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62 ZOOLOGICAL GEOGRAPHY. [part in.
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 southern range of islands, or the Lesser
Antilles, are, almost without exception, volcanic ; beginning with
the small detached volcanoes of Saba and St. Eustatius, 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 all 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 union. Thus, the northern range of Hayti is
continued westward in Cuba, and eastward in Portorico ; while
the south-western peninsula extends in a direct line towards
Jamaica, the depth between them being 600 fathoms. Between
Portorico and Hayti there is only 250 fathoms; while close to
the south of all these islands the sea is enormously deep, from
more than 1,000 fathoms south of Cuba and Jamaica, to 2,000
south of Hayti, and 2,600 fathoms near the south-east extremity
of Portorico. The importance of the division here pointed out
will be seen, when we state, that indigenous mammalia of pecu-
liar genera are found on the western group of islands only;
and it is on these that all the chief peculiarities of Antillian
zoology are developed.
Mammalia.—The mammals of the West Indian Islands are
exceedingly few, but very interesting. Almost all the orders
most characteristic of South America are absent. There are no
monkeys, no carnivora, no edentata. Besides bats, which are
abundant, only two orders are represented ;
rodents, by peculiar
forms of a South American family ; and insectivora (an order
entirely wanting in South America) by a genus belonging to a
family largely developed in Madagascar and found nowhere else.
The early voyagers mention " Coatis " and " Agoutis " as being