PLEUROCERA. Ill 



columella and is of a darker horn-color. One of the specimens is 

 somewhat carinate on the body-whorl, and has a more developed 

 channel. The form of the channel is very like to Melania (^Tr'ypan- 

 ostoma) regularis (nobis) but it is not so cylindrical nor so green. 

 The aperture is about the third of the length of the shell. I name 

 this after Prof. David Christy, Hamilton, Butler Co., Ohio, who col- 

 lected many fine shells in East Tennessee and North Carolina, which 

 he kindly gave to Mr. Clark. — Lea. 



This species may be distinguished from lahiatum principally 

 by its more ponderous proportions and more flattened volutions. 



55. P. labiatum, Lea. 



Trypanostoma labiatum. Lea, Proc. Acad. Xat. Sci., p. 173, 18G2. Jour. Acad. Nat. 

 Sci., V, pt. 3, p. 272, t. 36, f. 84. Obs., ix, p. 94. 



Description. — Shell smooth, acutely conical, rather thick, shining, 



greenish horn-color; spire attenuate, sharp-pointed; sutures regularly 



impressed : whorls about ten, somewhat convex, carinate towards the 



beak, the last rather large ; aperture rather 



° *^ Fig. 210. 



small, rhomboidal, whitish within ; outer lip 



sharp, thickened towards the margin, very 



much dilated and very sinuous ; columella 



whitish, thickened below and much twisted. 



Operculum subovate, dark brown, rather thin, 

 with the polar point near the middle towards 

 the base. 



Habitat. — Big Miami River, Ohio ; J. Clark. 



Diameter, -43 ; length, -98 inch. 



Observations. — A number of these were sent to me some years since, 

 by Mr. Clark. They were supposed to be Melania ncglecta, Anth., 

 but they are not very closely allied to the species which Mr. Anthony 

 sent to me under that name, nor are they like his figure, nor will 

 they answer to his description. This species has a remarkably ex- 

 panded outer lip, unusually thickened inside of the edge. It is nearly 

 allied to Wliitei herein described, but may be distinguished by being 

 not quite so attenuate, having rather more convexity in the whorls, 

 having a larger outer lip and slightly differing in the cut of the open 

 channel at the base. The aperture is tlirec-tenths the length of tlie 

 shell. — Lea. 



