59 
cies having almost the shape of Natica. They can- 
_not be confounded with Paludina, because the labium 
is thickened, the duplication uniting above with the 
labrum, and the aperture is also acutely angular 
above. I believe all the species adhere only to cal- 
careous banks or to stones; never travelling in the 
sand like many species of Melania and Paludina. 
ANCULOTUS PRAROSUS. 
Puate VIIIL—-Fig. 13. 
DESCRIPTION. 
Shell suboval, ventricose; spire very short, much 
eroded at the apex; body whorl contracted near the 
middle by a broad slight channel; epidermis horn- 
coloured, with dark angular spots disposed in bands; 
distinct on the interior of the labrum; base deeply 
indented behind the columella; columella angulated 
at base; aperture subovate; acute above. ‘Length 
three-fourths of an inch. — 
Anculotus prerosus, Say. Journal of the Academy 
of Natural Sciences, vol. ii. p. 177. 
OBSERVATIONS, 
Inhabits the Ohio and Tennessee rivers. 
Ihave a variety less ventricose, and without any 
indentation at base. 

