140 



Murnnudogy of the llinialaijas. 



problem, indeed, and the very different conditions of Animal Life, as 

 compared with that of Vegetables, forbade me to anticipate the discovery 

 of laws of distribution in the Animal Kingdom, so definite and circum- 

 scribed as those which Baron Humboldt has established with regard to 

 Plants ; the principle of animality, if I may be allowed the expression, 

 possesses an innate power of adaptation wliich renders Animals in some 

 measure independent of climate, particularly .is compared with Vegeta- 

 bles, and which increases in proportion as we ascend in the scale of life ;, 

 but I felt that if any such laws of geographical distribution prevailed in 

 Zoology, they might naturally be expected to be exhibited most clearly 

 and unequivocally- on a theatre like this, and therefore that the opportu- 

 nity should not be neglected of investigating the circumstances of a. 

 problem which appeared to promise so much scientific interest. 



From the observation just made, viz. that the power which all animals 

 possess, in a greater or less degree, of adapting themselves to different 

 varieties of climate, and of withstanding, uninjured, the effects of tem- 

 peratures foreign to their natural habits, increases in proportion as we 

 ascend from the lower to the higher tribes, it will be seen that the i\Iam- 

 malia — the class which I had undertaken to review—form one of the 

 most unfavom'able groups for the discussion of this important question. 

 Indeed, v/ere it not from their limited powers of locomotion, they 

 would be the very worst of all, because their higli position in the 

 scale of life, and the superior intelligence and resources with which 

 it endows them, necessarily protect them against changes and casualties, 

 which would prove fatal to more simply organized beings ; but, deprived 

 of the powers of flight, ordinary Mammals have not the means of travers- 

 ing the wide deserts and oceans, which separate the habita])le portions of 

 the earth : the nature of their locomotive powers consequently confines 

 them to particular regions ; and, in spite of the more favourable circum- 

 stances of their physical organization, their more varied resources and 

 superior intelligence, they afford better materials for studying the problem 

 of geographical distribution, than the kindred class of Birds, whose. faculty 

 of rapid flight enables tliem to set oceans and deserts equally at defiance, 

 in passing to the most distant quarters of the globe, and, as it were, to 

 choose their own temperature and clim.ate iu the boundless fields of air. 

 Hence it is that the circumstances of the important problem of geographical 

 distribution are le?s favourably presented in Ornithology than in jMam.ma- 

 logy ; but, with this exception, the observation above made holds good 

 throughout all other classes of animals, and the simplest tribes will al- 

 ways be found to present the most certain results. Insulated fami- 

 lies also occasionally occur, which possess peculiar advantages for the 



