198 ON THE GEOGRAPHICAL 



less to serpents. The places of their habitation are forests, 

 marshes, or even deserts, and these places have never 

 perceived the influence of cultivation. Not multi])lying, 

 except rarely, so as to incommode man, and seeking to 

 ^vithdraw themselves from pursuit, by retiring to the un- 

 cultivated places %vhich serve for their retreat, the war 

 Avhich is made on them is usually only directed against 

 individiuils ; hence, the number of species, as well as of 

 individuals, ought to remain almost at the point fixed by 

 the general law of Nature from the beginning ; and this is 

 one of the facts which it is essential to establish in physi- 

 cal geography. Now, supposing that the animals of which 

 we speak live still in the same places originally assigned 

 to them ; that they still live in the same climate, and 

 under the same conditions, it is evident that they cannot 

 Lave been subject to any change in the course of ages : they 

 present, then, more than any other living creatures, bases 

 to ascertain Avith precision what should be understood by 

 !tl?ccics, by constant varieties, or by varieties produced by 

 local causes, or by climate. The remarks which I throw 

 out will suffice to shew how important is the study of the 

 geographical distribution of reptiles, especially of Ophi- 

 dians, and tlie influence which this study ought to exer- 

 cise on that of the geographical distribution of animals in 

 general, on zoology, on geology, and on physical geogra- 

 phy. 



The geographic distribution of serpents is subject to 

 nearly tlie same laws as that of other reptiles ; that is to 

 say, their number augments considerably towards the 

 torrid zone, while they are but rare in cold regions. It 

 even appears that serpents do not advance as far north- 

 wards as lizards and batrachians, which are probably 

 among the number of the most Avidely distributed reptiles.* 

 The geographic distribution of serpents, ^dewed in relation 

 to different parts of the world,-j- i^resents some interesting 



* [The Translator has seen both frogs and toads in the Orkney Islands, 

 but he never heard an instance of a serpent or a lizard being found in 

 that group of islands, nor yet in Zetland.] 



T I have given above, p. 92, some observations on the nature of the 

 places which serpents inhabit ; but as we do not possess any exact notices 



