422 NINETEENTH CENTURY. FT. HI. 



like a fish, a lizard, and a bird, and have at first parts which 

 it loses as it grows into its own peculiar form ? 



Living Animals of a Country agree with the Fossil 

 ones. These were facts entirely belonging to living creatures, 

 but now others sprang up about fossil species which were 

 equally puzzling. We know that certain animals are only 

 found in particular countries ; kangaroos and pouched ani- 

 mals, for example, in Australia ; and sloths and armadillos 

 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 ; while 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 descen- 

 dants 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, &c., are also the descendants of 

 those which are found buried in the rocks of Europe ? 



Gradual succession of Animals which have appeared 

 upon the Globe. This seemed still more likely as the study 

 of geology advanced, and it became clear that a gradual suc- 

 cession of higher and higher animals had appeared upon the 

 globe. Thus, in the oldest rocks containing fossils, we find no 

 monkeys, no quadrupeds, no reptiles, 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 



