62 UNIVERSAL EVOLUTION 



In the formation of species, by evolution through 

 natural selection, geographical distribution is one of 

 the leading proofs. When variations occur in the off- 

 spring, which enable them to spread out over a larger 

 habitat than that exclusively occupied by the parent 

 stock, if they happen to cross natural barriers, either 

 of mountains, or water, isolation then takes place. 

 There is not then apt to be cohabitation between the 

 parent stock and the variated offspring. In this case 

 the existing species will undoubtedly persist not only 

 by virtue of the isolation alone, but be also greatly 

 assisted by the effect of the new environment of new 

 food, air. climate and all those objective phenomena 

 that act upon the senses. But there seems to have been 

 no new species formed in Australia since the Cretaceous 

 epoch. The fauna of the Cretaceous period therefore 

 persisted. Had it been possible for higher forms of 

 vertebrates (mammals) to invade Australia from Asia, 

 the Cretaceous forms would not have persisted, at least 

 not to a noticeable extent, and such of the marsupials 

 and monotremes as could cross with other forms, would 

 have produced new species. For these reasons Aus- 

 tralian species of animals remained of a lower grade. 



The evidence everywhere shows that it is illogical 

 to conclude that species, anywhere, was specially 

 created. On the contrary, it is evident that organisms 

 everywhere have a close genetic affinity, and spread 

 from locations to other locations, acquiring new char- 

 acters. But when natural barriers existed, such as 

 water, mountains, or deserts, these prevented the 

 natural distribution, and caused the persistence of 

 local forms. Yet in some instances, as in the Gala- 

 pagos islands, some species could cross the water and 

 still live and grow. 



