FOSSIL VERTEBRATES LN THE WEST INDIES. 175 



related to the West Indian species. All this points strongly to 

 Florida as the source, and the Pleistocene as the time of arrival. 



A giant tortoise, new extinct, is found in Cuba. Unlike the 

 terrapin, it is only distantly related to any other tortoises, somewhat 

 nearer to the species of the Galapagos islands than any other. It 

 does not appear to be especially related to any North American tor- 

 toises, except that it may be descended from some primitive species 

 of the Miocene. True tortoises are found in the Pliocene and Pleis- 

 tocene of South America, but are believed to be immigrants from 

 the north. The Galapagos islands affinities suggest that this species 

 may be derived from the unknown Tertiary fauna of Central Amer- 

 ica. But the Cuban species must have been isolated a long time, at 

 least since the beginning of the Pliocene, one would judge from its 

 peculiar specialization. 



The crocodiles of the West Indies are two, one, C. rhomhifer, 

 peculiar to Cuba. The fossil species in Cuba is C. rhombifer, a 

 broad-headed alligator-like form. It is said to be nearly related to 

 the alleged C. morclctii of Central America. The other species, C. 

 americanus, is found in Florida, Mexico, Central America and the 

 west coast of South America as far as Ecuador, and appears to be 

 rather widely distributed in the West Indies. It is probably signifi- 

 cant that this widely distributed species inhabits the salt marshes, 

 whereas the more local C. rhombifer occurs in fresh water. 



The smaller reptiles and amphibians, fresh water fish, and the 

 various groups of invertebrates are much more widely distributed 

 throughout the West Indies. Their distribution and its causes have 

 been extensively discussed by various authors, but unfortunately 

 without giving due weight to two features in which it differs from 

 the mammals and the two groups of large reptiles. 



First that the dispersal of these lower groups on oceanic islands 

 is probably chiefly brought about by storms. The eggs, attached to 

 small debris, or even the adult animals, if small enough, will often 

 be picked up by violent storms, and carried for considerable dis- 

 tances. A cyclonic storm or tornado will sometimes partly empty 

 a shallow pond, carrying the materials a mile or more into the air, 

 the lighter and smaller debris being carried along for a great many 

 miles before it comes to the ground again. On account again of 



