278 bulletin: museum of comparative zoology. 



in extent. Originally, they probably formed part of Central America, 

 and may have been united with Yucatan and Honduras in one extensive 

 tropical land. But their separation from the continent took place at a 

 remote period, and they have since been broken up into numerous islands, 

 which have probably undergone much submergence in recent times. 

 This has led to that poverty of the higher forms of life, combined with 

 the remarkable speciality, which now characterizes them ; while their 

 fauna still preserves a. sufficient resemblance to that of Central America 

 to indicate its origin." Masterly as is the above resume of the status of 

 conditions in the region under discussion, we cannot but doubt that Dr. 

 Wallace would have written somewhat differently had he penned these 

 lines a quarter of a century later. Probably his " West Indian Islands" 

 refer to the Greater Antilles only, and even so, we now know, as already 

 stated, that throughout almost all of these there are two elements in the 

 fauna, Central American and Northeastern South American, which have 

 come to Cuba, Jamaica, Haiti, and Porto Rico by a land connection 

 stretching westward and southeastward. 



Another view resting solely on geological or physiographical evidences 

 is that presented by Dr. E. T. Hill, who conducted investigations on the 

 geographic relations of the West Indies under the auspices of Mr. Agas- 

 siz. In an article published in the " National Geographic Magazine " 

 (May, 1896, 7, p. 181), he concludes with these words: "The Greater 

 Autilles lie aloug the line of east-west corrugations and apparently rep- 

 resent nodes of gr-eater elevation whereby the surfaces of these islands 

 were projected above the waters as islands, which have persisted without 

 continental connection or union with each other since their origin." 



If we accept Mr. Hill's conclusions as he has summed them up in the 

 sentences quoted, it is impossible to account for a West Indian flora and 

 fauna except by riding to death again the old theory of "flotsam and 

 jetsam." Ocean currents and prevailing winds could never have carried 

 Central American types to any of the islands, as they work strongly in 

 an opposing direction. This alone serves to prove the utter impossibility 

 of Hill's conclusion. Even were winds and currents favoring, we know 

 now that the number of types which will withstand a long submersion 

 in sea water is vastly smaller than was once supposed when it was 

 thought that reptiles, amphibians, land molluscs, and in fact almost all 

 orders of animals were carried hither and thither throughout the oceanic 

 areas. This question has been most convincingly discussed by Scliarff, 

 Beddard, Semper, and others. 



Mr. Agassiz has expressed an opinion on this series of relationships in 



