CH. I] CROCODILES OF OLD WORLD. 45 



undoubted Crocodile, C. palustris, both conditions may 

 occur. The reduced number of teeth is another indication 

 of the more modern character of the genus Crocodilus. 

 The wide distribution of the genus is indicative of a 

 younger and more vigorous stock, as is also perhaps the 

 larger size of many Crocodiles as compared with Alligators. 

 In Mr Boulenger's catalogue the measurement of no 

 Alligator is stated to exceed 4£ metres, and they are 

 generally much smaller than this ;-on the other hand the 

 Crocodile of Madagascar is said to reach a length of 

 thirty feet, and generally the Crocodiles are large. If 

 this view respecting the geographical and structural 

 relations to the Crocodilia be the correct one it is 

 significant that in this case as in so many others the 

 archaic forms have chiefly gravitated towards South 

 America. 



The bearing of the facts in the distribution of this 

 order upon the generally recognised zoo-geographical 

 regions seems to comply with a primary division of the 

 earth's surface into Palseogaea and Neogaea; there is 

 apparently less difference between the Oriental and 

 Australian regions than between either of them and the 

 Ethiopian, though the difference here is but slight. 

 The fact that Crocodiles can traverse the sea is 

 perhaps partly responsible for the absence of peculiar 

 types in the Australian continent, which is connected 

 with Asia by so many intervening islands. It is also 

 perhaps a testimony to the age of the group as contrasted 

 for example with the more modern mammals and birds. 



