GO CLASS GASTEROPODA. 
and greenish shell is marked with two or three longitudinal 
bands, and which abounds in stagnant waters in France, pro- 
duces living young ones: in the spring of the year they may 
be found in the oviduct of the female, in every stage of de- 
velopment. Spallanzani assures us, that if the young ones be 
taken at the moment of their birth, and be reared separately, 
they will reproduce without fecundation, like those of the 
aphis. The males, however, are nearly as common as the 
females: they have a large penis, which protrudes and 
retracts, as in helix, but through a hole pierced in the right 
tentaculum, a circumstance which renders that tentaculum 
_ apparently larger than the other, and which furnishes us with 
a mode of recognizing the male. 
Add Cyclost. achatinum, Drap.i. 18, &c. 
The ocean produces some shells which differ only from the 
paludine in being thick. They form the 
LITTORINA, Féruss., 
Of which the common species, Le vigneau (Turbo littoreus, 
L.), Chemn. V. clxxxv. 1852, abounds on the coast of France, 
where it is eaten. The shell is round, brown, and longitudi- 
nally streaked with blackish. 
Monopon, Lam., 
Only differs from littorina in having a blunt and slightly salient 
tooth at the base of the columella, which sometimes also has 
a fine notch; the external edge of the aperture is crenulated 
in several species. The animal is more highly ornamented, 
and is generally furnished with three or four filaments on each 
side, as long as its tentacula; the eyes are planted on parti- 
cular pedicles, at the external base of the tentacula; the oper- 
culum is round and horny. 
A small species, the Trochus tesselatus, L., Adanson, Seneg. 
XII. 1; List. 642. 33, 34, with a brown shell, spotted with 
