FRESH-WATER FISHES AND WEST INDIAN 

 ZOOGEOGRAPHY 



By George S. Myers 

 Stanford University 



[With 3 plates] 

 INTRODUCTION 



Since time immemorial man has enjoyed looldng backward, but it 

 is only within the last century that the researches of the geologist 

 and paleontologist have allowed him to see the earth as it was before 

 he himself existed. Nowadays the strange creatures that peopled the 

 past even appear in the Sunday supplements and the cinema, and 

 the fact that what is now dry land may have been under the sea is 

 common knowledge. To the student of plant and animal distribu- 

 tion, or biogeography, the long-gone past is of particular interest. 

 We know that many living things could not be found where they are 

 if the land and sea had always been exactly as they exist today, and 

 only a study of paleogeography, or the geography of ancient times, 

 will enable us to understand how plants and animals moved about 

 over the face of the earth and reached the places where we now find 

 their living descendants. 



Students of both phytogcography, or plant distribution, and zoo- 

 geography, or animal distribution, must depend largely on the geolo- 

 gist to tell them how the land and sea were bounded in the past, 

 but often they can help the geologist in this very matter. Studies of 

 the relationships of living things, both recent and fossil, frequently 

 point out that two islands or continents must have been connected 

 by dry land at a certain geological time, for example the connection 

 of Alaska with Siberia across Bering Strait. In the same way the 

 close relationship or identity of various species of fishes and other 

 marine animals on the Pacific and Atlantic coasts of Panama show 

 that the two oceans were once connected over what is now the isthmus, 

 and at no very distant period, geologically speaking. In fact, the 

 geologist often depends to a considerable extent on the fossil remains 

 of once-living creatures for information about his rock formations, 

 their age and the climatic and other conditions under which they 



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