20 INTRODUCTORY. [CHAP. 



On the other hand, species with a small distributional area 

 usually belong to small genera, of which they may be the only 

 representatives. Instances of this nature are afforded by the 

 panda (sElurus] and binturong (Arctictis) of the eastern Himalaya, 

 and the parti-coloured bear (^Eluropus] and chiru antelope (Pan- 

 tholops] of the Tibetan plateau. Although such single representa- 

 tives of genera are highly important to the study of distributional 

 zoology, of vastly greater importance are small genera having two 

 or more species living in widely separated areas. Examples of 

 such are to be found among the porcupines of the genus Atherura, 

 of which one species is Malayan and the other two West and 

 Central African ; in the mice of the genus Golunda, with one 

 African and one Indian representative ; and likewise by the tapirs 

 (Tapirus\ of which there is one Malayan, and several tropical 

 American species. These examples of " discontinuous distribu- 

 tion " among genera are of the very highest import to the science ; 

 since they clearly indicate that some of the lands lying between its 

 present disconnected distributional areas must have formerly been 

 the habitat of the genus, and thus enable important conclusions to 

 be drawn as to the former land-connections between such areas. 

 Both in the case of the tapirs and of the brush-tailed porcupines, 

 remains of extinct species have been discovered in the intermediate 

 areas. 



Equally important are families, either large or small, which 

 contain two or more closely allied small genera respectively con- 

 fined to distant areas. As an instance of a large family containing 

 such allied genera, may be cited the Viverridce, among which the 

 true linsangs (Linsangd) are represented by several species from 

 the Eastern Himalaya and the Malayan countries, while the 

 closely-allied Poianais confined to West Africa. The chevrotains 

 (Tragulidee), on the other hand, form a small family with a dis- 

 continuous distribution ; one genus (Tragulus) being now Oriental, 

 while the other (Dorcatheriuni) is West African. Here it is quite 

 evident, of course, that the distributional area of the family must 

 once have been continuous ; and, as a matter of fact, remains of 

 both genera occur in the Pliocene of India, those of the latter being 

 also found in the European Miocene. 



In other families with a discontinuous distribution, as in the 



