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66 ZOOLOGICAL GEOGRAPHY. [part m.
ductiveness, but this is, no doubt, partly due to our knowledge
of Cuba and Jamaica being much more complete than of
Havti. The species of resident land-birds at present known are
as follows :
Cuba 68 species of which 40 are peculiar to it.
Hayti 40 „ „ 17
Jamaica 67 „ „ 41 „ „
Portorico 40 „ „ 15
„ „
Lesser Antilles 45 „ „ 24 „ „
If we count the peculiar genera of each island, and reckon
as (|) when a genus is common to two islands only, the
numbers are as follows :— Cuba 7|, Hayti 3|, Jamaica 8|,
Portorico 1, Lesser Antilles 3|. These figures show us, that
although Jamaica is one of the smaller and the most isolated of
the four chief islands, it yet stands in the first rank, both for the
number of its species and of its peculiar forms of birds,—and
although this superiority may be in part due to its having been
more investigated, it is probably not wholly so, since Cuba has also
been well explored. This fact indicates, that the West Indian
islands have undergone great changes, and that they were not
peopled by immigration from surrounding countries while in
the condition we now see them ; for in that case the smaller
and more remote islands would be very much poorer, while
Cuba, which is not only the largest, but nearest to the mainland
in two directions, would be immensely richer, just as it really
is in migratory birds.
The number of birds common to the four larger islands is
very small— probably not more than half a dozen ;
between 20
arid 30 are common to some two of the islands (counting the
Lesser Antilles as one island) and a few to three ; but the great
mass of the species (at least 140) are confined each to some one
of the five islands or groups we have indicated. This is an amount
of isolation and speciality, probably not to be equalled else-
where, and which must have required a remarkable series of
physical changes to bring about. What those changes probably
were, we shall be in a better position to consider when we have
completed our survey of the various classes of land animals.