gg NKW UMUNIU.T. OF THE 



Shell wiuootli, very transverse, very nmcli compressed, llattened at tlie sides, very 

 inequilateral, angular behind ; valves rather thick; beaks slightly prominent and 

 compressed ; epidermis dark brown, transversely striate ; cardinal teeth rather thick 

 and pointed ; lateral teeth very long and straight, thickened at the end ; nacre white 

 and iridescent. 



Proc. Acad. Nat. Sci., 1857, p. 31. 



Bob. — Dry Creek near Columbus, Georgia. Bishop Elliott. 



My cabinet and cabinet of Bishop Elliott. 

 Diam. -9, Length 1-6, Breadth 3-6 inches. 



Shell smooth, very transverse, elliptic-lanceolate, very much compressed, flattened 

 at the side, very inequilateral, angular behind and obliquely rounded before ; sub- 

 stance of the shell rather thick and somewhat thicker before; beaks slightly 

 prominent, compressed and furnished with a few irregular undulations at the tip ; 

 ligament long and thin ; epidermis dark brown, transversely and deeply striate, sul- 

 cose at the anterior margin, with distant lines of growth and apparently without 

 rays; umbonial slope obtusely angular; cardinal teeth rather thick, pointed, crenulate 

 and disposed to be double in both valves ; lateral teeth very long, straight and much 

 thickened towards the posterior end ; anterior cicatrices distinct and rather deeply 

 impressed, the superior one very large; posterior cicatrices confluent, the inferior one 

 very large ; dorsal cicatrices rather small and placed under the plate posterior to the 

 cardinal tooth ; cavity of the shell shallow and wide ; cavity of the beaks very shallow 

 and rounded ; nacre white and iridescent. 



Soft Parts. — Branchial uterus extended probably the whole width of outer branchia?. 

 In the only specimen received, the ova transferred were not mature and many were 

 yet in the ovarium, so that the leaf of the outer branchiae on each side was only filled two 

 thirds the length and that in the middle portion. The branchial ovisacks do not extend 

 to the lower edge, but leave a border there. Branchice very wide, short, rather thin, 

 the inner ones much the larger, extending below the whole width, free nearly the 

 whole length of abdominal sack. Palpi very large, oblique, angular at the end, 

 united a short distance on the upper posterior edges. Mantle thin, with a broad mar- 

 gin slightly colored at the edge. Branchial opening small, with numerous small 

 brown papillas on the inner edges. Anal opening very small, with numerous very minute 

 papillae on the edges. Super-anal opening very long, united below for a short distance 

 and in the middle for a long distance. Color of the mass whitish, inclined to salmon. 



Remarlcs. — There were three specimens received from Bishop Elliott in alcohol, all 

 being females. It is very near to saggita=formi^, (nobis,) and belongs to the group of 

 which angustaiiis (nobis) may be considered the type. It is more ovate and striate 

 than the former, and is darker in the epidermis, more deeply striate and not so high 

 on the umbonial slope as the latter. It is also disposed to be more white in the 

 nacre than either of them, and appears to be destitute of rays. In the left vah'e the 



