14 NEW SPECIES OF SHELLS. 



rior base of the tentacula; base or foot of the animal dila- 

 ted, oval, obtuse before and behind. 



Found under stones, &c. in moist situations, on the 

 margins of rivers. Like those of the genera Lymncsa and 

 Planorbis this animal possesses the faculty of crawling on 

 the surface of the water, in a reversed position, the shell 

 downward. 



Genus LYMN^A* 



Shells subovate, oblong or somewhat tapering. Aper- 

 ture entire, longitudinally oblong, the right lip circularly 

 joined to the left at the base and folded back on the 

 pillar. 



SPECIES. 



L» columella. Shell thin, fragile, horn-colour; whorls 

 four, longitudinally wrinkled. Spire prorninent, acute. 

 Suture not much impressed. Aperture dilated, ovate. 

 Columella much narrowed near the base, so that the view 

 may be extended from the base almost to the interior apex 

 of the shell. Length seven-tenths of an inch nearly; of the 

 spire one-quarter of an inch. 



Inhabits stagnant waters and miry places. 



Collection of the Academy, ^ 



Animal aquatic, base not so long as the aperture; 

 dusky, with small whitish spots; tentacula broad, pyrami- 

 dal, compressed; eyes small, black, placed at the inner 

 base of the tentacula. 



This species is allied to Z. Catascopium of the Ame- 

 rican edition of Nicholson's Encyclopedia, but the revo- 

 lution of the whorls is more oblique, the shell thinner, die 

 aperture much more dilated, and the columella differently 



