VI PREFACE 



fact, the only one possible interpretation), I offer 

 the present work as a supplement. It will be 

 found to contain proofs of the necessity, the truth, 

 and the value of Darwinism as the foundation 

 for the theory of descent, within a limited field, 

 and is brought down to the most recent- times. 

 Within these limits the work is complete in itself; 

 for although the student of natural history may 

 have become acquainted with interesting fragments 

 of the actual science, still the subject has not 

 before been presented in so comprehensive a 

 manner, or in so convenient a form. 



Together with my special studies of the zoology 

 of the lower animals, I have for many years past 

 felt myself peculiarly attracted by the advance of 

 our knowledge of the Mammalia in their general 

 relation to palaeontology and anthropology. 

 From year to year I have followed this advance 

 with increased interest, and always with a view 

 to the principal questions connected with the 

 domain as a whole. Hence I venture to offer this 

 work to our younger and rising scientists as, I 

 trust, a suggestive introduction to that ' portion 



