CUVIER. 



1. Lower jaw of Wombat, showing the ' inflected ' angle of the jaw. 



2. Pelvis of a Kangaroo, showing the ' marsupial bones ' (m). 



which not only were teeth present, but the faces of the 

 neck-vertebrae were cupped, as they are in fishes, instead 

 of being saddle-shaped as they are in normal birds. Again, 

 in all living animals in which hollow bones filled with air 

 are present, the skin is furnished with feathers ; but the 

 extinct Pterodactyles, or flying reptiles, possessed hollow 

 bones, while there is no reason to think that their skin was 

 feathered. 



In the second place, when we have to deal with fossil 

 organisms, we may easily assume that a particular structure 

 was absent in an animal, whereas it might have been 

 present, and yet might not have been preserved, owing 

 to its only having been present in a condition incapable 

 of preservation in the fossil condition. Thus Marsupial 



