xii PREFACE. 



and conclusions would have nothing solid to rest on), these may 

 be omitted by the non-scientific reader, or merely noted as a 

 certain number or proportion of peculiar generic types. Many 

 English equivalents to family and generic names are, however, 

 given; and, assisted by these, it is believed that any reader 

 capable of understanding Lyell's "Principles," or Darwin's 

 " Origin," will have no difficulty in following the main argu- 

 ments and appreciating the chief conclusions arrived at in the 

 present work. 



To those who are more interested in facts than in theories, 

 pie book will serve as a kind of dictionary of the geography 

 and affinities of animals. By means of the copious Index, the 

 native country, the systematic position, and the numerical 

 extent of every important and well established genus of land- 

 animal may be at once discovered ; — information now scattered 

 through hundreds of volumes. 



In the difficult matters of synonymy, and the orthography of 

 generic names, I have been guided rather by general utility 

 than by any fixed rules. When I have taken a whole family 

 croup from a modern author of repute, I have generally followed 

 his nomenclature throughout. In other cases, I use the names 

 which are to be found in a majority of modern authors, rather 

 than follow the strict rule of priority in adopting some newly 

 discovered appellation of early date. In orthography I have 

 adopted all such modern emendations as seem coming into 

 general use, and which do not lead to inconvenience ; but where 

 the alteration is such as to completely change the pronunciation 

 and appearance of a well-known word, I have not adopted it. 

 I have also thought it best to preserve the initial letter of well- 

 known and old-established names, for convenience of reference 

 to the Indices of established works. As an example I may refer 

 to Enicurus,—& name which has been in use nearly half a 



