HABITUDES. 
97 
or leaves, sometimes lost among mosses, lichens, or other 
parasitic plants. Many species are pleased with swampy 
places, because there they find an abundant subsistence 
suitable to their wants. Others frequent the vicinity of 
fresh waters, which afford them the means of subsistence, 
and a protection against the pursuit of their enemies ; but 
these same species are sometimes found far from humid 
places, sometimes extended on a dry soil clothed with burnt 
up vegetation, and sometimes suspended from the branches 
of trees. The number of serpents wdiich pass all their life 
in water is very small ; and this mode of existence is espe- 
cially natural to sea-serpents, which in vast shoals inhabit 
the most remote regions of our globe. Several species of 
serpents dig for themselves holes, which they never quit 
but to satisfy their wants ; others establish themselves in 
the dens of small mammifera, which they sometimes drive 
out ; some seek an asylum in the holes of trees, under 
their roots, near habitations, or even in houses, where 
sometimes a mass of dunghill or of dried leaves serves for 
their refuge ; others make choice of fields or cultivated 
places, to give chase to the insects or small mollusca that 
abound in such places. 
These observations demonstrate that many serpents 
prefer certain places only because they afford them sub- 
sistence, or because they unite all the conditions neces- 
sary to their existence. Thus, serpents are seen to desert 
their ordinary place of habitation when it ceases to fur- 
nish the means of subsistence. It is true, that this may 
perhaps be applied, with certain modifications, to all ani- 
mals ; but with this difference, that reptiles attached to the 
spot which gave them birth, do not understand how to 
undertake those long migrations which astonish us in birds 
and some mammifera. Most frequently land-snakes wander 
but a little way from where they are located, and we 
almost always find them so near their retreat, that they 
can gain it on the first approach of danger. 
Many snakes live in society, and it appears that they do 
not mutually attack each other; such are most of the 
aquatic species, some of the genus Coluber, and notably 
I 
