*6o NINETEENTH CENTURY. PT. HI. 



only found in particular countries ; kangaroos and pouched 

 animals, for example, in Australia; and sloths and arma- 

 dillos in South America. Now it is remarkable that all the 

 fossil quadrupeds in Australia are also pouched animals, 

 though they are of different kinds and larger in size than 

 those now living ; and in the same way different species of 

 sloths and armadillos are found fossil in South America ; 

 whiie in the rocks of Europe fossil mammalia are found, 

 only slightly different in form from those which are living 

 there now. Naturalists therefore asked themselves again 

 ' Would it not seem likely that the living pouched animals 

 of Australia, and the sloths and armadillos of America are 

 the descendants of the dead ones in the rocks, although 

 they have in the course of long ages become rather different 

 from them ; while oxen, bears, wolves, etc., are also the 

 descendants of those which are found buried in the rocks 

 of Europe?' 



Gradual Succession of Animals which have ap- 

 peared upon the Globe. This seemed still more likely 

 as the study of geology advanced, and it became clear that 

 a gradual succession of higher and higher animals had 

 appeared upon the globe. Thus, in the oldest rocks con- 

 taining fossils, we find no monkeys, no quadrupeds, no rep- 

 tiles, no amphibians such as our frogs, but only shells of 

 marine animals, and a few bones of fishes, of kinds quite 

 different from those now living. 



Then in rocks above these we find the fish becoming 

 very abundant and varied, and higher still we meet with 

 footprints of some animal with feet ; and the bones of an 

 amphibian, somewhat like a frog, are next found. In these 

 times the fish began to cease to be monarchs of the water, 

 for a little higher up huge swimming reptiles, like our 



