Preface 



IX 



In view of these changes, special prominence has been given in this 

 volume to the popular titles of the various species, which are less subject to 

 such emendations, and these alone have been employed in the legends to 

 the plates and text-figures. 



A new feature in the treatment of the group is the large number of 

 forms ranked as sub-species, or races, instead of as full species. The principle 

 of this is that when certain representatives of a genus, or a group of a genus, 

 are more nearly allied to one another than they are to the other members 

 of the same, they are regarded as sub-species. The Asiatic and American 

 wapitis, for instance, are obviously more closely related to one another than 

 they are to the red deer, while the Caspian maral and the North African 

 deer come nearer to the latter than to any other members of the same group. 

 Consequently all the forms of wapiti are classed as geographical races of a 

 single variable and widely spread specific type ; while the European, the 

 Caspian, and the North African red deer are ranked as sub-species of a 

 second. In like manner the numerous modifications of the sambar type 

 show mutual resemblances not shared either by the chital or the para, and 

 all the former are accordingly brigaded under one specific title. Although 

 in some cases such geographical races, or sub-species, may pass imperceptibly 

 into one another, the absence of intergradation is not considered any bar to 

 classing any particular form as a sub-species. Where such sub-species are 

 separated by the ocean, such intergradation must obviously have ceased after 

 the disruption of the land connection between their respective habitats. 



Generic terms are likewise, for the most part, used in a wide sense, 

 although they are frequently split up into minor groups, or sub-genera, 

 which many writers would probably prefer to rank as genera. If, however, 

 genera are used in a more restricted sense we are very apt to lose sight of 

 many broad generalisations. For instance, if Cervus be split up, we lose 

 sight of the fact that all the large brow-antlered deer are essentially an Old 

 World type, with western representatives in the American wapitis. And 



