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CHAP. XIV.] 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, beheved 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