PREFACE. 
The present work includes, so far as known, all the living mammals 
which have been found in Illinois and Wisconsin, and gives descriptions 
of the various species and subspecies, with more or less of their life 
histories, together with maps illustrating their supposed geographical 
distribution. To increase its usefulness, brief synopses of all the known 
species and subspecies, belonging to our genera, which occur in eastern 
North America, are given and their distribution is indicated in the maps. 
While it is hoped it will prove a useful book of reference for the 
specialist, it has been written with special regard to the needs of the 
layman, for, without departing from scientific lines, I have endeavored 
to make it as non-technical and popular in character as a serious con- 
sideration of the subject would permit. 
With this object in view, for the purpose of simplifying identifica- 
tion of the various species belonging to a family, they are, wherever 
possible, arranged in the keys in groups based upon external characters 
which may be readily recognized by the lay reader, often regardless of 
their genera and not serially in their proper order as they are treated 
in the text. In a few cases, however, positive identification of a species 
depends upon dental characters which, while usually well-marked, are 
sometimes (as among the Shrews) too small to be seen with the naked 
eye. The student should therefore provide himself with a strong lens 
for the purpose. 
At the present time 94 species and subspecies of mammals have 
been recorded from Illinois and Wisconsin, and probably several more 
will in time be added to the list. Such species as Dyche’s Harvest 
Mouse (Reithrodontomys dychei), Little Meadow Mouse (Microtus 
minor), Woodland Jumping Mouse (Napa@ozapus insignis), Prairie Spot- 
ted Skunk (S'pilogale interrupia), Big-eared Bat (Corynorhinus macrotis) 
and Free-tailed Bat (Nyctinomus depressus), have been taken in 
such nearby localities that there is little doubt that most of them will 
ultimately be found to occur within our limits. 
Those who desire to study our mammals will be interested to learn 
that a considerable number may still be found in a wild state in 
the public parks of Chicago. In Jackson Park alone I have seen the 
following fifteen species: Northern Gray Squirrel, Striped Ground 
I 
