PLEUROCERA. 133 



somewhat convex, the last somewhat constricted; aperture small, 

 constricted, rbomboidal, wliitish within; outer lip acute, sinuous; 

 columella thickened below and twisted. 



Habitat. — Cincinnati, Ohio; T. G. Lea. 



Diameter, -33; length, -70 inch. 



Observations. — Among a large number of young Melania (Trypa- 

 nostoma) cauaJicuIata and conica, Say, sent by my brother, long since, 

 I found eight specimens of this small species. All seem to be full 

 grown and are very nearly of the same size. They may be 

 at once distinguished from canalicidata by their being much 

 smaller, beiug much more narrow and having no channel or 

 furrow ou tlie middle of the whorl. The aperture is also 

 much smaller. It differs entii'ely from conica in the whorls, 

 which regularly decrease to the apex, while in that species 

 they decrease rapidly to the apex, which is sharp-pointed. 

 The aperture is about one-third the length of the shell. None of 

 these specimens have bands ; one is slightly brownish inside towards 

 the base. This is very different from Mr. Say's Melania simplex. — 

 Lea. 



The figure is a copy of that given by Mr. Lea. 



78. P. turgidum, Lea. 



Melania fiir^iV/d, Lea, Philos. Proc. ii, p. 82, Oct., 1841. Philos. Trans, ix, p. 18. 

 Wheatley, Cat. Shells U. S., p. 27. Bixnev, Check List, No. 278. Brot, List, 

 p. 33. 



Description. — Shell smooth, obtusely conical, inflated, thick, banded; 

 spire short, pointed at the apex; sutures slightly impressed; whorls 

 seven, flattened; aperture small, trapezoidal; columella thickened, 

 white. 



Habitat. — Holston River, East Tennessee.. 



Diameter, -35 ; length, -55 inch. 



Observations. — This is a very short and thick species, having a very 

 large body-whorl disposed to be obtusely angular at the middle. The 

 number of bands varies. One of the specimens has a single one, 

 another has two bands, and five have five bands, there being seven 

 specimens before me. That with a single band is of a bright yellow; 

 the others are of a greenish-yellow. The aperture is nearly one-half 

 the length of the shell, and twisted at the base.— Lea. 



