45 
Inliabitant aquatic, ferruginous, with numerous yellowish dots ; 
tentacula dotted and flexuous. Plate 1, fig. 4. 
Resembles the preceding species in its outline, but differs from 
that shell in the remarkable umbilicate appearance of its spire ; it 
is also destitute of those fine parallel raised lines, and is furnished 
with minute strim, 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, 
tig. 45 ; it is very numerous in the Delaware, in company with the 
two preceding shells. Plate 1, fig. 5. 
Grenus Lymnjea. — 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 Linnmus with his Helices^ but they offer charac- 
ters sufficiently distinct, particularly their inhabitants. 
Lymn^a CATASCOPIUM. — Shell thin, horn color, red or black- 
ish ; whorls four or five, the first large, and generally the remainder 
darker and rapidly decreasing to an acute apex, and wrinkled 
across; aperture 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 
