part at the anterior end, wide, obtuse, well produced obliquely and 

 laterally : labium well thickened, slightly separated from the penult 

 wiiorl. 



]Mean divergence about 12"^: length .G5 inch; greatest breadth .19 

 inch; least breadth .15 inch: length of (he part lost by truncatiou 

 .22 inch. 



Geomelania piiocera. Shell slender, conic-cylindrical : whitish: 

 with, on each whorl, about thirty stout prominent, acute-edged trans- 

 verse ribs, which are continued nearly to the anterior margin of the 

 aperture; with very numerous microscopic lightly impressed spiral 

 stria; in the intercostal spaces : spire with rectilinear outlines : apex 

 truncate with the loss of seven or eight whoids ; whorls remaining 

 seven to seven and one-half, moderately convex, with a well impress- 

 ed suture : aperture ovate, widely and deeply effuse : labrum well 

 expanded, reflected, and thickened ; with the linguifbrra part at the 

 anterior extremity well produced obliquely and downwards, rather 

 narrow, but not acute : labium well thickened, separated sliglitly from 

 the penult whorl. 



T>Iean divergence about 10^; length .G3 inch ; greatest breadth .15 

 inch ; least breadth .13 inch. 



Gko?jelaxia GRACILIS- SlicU similar to that of G. jyrocera ; 

 but the ribs are much more slender and numerous (about forty on 

 each whorl), and are more or less inequidistant ; only very slight traces 

 of spiral strise can be detected under a magnifier : the apex is truncate 

 with the loss of eight whorls : the linguiform part of the lip is sub- 

 acute, and is much produced obliquely and laterally at the lower ex- 

 tremity of the right side : the labium is as thick as the labrum. 



Mean divergence about 10"^ ; length 55 inch ; greatest breadth .13 

 inch; least breadth 11 inch. 



Ynr^ parea is but .35 inch long, and has about thirty-six ribs. 



Geomelania typica. Shell slender, conic : whitish : wuth, on 

 each whorl, about twenty-six to thirty prominent acute-edged trans- 

 verse ribs, which become obsolete only near the anterior extremity ; 

 with very numerous microscopic lightly impressed spiral striie, which 

 <]o not traverse the summits of the ribs : spire with rectilinear out- 

 lines : apex truncate with the loss of seven or eight whoi'ls : whorls 

 remaining about seven, moderately convex, with a well impressed su- 

 ture : aperture ovate, widely and deeply effuse : labrum well expand- 

 ed, moderately thickened ; with the linguiform part at the anterior 

 extremity of the liglit side, excessively produced obliquely, very nai-- 



