214 GENERAL PRINCIPLES OF ZOOLOGY. 



and the Kiivi of New Zealand, the cassowary, and the Dro- 

 mcens noixz Hollandicc. 



(2) Next to the Australian the best circumscribed is 

 the neotropical region, South America, with the adjacent 

 part of Central America. Here we find the area of di-- 

 tribution of the broad-nosed apes, while the small-nosed 

 apes belong to the Old World ; we find the armadilloes, 

 sloths, ant-eaters, opossums exclusively in America ; of 

 birds, the humming-birds, the remarkable Cotingidce, Tana- 

 gridcB, etc. 



The Four Remaining Provinces. The boundaries of the 

 four other provinces are not so easily defined as those 

 hitherto considered. Since North America is connected 

 by a chain of islands with northern Asia, undoubtedly the 

 nearctic and the palaearctic have been subject to an inter- 

 change of forms. Further, in the repeated alteration of 

 the climate of the nearctic and palaearctic regions is fur- 

 nished the possibility that their animal world has mingled 

 on the one side with the neotropical, on the other with the 

 yEthiopian and oriental. In the same way the oriental 

 animal province has lost its sharp demarcation from the 

 Australian, since the continuous chain of Malay Islands 

 renders possible a constant interchange of forms. Yet 

 each of the four provinces named has numerous genera 

 and families peculiar to itself, and is distinguished by the 

 absence of certain living forms. 



(3) The nearctic region has peculiar to it three mam- 

 malian families, the prong-horned ante/ope, the opossums, 

 and the Haplodontcc ; of the group of Amphibia, the Sire- 

 nidcz and Amphinmid<z. The Nearctic is to be distinguished 

 from the nearest related palaearctic region through the 

 crowding in of neotropical forms like the raccoon, opossum, 

 humming-birds, etc. 



(4) The palcearctic region covers the greatest area and 

 consequently abuts upon many other animal provinces. 

 Hence there exist important differences between the vari- 

 ous local faunas, which are conditioned by climate and 

 great distances, but these are explained by the fact that 



