CHAP. XIV,] 
THE NEOTROPICAL REGION, 
70 
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 haying 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 Solenodon, 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 
