322 ZOOLOGICAL GEOGRAPHY. [part in. 



plains or arid deserts. It hcappens that the three great Old 

 World regions are separated from each other by a debatable land 

 which is chiefly of a desert character ; hence we must expect to 

 find a resemblance between the inhabitants of such districts in 

 ea'^h region. We also find a great resemblance between the aquatic 

 birds of the three regions ; and as we generally give little weight 

 to these in our estimate of the degree of affinity of the faunas of 

 different countries, so we should not count the desert fauna as of 

 equal w^eight with the more restricted and peculiar types which 

 are found in the fertile tracts, — in the mountains and valleys, and 

 especially in the primeval forests. The supposed preponderance 

 of exchisively Ethiopian groups of Mannnalia and Birds in this 

 sub-region, deserves however a close examination, in order to 

 ascertain liow far the facts really warrant such an opinion. 



Mammalia. — The following list of the more important genera 

 of Mammalia which range over the larger part of this sub-region 

 will enable naturalists to form an independent judgment as to 

 the preponderance of Ethiopian, or of Oriental and Palfearctic 

 types, in this, the most important of all the classes of animals 

 for geographical distribution. 



Range of the Genera of Mammalia which Inhabit the Sub-region 



OF HiNDOSTAN. 



