 narrow elliptical, with an obscurely impressed line from the beaks to the posterior 

 margin ; cardinal teeth rather small, subcompressed and double in both valves ; 

 lateral teeth rather small and oblique; anterior cicatrices distinct, rather large and 

 well impressed; posterior cicatrices distinct, rather large and well impressed; dor- 

 sal cicatrices placed above the centre ; cavity of the shell shallow ; cavity of the 

 beaks obtusely angular and somewhat deep; nacre white or tinted with salmon 

 color and very iridescent. 



Remarks. — Two specimens were received by me from Dr. Lewis and Mr. Wheat- 

 ley. Neither of the shells was perfect at the beaks. The character of the undu- 

 lations of the tips is therefore unknown. In outline it is between gihler (nobis) 

 and ruUginosus (nobis). Along the inferior margin the epidermis is somewhat 

 rough and imbricate. One of the specimens before me has a few obsolete rays. 



Unio Andersonensis. pi. 12, fig. 33, 



Testa ]83vi, triangulari, inflata, ad latere planulata, emarginata, valde insequilaterali, postice obtuse 

 angulata, antice oblique rotundata; valvulis percrassis, antice crassioribus ; natibus valde elevatis, 

 tumidis recurvatisque ; epidermide vel luteola vel fusca, obsolete radiata ; dentibus cardinalibus 

 crassis, crenulatis, conicis ; lateralibus erassis, curtis subcurvisque ; margarita argentea et irides- 

 cente. 



Shell smooth, triangular, inflated, flattened at the sides, emarginate, very ine- 

 quilateral, obtusely angular behind, obliquely rounded before; valves very thick, 

 thicker before; beaks very much raised, swollen and recurved; epidermis yellowish 

 or brownish, obscurely rayed ; cardinal teeth thick, crenulate, conical ; lateral teeth 

 thick, short and somewhat curved ; nacre silver white and iridescent. 

 Proc. Acad. Nat. Sci., 1872, p. 155. 



Hah. — Holston River; and Clinch River, Anderson Co., East Tennessee, Miss 

 A. E. Law. 



My cabinet, and cabinet of Dr. Lewis, 

 Diam, 1-4, Length 1-7, Breadth 1-6 inch. 



Shell smooth, triangular, inflated, flattened at sides, emarginate, very inequi- 

 lateral, obtusely angular behind, obliquely rounded before ; substance of the shell 

 very thick, thicker before; beaks very much raised, swollen and recurved ; ligament 

 short, thick and chestnut brown; epidermis yellowish or brownish, obscurely rayed, 

 with rather close marks of growth ; umbonial slope obtusely angular ; posterior 

 slope cordate; cardinal teeth thick, crenulate, conical; lateral teeth very thick, 

 short, somewhat curved and corrugate; anterior cicatrices distinct, rather small 



