viii PREFACE. 



distribution of an organic type, and to be more clearly influenced 

 by the various known or inferred changes in the organic and 

 physical environment. 



This systematic review of the distribution of families and 

 genera, now forms the last part of my book — Geographical 

 Zoology; but it was nearly the first written, and the copious 

 materials collected for it enabled me to determine the zoo- 

 geographical divisions of the earth (regions and sub-regions) to 

 be adopted. I next drew up tables of the families and genera 

 found in each region and sub-region ; and this afforded a basis 

 for the geographical treatment of the subject — Zoological Geo- 

 graphy — the most novel, and perhaps the most useful and 

 generally interesting part of my work. While this was in progress 

 I found it necessary to make a careful summary of the distribu- 

 tion of extinct Mammalia. This was a difficult task, owing 

 to the great uncertainty that prevails as to the affinities of many 

 of the fossils, and my want of practical acquaintance with 

 Palaeontology; but having carefully examined and combined 

 the works of the best authors, I have given what I believe is 

 the first connected sketch of the relation of extinct Mammalia 

 to the distribution of living groups, and have arrived at some 

 very interesting and suggestive results. 



It will be observed that man is altogether omitted from 

 the series of the animal kingdom as here given, and some ex- 

 planation of this omission may perhaps be required. If the 

 genus Homo had been here treated like all other genera, nothing 

 more than the bare statement — " universally distributed " — 

 could have been given ; — and this would inevitably have pro- 

 voked the criticism that it conveyed no information. If, on the 

 other hand, I had given an outline of the distribution of the 

 varieties or races of man, I should have departed from the plan 

 of my work for no sufficient reason. Anthropology is a science 



