45 



luhabitant aquatic, ferruginous, witli numerous yellowish dots ; 

 tentacula dotted and flexuous. Plate 1, fig. 4. 



Eesembles the preceding species in its outline, but differs from 

 that shell in the remarkable unibilicate appearance of its spire ; it 

 is also destitute of those fine parallel raised lines, and is furnished 

 with minute striae, never visible in P. trivolvis ; the superior part 

 of the lip is more vaulted, and the carina more visible. 



Planorbis parvus. — Shell horn color or blackish ; whorls 

 four, crossed by minute wrinkles ; concave above and beneath, and 

 equally exhibiting the volutions, body generally subcarinate on the 

 margin ; lip rounded, and not vaulted above nor thickened ; mouth 

 within bluish white. Breadth one-fifth of an inch. 



Animal aquatic, brown, tentacula long, filiform, whitish, with a 

 darker central line, tail rounded. 



Probably the same species with that figured by Lister, tab. 139, 

 fig. 45 ; it is very numerous in the Delaware, in company with the 

 two preceding shells. Plate 1, fig. 5. 



Grenus Lymn^a. — Shell subovate, oblong, or somewhat taper- 

 ing. Aperture entire, longitudinally oblong, the right lip joined 

 to the left at the base, and folding back on the pillar. 



Obs. These shells, as well as those of the preceding genus, 

 were placed by Linnaeus with his Helices, but they ofier charac- 

 ters sufficiently distinct, particularly their inhabitants. 



Lymn^a catascopium. — Shell thin, horn color, red or black- 

 ish ; whorls foiu- or five, the first large, and generally the remainder 

 darker and rapidly decreasing to an acute apex, and wrinkled 

 across ; apertui'e large, oval, not three-fourths the length of the 

 shell. Length seven-tenths of an inch, breadth nearly one-half of 

 an inch. 



Inhabitant yellowish, sprinkled with small, often confluent, paler 

 dots ; tentacula two, broad, pyramidal ; eyes black, placed at the 

 base of the tentacula ; tail obtuse, rounded or emarginate, not so 

 long as its shell. Plate 2, fig. 3. 



It is with much hesitation that we adopt a new specific name for 

 this shell, having always heretofore considered it as the same with 

 the L. putris of authors, (which has been, perhaps, mistaken for 

 the Helix limosa of Linne.) As far as we can ascertain, the princi- 

 pal difference appears to be in the more oblique revolution of the 



