390 NEW EXOTIC UNIONIDJE. 



prominent, with rugose and divergent undulations at the tips ; epidermis polished, 

 brownish-green, striate and radiate ; cardinal teeth rather small, compressed, ob- 

 lique ; lateral teeth rather long and curved ; nacre bluish-white and iridescent. 



Hab. — Uruguay River, South America, Prof. J. Wyman. 



My cabinet and cabirfet of C. M. Wheatley. 

 Diam. -6, Length 1-1, Breadth 1*8 inch. 



Shell smooth, elliptical, somewhat inflated, very inequilateral, subrotund behind and 

 round before ; substance of the shell rather thin, slightly thicker before ; beaks 

 somewhat prominent, with large rugose divergent undulations at the tips; ligament 

 rather long, thin and light-brown ; epidermis polished, brownish-green, finely striate, 

 radiate, with distant brown marks of growth ; umbonial slope slightly raised and 

 rounded; posterior slope rather compressed, elliptical, with a raised line on each 

 valve from the beak to the posterior margin ; cardinal teeth rather small, com- 

 pressed, oblique, double in both valves ; lateral teeth rather long and curved ; an- 

 terior cicatrices rather small, well impressed, confluent with the lower, but distinct 

 from the upper; posterior cicatrices confluent, rather large and very slightly im- 

 pressed ; dorsal cicatrices well impressed and placed across the cavity of the beaks ; 

 cavity of the shell rather deep and wide; cavity of the beaks very shallow and 

 rounded ; nacre bluish white and iridescent. 



Remarks. — Three specimens are before me. This species belongs to the group of 

 which atratus (Niaa, Swain.), from Chili, may be considered the type. It is, how- 

 ever, a smaller species, rather more transverse and somewhat thicker. It very 

 closely resembles it in the color of the epidermis and the nacre, and form of the teeth, 

 There is a marked difference, however, in the divergent undulations of the beaks, 

 which in atratus are small and rather delicate, while in lepidus they are rather 

 large, long and more numerous. In all the three specimens the posterior half is 

 dark-green, caused by closely-set rays, the anterior half having but a few indistinct 

 rays over a yellowish ground. 



Anodonta Wymanii. PI. 44, fig. 294. 



Testa lsevi, elliptica, subinflata, inEequilaterali, posticc subbiangulata, antice regulariter rotundata ; val- 

 vulis crassis, antice aliquanto crassioribus ; natibus proniinulis, ad apices aequis; epidermide cinno- 

 rnomea, vel eradiata vel obsolete radiata ; rnargarita rosea et valde iridescente. 



Shell smooth, elliptical, somewhat inflated, inequilateral, subbiangular behind, 

 regularly rounded before ; valves thick, somewhat thicker before ; beaks slightly 

 prominent, smooth at the tips ; epidermis cinnamon-red, without rays, or obscurely 

 rayed ; nacre rose-colored and very iridescent. 



Hab. — Uruguay River, South America, Prof. J. Wyman. 



My cabinet and cabinet of C. M. Wheatley. 



