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 which 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 



