PREFACE. “xi 
The geologist, too, is patiently learning the language of the 
rocks and the drift, written long ages ago, which can alone be 
interpreted by comparing fact with fact, each of which, when 
well authenticated, is a new word in this new language, in 
which Nature tells the story of what once was and the changes 
she has wrought in bringing her works to their present state. 
So must the lessons of all the sciences be studied before they 
can meet the demand for knowledge made by the advancing 
standard set up by the inquiring mind of this our day, which we 
may well anticipate will be greatly elevated in the immediate 
_ future. 
I hope that others may take up other divisions of the subject, 
and treat them so thoroughly as to leave nothing to be desired, 
till at last the whole subject will be so wrought in detail that 
the generalizer will find in his hands abundant material for his 
part of the work. His great want now is well attested facts. 
These I have attempted to give without adornment, as to the 
animals treated. In preparing my illustrations, I have tried to 
make them true to nature, regardless of the question whether 
they were ornamental pictures or not. In the full figures I have 
as far as possible drawn from photographs, taken when the 
animals were standing at ease, believing that in this way I could 
give a truer idea of them than if they were made to assume 
striking and unusual attitudes, which might be more attractive 
to the eye. If my animals differ in position and appear less 
elegant in form than the same animals are generally represented 
in books and in paintings, I can only say that mine are as near 
to nature as I could represent them, without any attempt to im- 
prove upon nature, for so I thought I could be most truthful 
and most instructive. 
I only claim to be an amateur naturalist, wanting that severe 
and systematic study and discipline indispensable to the pro- 
fessional scientist. The labor of my life has been devoted to 
another field, while scientific studies have been my recreation. 
If I have learned how to observe facts, and have clearly stated 
