INTRODUCTION 
AN apology seems hardly necessary for the issue of this 
book, for any one who takes any interest in Nature 
feels the need of a book treating of the local species of animals 
or plants, and such a book is entirely wanting for Colorado 
mammals. Whatever information we have concerning these 
is scattered through many and various publications, mostly 
issued by the Government, and which are often out of 
print or inaccessible to the average student. 
A few words of acknowledgment and explanation with 
regard to the work on this book will not be amiss. Some three 
years ago, Mr. William Lutley Sclater, then Director of the 
Museum of Colorado College, began a book on the mammals 
of Colorado, but dropped it to take up other work. A little 
later he turned his manuscript over to me with the urgent 
solicitation that I take it up and complete it. Between the 
time when Mr. Sclater began and I took hold, a number of 
species had been added to the Colorado fauna, and as more 
specimens were available from which to draw up the descrip- 
tions, it was necessary to rewrite most of the portion which 
was at that time prepared, as well as to compose the remainder. 
But during all the time I was at work on this I had the willing 
and unfailing advice of Mr. Sclater, and he was also good 
enough to write the diagnoses of the orders, families, and 
many of the genera, and also drew up the keys of the families 
and genera, and he likewise read over and revised the whole 
manuscript. I cannot express how much I owe to him, but 
I would hardly have ventured upon the work without his 
assistance and co-operation. 
XV 
