62 
ZOOLOGICAL GEOGRAPHY. 
[part III, 
history, and will enable ns 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 
