06 



now and subacute : labium well tliickcnecl, a little reflected and sep- 

 arated from the penult whorl except at the upper extreraitj. 



Mean divernjence about 10'^; length .47 inch; greatest breadth 

 .125 inch; least breadth .11 inch. 



Yixvpygmaea is but .3 inch long. 



Geomelania AFFiNis. Shell similar to that of G. expansa, but 

 the aperture is very deeply effuse anteriorly, and the linguiform part 

 of the lip is excessively produced obliquely, and is narrow : the apex 

 is truncate with the loss of about seven whorls. Dimensions nearly 

 as in G. expansa. 



Geomelania MEDIA. Shell nearly cylindrical : whitish: with, on 

 each whorl, about thirty-five much arcuated prominent acute-edged 

 rather slender transverse ribs : spire with rectilinear outlines : apex 

 truncate with the loss of Avhorls : whorls remaining six, mod- 

 erately convex, with a well impressed suture : aperture ovate, wide- 

 ly effuse : labrum moderately expanded and thickened ; with the lin- 

 guiform part at the anterior extremity of the right side, well produc- 

 ed obliquely, not very narrow, subacute : labium well thickened, sep- 

 arated slightly from the penult whorl except at the upper extremity. 



Mean divergence about ll'^ ; length A inch ; greatest breadth .107 

 inch ; least breadth .1 inch. 



Geomelania vie in a. Shell similar to that of G. minor, with a 

 greater divergence : it is usually thinner : the linguiform part of the 

 lip is excessively produced laterally, and is very wide : the periphery 

 of the last whorl is more angular than in G. minor. 



Geomelania stkiosa. Shell conic-cylindrical: whitish: with, 

 on each whorl, about sixteen very slender somewhat arcuate ribs, and 

 twenty-five to thirty fine spiral striae, which traverse the ribs, but are 

 sometimes obsolete on their summits; spire with rectilinear outlines : 



apex truncate with the loss of whorls: whorls remaining about 



seven, moderately convex, with a deep suture: aperture ovate, wide- 

 ly and deeply effuse : labrum well expanded, reflected, and thicken- 

 ed ; with the linguiform part moderately produced obtusely and ob- 

 liquely at the lower part of the right side : labium well thickened, 

 slightly separated from the penult whorl except at the upper extrem- 

 ity. 



Mean divergence about 10°; length .38 inch; greatest breadth 

 .085 inch : least breadth .08 inch. 



Geomelania costulosa. Shell conic-cylindrical : whitish : with, 

 on each whorl, about forty very slender somewhat arcuated trans 



