650 MANUAL OF ZOOLOGY. 



Rhinoceroses, and Hippopotami, then as now, are characteristic 

 Old World forms. The Ruminants are equally characteristic 

 of the eastern hemisphere, though not exclusively confined to 

 it, and they have numerous and varied representatives in later 

 Tertiary deposits. The Giraffe is represented by the Hellado- 

 therium, and the Bactrian Camel by the Merycotherium of the 

 Siberian Drift. The fossil Quadrumana, too, of Europe, all 

 belong to the Catarhine section of the order. 



It is unnecessary to pursue the subject further, but no law 

 is more firmly established than this : " That with extinct as 

 with existing Mammalia, particular forms were assigned to 

 particular provinces ; and that the same forms were restricted 

 to the same provinces at a former geological period as they 

 are at the present day " (Owen). It is to be borne in mind, 

 however, that the law, as just stated, holds good for the later 

 Tertiary period only, and does not apply, in any manner that 

 admits of being traced, to the earlier geological epochs. 



TABULAR VIEW OF THE CHIEF SUBDIVISIONS 

 OF THE SUB-KINGDOM VERTEBRATA. 



SUB-KINGDOM VI. VERTEBRATA. 

 CLASS I. PISCES. 



Order i. Pharyngobranchii. 



2. Marsipobranchii. 



3. Teleostei. 



4. Ganoidei. 



5. Elasmobranchii. 



6. Dipnoi. 

 CLASS II. AMPHIBIA. 



Order i. Labyrinthodontia. 



2. Ophiomorpha. 



3. Urodela. 



4. Anoura. 

 CLASS III. REPTILIA. 



Order i. Chelonia. 



2. Ophidia. 



3. Lacertilia. 



4. Crocodilia. 



5. Ichthyopterygia. 



6. Sauropterygia. 



7. Anomodontia. 



8. Pterosauria. 



9. Deinosauria. 



