210 GEOGRAPHICAL DISTRIBUTION OF ORGANISMS. 



may have come into existence in any part of it, to spread into 

 the two continents alike the same bear, nearly the same 

 ruminants, and so forth ; but, if the Southern Ocean have 

 possessed, as is likely from its distance, a different develop- 

 ment of animal life from the Northern, and be supposed as 

 sending off terrestrial animals in like manner into South 

 America, the interposition of several great zones of different 

 climate stands forth as a sufficient reason why there should 

 not have been the same communication of zoological forms in 

 that case to the hyperborean seas, as there was from those 

 laving North America to those which dash upon Scandinavia, 

 Russia, and Siberia. 



The hypothesis is equally applicable to the imperfect de- 

 velopments of li/e upon the more recently raised lands, such 

 as the Galapagos islands and Australia. Development is a 

 matter of time, and in the case of these regions, the full time 

 has not yet elapsed. It is therefore exactly what we might 

 expect, upon the natural hypothesis, that, in these regions, ani- 

 mal life should have yet hardly reached the mammalian stage, 

 the point which was attained in our elder and greater province 

 about the time of the oolite. ( 84 ) But no rational cause for 

 this imperfect zoological show can be presented in consonance 

 with the plan of special exertions. Its advocates can only 

 refer to some vague assumption regarding the Divine will, to 

 which it is treason against judgment to come, while a single 

 surmise of natural procedure remains unexhausted. 



