ZOOLOGICAL GEOGRAPHY. 131 



north, which never reach South America; so that it is convenient to sepa- 

 rate this district as a sub-region, which forms, to some extent, a transition 

 to the Nearctic region. * * • * :^ ^ >jc 



The West Indian Islands are, in many respects, one of the most inter- 

 esting of zoological sub-regions. In position they form an unbroken chain 

 uniting North and South America, in a line parallel to the great Central 

 American isthmus; yet instead of exhibiting an intermixture of the pro- 

 ductions of Florida and Venezuela, they differ widely from both these 

 countries, possessing in some groups a degree of specialty only to be found 

 elsewhere in islands far removed from any continent. They consist of two 

 very large islands, Cuba and Hayti; two of moderate size, Jamaica and 

 Portorieo; and a chain of much smaller islands, St. Croix, Anguilla, Ear- 

 buda, Antigua, Guadaloupe, Dominica, Martinique, St. Lucia, St. Vincent, 

 Barbadoes and G-renada, with a host of intervening islets. Tobago, Trini- 

 dad, Margarita and Curagao, are situated in shallow water near the coast of 

 South America, of which they form part zoologically. To the north of 

 Cuba and Hayti are the Bahamas, an extensive group of coral reefs and 

 islands, seven hundred miles long, and although very poor in animal life, 

 belonging zoologically to the Antilles. All the larger islands, and most of 

 the smaller ones (except those of coral formation) are very mountainous 

 and rocky, the chains rising to about 8,000 feet in Hayti and Jamaica, and 

 to nearly the same height in Cuba. All, excej)t where they have been 

 cleared by man, are covered with a luxuriant forest vegetation ; the temper- 

 ature is high and uniform; the rains ample; the soil, derived from granitic 

 and limestone rocks, exceedingly fertile; and as the four larger islands to- 

 gether are larger than Great Britain, we might expect an ample and luxu- 

 riant fauna. The reverse is however the case; and there are probably no 

 land areas on the globe, so highly favored by nature in all the essentials for 

 supporting animal life, and at the same time so poor in all the more highly 

 organized groups of animals. Before entering upon our sketch of the main 

 features of this peculiar but limited fauna, it will be well to note a few pe- 

 culiarities in the physical structure of the islands, which have an important 

 bearing on their past history, and will enable us to account for much that 

 is peculiar in the general character of their natural productions. 



If we draw a line immediately south of St. Croix and St. Bartholomew, 

 we shall divide the archipelago into two very different groups. The south, 

 ern range of islands, or the Lesser Antilles, are, almost without exception, 

 volcanic; beginning with the small detached volcanoes of Saba and St. Eus- 

 tatius, and ending with the old volcano of Grenada. Barbuda and Antigua 

 are low islands of tertiary or recent formation, connected with the volcanic 

 islands by a submerged bank at no great depth. The islands to the north 

 and west are none of them volcanic; many are very large, and these have 

 a central nucleus of ancient or granitic rocks. We must also note, that the 

 channels between these islands are not of excessive depth, and that their 

 outlines, as well as the direction of their mountain ranges, point to a former 



