l06 PHILOSOPHY OF ZOOLOGY. 



upon die slightest alteration taking place in their physical 

 condition. AVith others, tlie case is very different, and 

 these we can easily naturalise. They can accommodate 

 themselves to a variety of new conditions, and successfully 

 resist the destructive tendency of the changes to which we 

 subject them. 



The change in the condition of the animals we wish to 

 naturalise, should, in all cases, be brought about as slowly 

 as circumstances may permit. In this manner, the first 

 counteracting effects of the system grow into organical ha- 

 bits, before all the evils of the situation are experienced, in 

 which they are destined ultimately to reside. In this gra- 

 dual manner, man has become fitted to reside in every cli- 

 mate, as well as many of the animals which he has re- 

 claimed. 



The details into which we have entered, concerning the 

 distribution of animals, serve to point out the proper me- 

 thod of constructing a Fauna of a particular country. 

 Among British writers, at least, little or no attention is paid 

 to the geographical distribution of the species. In the list 

 of native mnmals, may be found those species which really 

 live in the country, associated with such as visit it periodi- 

 cally, or only at irregular intervals, and with those which 

 have been extirpated, or which have become extinct, and 

 such as have been naturalised. In consequence of this in- 

 congruous assemblage of species, it is difficult to form a 

 correct view of the number or characters of our native ani- 

 mals. Were we to classify them under the following divi- 

 sions, much ambiguity and even error would be avoided. 



1. Resident Animals. — Those animals, only, ought to be 

 considered as the genuine inhabitants of the country, which 

 continue in it the whole year, and can accommodate them- 



