8 
ANIMALS OP NORTH AMERICA. 
species, generating fresh ones in their turn, and terminating 
with the human family as the masterpiece of this successive 
formation. 
The most natural supposition is, that the all-wise Creator 
placed each species where it was permanently destined to 
live ; and that from these different u centres of creation,” 
combinations have so multiplied between contiguous regions, 
as to form the various races of animal life. When we find a 
country possessing a group or groups of animals not found 
elsewhere, we may at once set down that as being the centre 
of a peculiar creation. In the location of many species, 
nature has placed various limits, and the spaces occupied by 
them are most unequal. For example: the Kangaroo and 
Ornithorhyncus are confined to New Holland ; the Grizzly 
Bear to the Rocky Mountains ; the Dodo, now extinct, to 
the Mauritius ; whilst the Swallow, the Crow, and the Fox, 
extend to every known region. The principal cause of 
“ limitation ” is doubtless connected with the unequal tem- 
perature of localities ; certain species which thrive in one 
climate, perishing under the influence of another ; — also the 
nature of vegetation in one country, and the absence of it in 
another, — as in the Polar regions, — confining to the former 
the larger beasts of prey, dependent on herbivorous animals 
as their food, with the exception of, in the latter, those that 
subsist on fish. The number of species- increase as we near 
the tropics, and there it is where Nature has been most 
lavish in the diversity of life, beauty of color, strangeness 
of form, and greatness of proportion. The present total 
number of living species which has been satisfactorily made 
out and ascertained, exceeds, according to Agassiz, 50,000 ! 
If the time ever comes when the facts of Natural History 
are given without the admixture of fable, then this branch of 
science will be more readily advanced in improvement than 
can be readily hoped for, so long as imagination is allowed to 
take the place of actual observation. Modern writers continue 
