38 
MOLLUSCA. 
iiicr6ase of the whorls ot their shell, the convolutions of which aie 
nearly in one plane, and because the aperture is wider than it is high. 
It contains an animal with long, thin, filiform tentacula, at the inner 
base of which are the eyes, and from the margin of whose mantle 
exudes a quantity of a red fluid, which is not, however, its blood. Its 
stomach is muscular and its food vegetable, like that of the Limneei, 
of which, in all our stagnant waters, it it the faithful companion. The 
Lijin^us, Lam* 
Separated from the Bulimi of Brugiere by M. Delaniark, have, like a 
Bulimi, an oblong spire and the aperture higher than it is wide; but 
the margin, like that of a Succinea, is not reflected, and there is a 
longitudinal fold in the columella, which runs obliquely into the 
cavity. The shell is thick ; the animal has two compressed, broad, 
triangular tentacula, near the base of whose inner edge are the eyes. 
They feed on plants and seeds, and their stomach is a very muscular 
gizzard, preceded by a crop. Like all the Pulmonea, they are her- 
maphrodites, and the female organ of generation being far from the 
other, they are compelled so to copulate, that the individual which acts 
as a male for one, serves as a female, for a third ; long strings of them 
may be observed in this position. 
They inhabit stagnant waters in great numbers ; they also abound 
with the Planorbes in certain layers of marl or calcareous strata, 
which they evidently prove were deposited in fresh waterf. 
Physa, Drop. 
The Physfe, which were placed without any just motive among the 
Bullae, have a shell very similar to that of a Lymnaea, but without the 
fold in the columella and reflected edge, and very thin. When the 
animal swims or crawls, it covers its shell with the two notched lobes 
of its mantle, and has two long, slender and pointed tentacula, on the 
greatly enlarged internal base of which are the eyes. These are the 
small mollusca of our fountains. 
One of them. Bulla f ontinalis , L., which is sinistral, is found 
in France j;. 
According to the observations of Van Hasselt, we should place 
here the 
ScARAB^us, Montf. 
Which has an oval shell, the aperture narrowed by projecting and 
stout dentations on the side next to the columella, as well as toAvards 
* Hel. stagnalis, L. of which ll.fmgilis is a variety ; — H.pahtsfris ; — H . jieregra ; 
— II. limosa ; — H. auricularia. See Drap., pi. ii, f. 28, 42, and pi. iii. f. 1, 7. 
-f- The mantle of the Limn, glufinosus, like that of the Physse, is sufficiently ample 
to envelope its shell. It is the genus Amphipeplea. Nilsoii, Moll, siicc. 
X The neighbouring species. Bull, hypnorum, L., and Physa acuta, and Scalunginum, 
Drap., require an examination of their aninials. Vide, Drap.,- p. 54, et scq. 
