00 NEW UNIONID/E OF THE UNITED STATES. 



/foZ/.— Alabama? -T. R. Ingalls. M. D. 



My cabinet. 

 Diam. -5, Length -9, Breadth 1-1 inch. 



Shell smooth, subrotund, compressed, inequilateral, nearly round behind, round 

 before ; substance of the shell rather thick, thicker before ; beaks rather prominent, 

 with a few rough undulations at the tips; ligament short, thin and yellowish brown; 

 epidermis honey yellow, ornate, with well marked green spots below the marks of 

 growth, which are rather distant, bright and shining above and striate below along 

 the margin ; umbonial slope slightly raised and rounded ; posterior slope narrow, very 

 slightly raised with an impressed line on each valve from the beaks to the posterior 

 margin ; cardinal teeth rather small and sulcate ; lateral teeth short, oblique and 

 straight; anterior cicatrices distinct, small and well impressed ; lateral cicatrices distinct, 

 small and moderately impressed ; dorsal cicatrices placed under the plate and along 

 the base of the cardinal tooth ; cavity of the shell shallow and wide ; cavity of the 

 beaks shallow and subangular ; nacre silver white and very iridescent. 



Bemarlcs. — The description is made from a single specimen which has been in my 

 possession several years. It was sent to me by Dr. Ingalls to describe, if new, with 

 the privilege of keeping it in my cabinet. Being in frequent receipt of specimens 

 from Alabama, Georgia and Tennessee of species belonging to this group and 

 nearly allied to this species, I delayed in hopes of getting other specimens, but I have 

 been disappointed, and I regret to describe it without others, both older and younger. 

 I doubt if this specimen be full grown, while I suspect it to be nearly so. In outline 

 it is close to coccineus, Hild., but in color and spots it is nearly allied to Bighyensis 

 (nobis) and oviformis, Con. It differs form the former in being rounder and having 

 less maculation or rays, from the latter in not being oblique and having less macula- 

 tion or rays. The maculations are formed by bundles of short, green, capillary lines 

 immediately below the marks of growth, and are strikingly in contrast with the clear 

 yellow of the surrounding epidermis. In this specimen the two valves differ in re- 

 gard to these maculations; they are fewer and larger in the right valve, and more 

 numerous and thinner in the left. 



Unio trinaceus. pi. 12, fig. 235. 



Testa laevi, triangulari, ad umbones tumida, insequilaterali, postice angulata, antic^ oblique rotundata ; 

 valvulis crassis, anticc et postice crassioribus ; natibus prominentibns, tumidis; epidermidc fusco- 

 virente, obsolete radiata, striata ; dentibus cardinalibus parviusculis, depressis striatisque ; lateralibus 

 subcurtis, pererassis, obliquis, corrugatis reetisque; margarita argentea et iridescente. 



Shell smooth, triangular, swollen at the umbones, inequilateral, angular behind, ob- 

 liquely rounded before ; valves thick, thicker behind and before ; beaks prominent and 

 swollen ; epidermis brownish green, obscurely rayed, striate ; cardinal teeth somewhat 



