1902.] AND ANCIENT GEOGRAPHY. 847 



seen that our material points to a double connection of Cuba and 

 Central America, an older and a younger one, and it is very likely 

 that the one is identical with Simpson's and the other with Hill's. 

 Between them there is a period of subsidence, the maximum of 

 which belongs probably to the Miocene. This agrees with both 

 Hill's 1 and Simpson's views. The upheaval assumed by Hill for 

 the end of the Tertiary and the corresponding connection with the 

 mainland has been indicated previously by Neumayr (1890, p. 

 541), and the same theory is proposed by Spencer. And, further, 

 Simpson also advocates a Postmiocene elevation, which, however, 

 did not result in a connection with Central America. 2 



According to the foregoing, the history of the development of 

 the Central American and West Indian region, as supported by the 

 freshwater Decapods, is the following : 



Central America, the West Indies and the northern margin of South 

 America formed in the Mesozoic period {certainly during Jurassic and 

 Cretaceous) a continental mass {Antillean continent), which was 

 bomided by sea to the north and south. This ccntinent broke up at 

 the end of the Cretaceous, the chief factor in its destruction being the 

 formation of the Caribbean Sea. The northern remnant of this con- 

 tinent, consisting of the Greater Antilles and parts of present Central 

 America, probably remained a unit up to the Eocene. But at the end of 

 the Eocene and during Oligocene and Miocene the connection between 

 the Greater Antilles and the mainland was severed. But it was re- 

 established toward the end of the Tertiary {Pleistocene) and again 

 destroyed in the recent time} 



1 The subsidence of Cuba at the beginning of the Tertiary, mentioned by Hill 

 (I. c, 1895), re f ers to the beginning of the Ctiban Tertiary — that is to say, to 

 deposits including Eocene and Miocene. See Hill, in Amer. Journ. Sei., Vol. 

 48, 1894, p. 201. 



2 T. Wayland Vaughan {Science, January 24, 1902, p. 148) doubts the Pleisto- 

 cene connection of Cuba with the mainland, since the recorded finds of Pleisto- 

 cene Mammals in Cuba are open to discussion, and possibly did not come from 

 this island. But the cases of identical species among the Mollusks, mentioned 

 by Simpson, and the identical species of freshwater crabs discussed here are 

 beyond doubt, and the tendency of the evidence furnished by them is in the same 

 direction as that of the Mammals. We do not believe, however, in a connection 

 of Cuba with North America, but with Central America. (Simpson accepts an 

 Eocene connection with the island of Florida, by way of the Bahamas, which 

 ended in the Miocene.) 



3 This only partly agrees with what we know about the history of Jamaica. 



