THE FAUNA OF THE PRAIRIES. 
BY J. A. ALLEN. 
ENN 
In an article in a previous number of the NATURALIST, * atten- 
tion was invited to some of the distinctive features of the primi- 
tive flora of the prairies. In the present paper, which forms in 
some measure a sequel to that, will be noticed the more prominent 
peculiarities of the fauna of the same region. f 
The general facies of the fauna of the prairies, as well as of 
the flora, are determined by a few predominating species. The 
diversity of the animal and vegetable life of a given region being 
dependent upon the diversity of its physical. features, one at all 
versed in the general principles of zoological and botanical geog- 
raphy, would hence never anticipate finding on level plains the 
highly varied life one constantly meets with in regions broken by 
mountain chains and valleys. Woodless regions being also far 
less prolific in species than wooded districts, the prairies, with 
their level surface and general absence of timber, hence present 
conditions in a high degree conducive to the production of the 
slightly varied fauna and flora they are found to naturally support. 
On entering upon the prairies from the eastward, a marked 
change is met with in the mammalian fauna. Whilst few of the 
eastern species wholly disappear,{ many of them become re- 
stricted to the narrow belts of woodland that border the streams, 
so that they thus cease to be either prominent or characteristic. 
This is eminently true of the wood-inhabiting Rodents and Car- 
nivora, and also especially so of the bats. On the other hand, a 
few other species, which find their congenial homes in an open 
country, become at once numerously represented, some of them 
being peculiar to the prairies. A marked difference between the 
mammalian life of the prairies and that of the wooded region 
to the eastward thus results. Although the bats are generally 
wide-ranging species, most of those inhabiting the Northeastern 
* Vol. IV, pp. 577-585, December, 1870. 
{ Northern Mlinois, and Central and Western Iowa. 
{See the writer’s “Catalogue of the Mammals of Iowa.” Proc. Bost. Soc. Nat. 
Hist., Vol. XIII, pp. 178-194, January, 1870, 
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