192 bulletin: museum of comparative zoology. 



are identical and differ from the Cuban race, whose affinities are 

 nearer the large Yucatan form. I have already suggested that the 

 occurrence of a small Eptesicus in the Bahamas may be explicable 

 by supposing that it was derived from the small Central American 

 E. propinquus, by way of Jamaica and San Domingo. Further 

 research, however, must establish its presence or absence on these 

 intermediate islands. It may be argued that if this supposed connec- 

 tion allowed certain species to reach the eastern Greater Antilles, 

 independently of a connection by way of Cuba, why did not others, 

 such as Solenodon, Plagiodontia, Erophylla, reach Jamaica by the 

 same route? It is possible that such a movement did take place; 

 but at this date it might be out of the question to determine whether 

 a Jamaican species had come directly from the continent to the west, 

 or from Antillea to the east. Perhaps by this latter route came such 

 now wholly West Indian genera as Monophyllus, Ariteus, and Reith- 

 ronycteris. On the other hand, the main movement would naturally 

 be from the west toward the less thickly populated lands to the east. 

 In conclusion, it appears that the present evidence afforded by the 

 distribution of West Indian mammals in the main corroborates the 

 current hypothesis that the fauna is derived in part from northern 

 South America, and in part, by means of probably at least two land 

 bridges, from North and Central America. A few genera are peculiar, 

 and found throughout the chain. These may represent forms that 

 were formerly wide ranging on the mainland and spread throughout 

 the chain, either from both ends, or from one end provided the present 

 island series was then a continuous land mass; on the other hand 

 they may have developed on an Antillean continent, and since be- 

 come isolated on the several islands through a depression of this 

 continent. To the Greater Antilles, two main land bridges are 

 indicated: one by way of the Yucatan peninsula to Cuba; a second 

 by way of the Honduras peninsula to San Domingo and the Bahamas. 

 Subsidiary connections probably occurred between Cuba and Florida, 

 and Cuba and San Domingo. Between the latter and Jamaica there 

 was doubtless a land connection, as well as between Jamaica and 

 Central America. As shown by Alexander Agassiz in his Three 

 Cruises of the Blake, published in 1888, there is at a comparatively 

 shallow depth a bank connecting Honduras with Swan Island and 

 other islets, Jamaica, and the southwestern arm of San Domingo. 

 The five hundred fathom line would practically include this connec- 

 tion, as well as the islands of Porto Rico, Virgin Islands, and the 

 Bahamas. Between Cuba and San Domingo, however, is a greater 



