UNITED STATES AND NOKTIIEKN MEXICO. 25 



large or distinct. The cardinal teeth arc very much alike, but the lateral teeth of 

 scifiilios are longer. It has also a close resemblance on the other side to co)icavm 

 (nobis), but it is smaller, has the beaks less medial, has larger rays and a less number, 

 the epidermis is more yellow and the cardinal teeth are less compressed. It also ap- 

 proaches in outline and tlie rays to Novi-Ehoraci (nobis), but is not so oblique. The 

 females seem to be much smaller than the males, and have three or four large green 

 rays over the enlarged umbonial slope. I have not seen the soft parts of this specie.s. 

 Three of the specimens bear the enlarged female character in the shell, six that of 

 the form of males. Some of the specimens have more numerous and rather smaller 

 rays, and some of the broad rays are disposed to divide into capillary forms. One of the 

 specimens has the double lateral tooth on the right or reversed side, which is a very 

 rare occurrence, but which I have seen in several other species and have mentioned 

 elsewhere. 



Uxio JoiiANXis. PI. 55, fig. IGS. 



Testa obliquo-ellipticfi, subinflatfi, postiec obtuse' angulatfi, valdu inifiriuilaterali ; valvulis subcrassis, antic^ 

 crassioribus; natibus subelevatis ; epidermide tenebroso-viridi, ad umboncs niicante, posticc luteii ; 

 dentibus cardiiialibus subcrassis, compressis, subercctis; luteralibus curtis, rectis. subcrassis corrugatis- 

 ([ue; margaritil alb;*i et valdo iridescente. 



Shell obliquely elliptical, somewhat inflated, obtusely angular behind and very 

 inequilateral ; valves rather thick, thicker befox'e ; beaks rather elevated ; epidermis 

 dark green, yellow behind, shining on the uinbones; cardinal teeth rather thick, 

 compressed and somewhat erect; lateral teeth short, straight, rather thick and rough ; 

 nacre white and very iridescent. 



Proc. Acad. Xat. Sci. 1859, p. 171. 



Hah. — Connasauga River, Bishop Elliott, and Etowah River, Georgia, Rev. G. 

 White ; Alabama River, Dr. Budd. 



My cal)inet and caljinets of Bishop Elliott, Rev. Mr. White and Dr. Budd. 

 Diam. '5, Length •?, Breadth 1 indi. 



Shell obliquely elliptical, somewhat inflated, olitusely angular behind, rounded 

 before and very inequilateral ; substance of the shell rather thick, much thicker 

 before; beaks rather elevated ; ligament very short, rather thin, light brown; epider- 

 mis dark green, yellow behind, shining on the umbones and striate below, with two 

 or three distant marks of growth ; umbonial slope slightly raised and rounded; pos- 

 terior slope moderately wide, usually bright yellow with two well marked green ra^s 

 on each valve passing from the beaks to the posterior margin ; cardinal teeth rather 

 thick, compressed, .somewhat erect, single in the right and double in the left valve; 

 lateral teeth short, straight, rather thick and rough ; anterior cicatrices distinct, 

 small and well impressed ; ])osterior cicatrices distinct, small and moderately im- 

 pressed ; dorsal cicatrices placed under the \i\ate and behind the cardinal teeth ; cavity 



