CHAP. xiv.J THE NEOTROPICAL REGION. 79 



account, is Jamaica ; and taking this as a type of what will 

 probably be found in Cuba and Hayti, we must place the 

 continental period as having occurred after the close of the 

 Miocene, or during some part of the Pliocene epoch, since a large 

 portion of the surface of the former island consists of beds of 

 marine limestone from 2,000 to 3,000 thick, believed to be of 

 Pliocene age. After some time, the land between Hayti and 

 South America subsided, and still later that between Central 

 America and Cuba with Jamaica; but a large tract of land 

 remained insulated, and no doubt supported a very much richer 

 and more varied fauna than now. We have evidence of this in 

 extinct Mammalia of large size, belonging to the peculiar South 

 American family of the chinchillas, which have been found in 

 caves in the small islands of Anguilla, and which, from the 

 character of the land-shells associated with them, are believed to 

 be of Pliocene or Post-pliocene age. This discovery is most 

 interesting, and gives promise of very valuable results from 

 the exploration of the numerous caverns that undoubtedly 

 exist in the abundant limestone strata of the larger islands. 

 This extensive Antillean land, after long continuing undivided, 

 was at length broken up by subsidence into several islands; 

 but as this alone would not account for the almost complete 

 annihilation of the mammalian fauna, it seems probable that 

 the subsidence was continued much farther, so as greatly to 

 reduce the size and increase the number of the islands. This 

 is indicated, by the extensive alluvial plains in Cuba and 

 Hayti, and to a less extent in Jamaica ; and by elevated beds 

 of Post-pliocene marls in the latter island. 



The series of changes now suggested, will account for all the 

 main features of the Antillean fauna in its relations to that of 

 the American continent. There remains the affinity with 

 Madagascar, indicated by Sofmodon, and a few cases of African 

 and Asiatic affinity in insects and land-shells ; but these are far 

 too scanty to call for any attempt at special explanation. Such 

 cases of remote affinity and discontinuous distribution, occur in 

 all the regions, and in almost every group of animals ; and we 

 look upon them almost all, as cases of survival, under favourable 



