170 



cies of sheep nor of oxen ; no lions roam over 

 its torrid plains ; nor is the elephant, or camel, or 

 hippopotamus of the old world there a denizen. 

 On the contraiy, we meet with there the zama, 

 the tapir, and numerous other quadrupeds, to 

 which the old world affords nothing similar. In 

 New Holland again, we have the kangaroo, a 

 marsupial animal, but quite different from the 

 American opossum, and that singular anomaly 

 the ornithoryncus, which in structure and habits 

 partakes both of the bird and quadruped. So 

 likewise the birds and insects of the American 

 continent are almost totally distinct from those 

 common to the old world, however well adapted 

 we might suppose those winged creatures, to 

 transport themselves into every clime and re- 

 gion. 



We find further, that islands are in general 

 more thinly inhabited than the continents which 

 they nearly adjourn though in these cases the 

 animals are of the same species, for the most 

 part, as those of the neighbouring mainland. In 

 islands far removed from continents, however, 

 the species of animals are generally distinct and 

 peculiar. Of this circumstance New Holland 

 presents us with numerous examples, as well as 

 Java, Sumatra, and the islands in the Chinese 

 seas. 



Now, the question has been started, has the 

 colonization of the earth proceeded from one 

 central point ; or have there been various such 

 points, from which the numerous tribes of ani- 



