pears to be a comparatively steep descent all
round to the average depth of that portion of the Pacific, between 2,000
and 3,000 fathoms. {276}

[Illustration: MAP OF THE GALAPAGOS AND ADJACENT COASTS OF SOUTH AMERICA.]

The light tint shows where the sea is less than 1,000 fathoms deep.
The figures show the depth in fathoms.

The whole group occupies a space of about 300 by 200 miles. It consists of
five large and twelve small islands; the largest (Albemarle Island) being
about eighty miles long and of very irregular shape, while the four next in
importance--Chatham, Indefatigable, James, and Narborough Islands, are each
about twenty-five or thirty miles {277} long, and of a rounded or elongate
form. The whole are entirely volcanic, and in the western islands there are
numerous active volcanoes. Unlike the other groups of islands we have been
considering, these are situated in a comparatively calm sea, where storms
are of rare occurrence and even strong winds almost unknown. They are
traversed by ocean currents which are strong and constant, flowing towards
the north-west from the coast of Peru; {278} and these physical conditions
have had a powerful influence on the animal and vegetable forms by which
the islands are now inhabited. The Galapagos have also, during three
centuries, been frequently visited by Europeans, and were long a favourite
resort of buccaneers and traders, who found an ample supply of food in the
large tortoises which abound there; and to these visits we may perhaps
trace the introduction of some animals whose presence it is otherwise
difficult to account for. The vegetation is generally scanty, but still
amply sufficient for the support of a considerable amount of animal life,
as shown by the cattle, horses, asses, goats, pigs, dogs, and cats, which
now run wild in some of the islands.

[Illustration: MAP OF THE GALAPAGOS.]

The light tint shows a depth of less than 1,000 fathoms.
The figures show the depth in fathoms.

_Absence of Indigenous Mammalia and Amphibia._--As in all other oceanic
islands, we find here no truly indigenous mammalia, for though there is a
mouse of the American genus Hesperomys, which differs somewhat from any
known species, we can hardly consider this to be indigenous; first, because
these creatures have been little studied in South America, and there may
yet be many undescribed species, and in the second place because even had
it been introduced by some Europ