368 PALAEONTOLOGY AND EVOLUTION XI 



with the following problem whenever it is clearly 

 put before him : Here are the Faunae of the same 

 area during successive epochs. Show good cause 

 for believing either that these Faunae have been 

 derived from one another by gradual modification, 

 or that the Faunae have reached the area in ques- 

 tion by migration from some area in which they 

 have undergone their development. 



I propose to attempt to deal with this problem, 

 so far as it is exemplified by the distribution of 

 the terrestrial Vertebrata, and I shall endeavour 

 to show you that it is capable of solution in a 

 sense entirely favourable to the doctrine of evo- 

 lution. 



I have elsewhere l stated at length the reasons 

 which lead me to recognise four primary distribu- 

 tional provinces for the terrestrial Vertebrata in 

 the present world, namely, first, the Ncvozelanian, 

 or New-Zealand province ; secondly, the Austra- 

 lian province, including Australia, Tasmania, and 

 the Negrito Islands ; thirdly, Austro-Columbia, or 

 South America plus North America as far as 

 Mexico ; and fourthly, the rest of the world, or 

 Arctogcea, in which province America north of 

 Mexico constitutes one sub-province, Africa south 

 of the Sahara a second, Hindostan a third, and the 

 remainder of the Old World a fourth. 



Now the truth which Mr. Darwin perceived and 



1 " On the Classification and Distribution of the Alectoro* 

 morphse ; " Proceedings of the Zoological Society, 1868. 



