MAMMALOGY OF THE HIMALAYAS. lvii 
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 traversing the wide deserts and oceans, which separate the habitable portions of the earth: the 
nature of their locomotive powers consequently confines them to particular regions; and, in spite of the 
more favourable circumstances 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 them 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 climate in the boundless fields of air. Hence it is that the circumstances of the impor- 
tant problem of geographical distribution are less favourably presented in Ornithology than in Mamma- 
logy ; but, with this exception, the observation above made holds good throughout all other classes of 
animals, and the simplest tribes will always be found to present the most certain results. Insulated 
families also occasionally occur, which possess peculiar advantages for the prosecution of this inquiry ; 
as, for instance, in the case of fresh-water Fishes, than which I am acquainted with no other group of 
animals so well calculated to illustrate the laws of geographical distribution, or so likely to repay a 
careful study under this point of view; and I am only surprised that no competent Ichthyologist has 
hitherto occupied himself with so promising an inquiry. 
The only other principle which can well be regarded as influencing the geographical distribution of 
Animals, viz. the dispersion of Plants, upon which all Animals live, either mediately or immediately, 
is obviously subordinate to that of climate, with which it has been shown to be most intimately 
connected. On a limited scale the distribution of particular species may be seriously affected by the 
influence which civilization and cultivation produce upon the face of particular countries; wild animals 
necessarily disappear with the woods and forests which afforded them food and shelter; the Wolf, the 
Bear, and the Beaver, have thus disappeared from our own country ; the Capercalzie, exterminated about 
a century ago, is once more spreading rapidly over the pine forests of Scotland; but these are partial 
cases, which do not bear upon the general problem of geographical distribution ; and it is obvious, that 
upon the great theatre of nature, climate and temperature are the only laws which regulate it, limited, 
indeed, by the physical structure of the animals, as has been already observed, and by their powers of 
transporting themselves to distant regions. Hence it is that terrestrial and fresh-water tribes are more 
favourable for this study than marine or pelagic; though even among the latter, the comparative 
simplicity of their structure, and their consequent susceptibility of changes in temperature, render the 
habitats of different genera and species more definite and confined than might otherwise be expected. 
Of the former, again, land and fresh-water Mollusks being among the most simply organized, are conse- 
quently most limited in point of range; the species of Insects are almost equally confined, unless in : 
the case of certain tribes, which are susceptible of being transported to distant countries in wood and 
other extraneous substances; next follow Reptiles and fresh-water Fishes; and, last of all, Birds and 
Mammals; the former, as already observed, having an almost unlimited range of habitat, from the faci- 
lities which they derive from their powers of flight, of passing to the most distant quarters of the globe. 
The common Sparrow, the Snipe, and the Woodcock, for instance, are found in the Himalayas and in 
Japan, as well as in the North of Europe; nature has endowed these birds with means of traversing the 
arid climes and extensive deserts which intervene between these localities, which she has denied to i 
Quadrupeds ; and hence we must not expect to find the Badger and the Fox so widely distributed as z eo a 
the Owl and the wild Goose. But if the same species of Mammals are confined to particular regions, 
the great question still remains, whether similar regions, wherever situated, or however separated from . S | 
one another by intervening seas and deserts sence me or analogous fie and it : 
