196 NEW UNIONISE OF THE 



Shell smooth, subtriangular, compressed, a little flattened on the sides, somewhat 

 inequilateral ; valves rather thick, thicker before ; beaks rather raised and sharp at 

 the tip ; epidermis golden yellow, striate and with obsolete rays ; cardinal teeth 

 thick, erect, striate, double in both valves ; lateral teeth short and oblique ; nacre 

 white and iridescent. 



Proc. Acad. Nat. Soi., 1859, p. 112. 



Hal.— Texas, W. Newcomb, M. D. ■ 



Cabinet of Dr. Newcomb. 

 Diam. - 6, Length 11, Breadth 1 5 inch. 



Shell smooth, subtriangular, compressed, flattened a little at the sides, somewhat 

 inequilateral ; substance of the shell rather thick, thicker before ; beaks rather ele- 

 vated and acuminate at the tips ; ligament short and rather thick ; epidermis golden 

 yellow, transversely striate, with a few small, indistinct rays and rather distant marks 

 of growth ; umbonial slope slightly raised and rounded ; cardinal teeth thick, erect, 

 striate, double in both valves ; lateral teeth rather thick, short and oblique ; anterior 

 cicatrices distinct and well impressed ; posterior cicatrices large and confluent ; dorsal- 

 cicatrices placed under the plate posterior to the cardinal teeth ; cavity of the shell 

 rather shallow ; cavity of the beaks very deep and angular ; nacre white and 

 iridescent. 



Remarks. — A single specimen only of this species is before me, sent for my exami- 

 nation by Dr. Newcomb. It has an unusual golden tint in the epidermis, stronger 

 on the posterior slope. On this specimen a few small rays may be seen. The beaks 

 are too much eroded to decide as to undulations on the tips. It is closely allied to 

 rubiginosus, (nobis,) but seems to be a smaller species and more rotund. It also re- 

 sembles Schooler of temis, (nobis,) but it has no tubercles, is devoid of the broad 

 green ray Of that species and is not so high in the keel of the posterior slope. 

 There is some resemblance to jpetrinus, Gould, but it is not so round, nor so 

 ponderous, nor so much inflated, nor is the color of the epidermis of so light and 

 bright a yellow. 



Unio Chunii. PI. 27, fig. 265. 



Testa lfevi, triangularis, inflata, ad umbones subtuniida, postice obtuse angulata, antiee rotunda, sub- 

 jequilaterali ; valvulis suberassis, antiee crassioribus ; natibus subproniinentibus, subincurvis, ad 

 apices paulisper undulatis; epiderniide rufo-fusea, obsolete radiata ; dentibus cardinalibus sub- 

 grandibus, subeonipressis corrugatisque ; lateralibus suberassis, corrugatis, subcurtis subrectisque ; 

 margarita vel alba vel rosacea vel salmonia et valde iridescente. 



Shell smooth, triangular, inflated, somewhat swollen on the umbones, obtusely 

 angular behind and round before, nearly equilateral ; valves rather thick, thicker 

 before ; beaks somewhat prominent, slightly incurved and slightly undulate at the 

 tips ; epidermis reddish brown and obscurely radiate ; cardinal teeth somewhat large, 



