360 APPENDIX. 



SUCCINEA. 



1. S. avara. Shell suboval, pale reddish-yellow, subdia- 

 phanous, fragile, covered with an earthy crust ; whorls three, 

 minutely wrinkled ; body whorl very large ; spire small ; 

 aperture large, subovate, about two-thirds of the whole 

 length of the shell. 



Length three-twentieths of an inch. 



Inhabits the North-west Territory. 



This small species of Succinea occurs in humid places, 

 very frequently under stones and near the water. The 

 shell is always completely incrusted with a coating of earth. 

 It may at once be distinguished from either the ovalis or 

 campestris hy its very small size. PL 15, fig. 6. 



2. S. obliqua. Shell oblong-oval, nearly pellucid, pale 

 amber-coloured ; whorls three, very obliquely revolving, 

 distinctly wrinkled; spire a little prominent; aperture 

 suboval, somewhat oblique. 



Length seven-tenths of an inch ; length of the aperture 

 less than half an inch. 



Inhabits Pennsylvania. 



Of this fine species, found in the vicinity of Philadel- 

 phia, many specimens were some time since presented 

 to the Academy Nat. Sc. by Messrs. Hyde and Mason, 

 and we obtained a specimen near the Falls of Niagara. 



It may be at once distinguished from either the ovalis 

 or campestris by the much greater obliquity of the revo- 

 lutions of its whorls. It is very like the Helix joi/^n* of 

 Linn, but it is more than double the size of that species. It 

 may, however, be a variety of that shell. PI. 15, fig. 7. 



