great a change in latitude. Hence, although the vegetation of this northern
district presents a marked difference when compared with that of the southern ;
yet the zoology in many respects has, like the general aspect of the landscape, a
very uniform character. The specimens were chiefly collected from the P e n i n su
l a OF T r e s M o n t e s , the C h o n o s A r c h ip e l a g o (from latitude 4 6 ° to 4 3° 3 0'),
C h i l o e with the adjoining islets, and V a l d iv ia . The contrast between the
physical conditions and productions of the East and West coasts of this part of
South America is very remarkable. On one side of the Cordillera, great heavy
clouds are driven along by the western gales in unbroken sheets, and the indented
land is clothed with thick forests; whilst on the other side of this great range, a
bright sky, with a clear and dry atmosphere, extends over wide and desolate
plains.
C h i l e in the neighbourhood of C o n c e p c io n (latitude 3 6° 4 2 ' S-) may be called
a fertile land; for it is diversified with fine woods, pasturage, and cultivated
fields. But towards the more central districts (near V a l p a r a is o and S a n t ia g o )
although by the aid of irrigation, the soil in the valleys yields a most abundant
return, yet the appearance of the hills, thinly scattered with various kinds of
bushes and cylindrical Opuntias, bespeaks an arid climate. In winter, rain is
copious, but during a long summer of from six to eight months, a shower never
moistens the parched soil. The country has a very alpine character, and is
traversed by several chains of mountains extending parallel to the Andes. These
ranges include between them level basins, which appear once to have formed the
beds of ancient channels and bays, such as those now intersecting the land
further to the south. North of the neighbourhood of Valparaiso, the climate
rapidly becomes more and more arid, and the land in proportion desert. Beyond
the valley of C o q u im b o (latitude 3 0 °.) it is scarcely habitable, excepting in the
valleys of Gnasco, Copiapo, and Paposa, which owe their entire fertility to the
system of irrigation, invented by the aboriginal Indians and followed by the
Spanish colonists. Northward of these places, the absolute desert of Atacama
forms a complete barrier, and eastward, the snow-clad chain of the Cordillera
separates the Zoological province of Chile, from that of the wide plains which
extend on the other side of the Andes.
The last district which it is at all necessary for me to mention here, is that
of the G a l a p a g o s A r c h i p e l a g o , situated under the Equator, and between five
and six hundred miles West of the coast of America. These islands are entirely
volcanic in their composition ; and on two of them the volcanic forces have within
late years been seen in activity. There are five principal islands, and several
smaller ones : they cover a space of 2° 10' in latitude, and 2° 35' in longitude. The
climate, for an equatorial region, is far from being excessively hot: it is extremely
dry; and although the sky is often clouded, rain seldom falls, excepting during
one short season, and then its quantity is variable. Hence, in the lower part
of these islands, - even the more ancient streams of lava (the recent ones
still remaining naked and glossy) are clothed only with thin and nearly leafless
bushes. At an elevation of 1200 feet, and upwards, the land receives the moisture
condensed from the clouds, which are drifted by the trade wind over this part
of the ocean at an inconsiderable height. In consequence of this, the upper
and central part of each island supports a green and thriving vegetation; but
from some cause, not very easily explained, it is much less frequented, than
the lower and rocky districts are, by the feathered inhabitants of this archipelago.
By a reference to the localities here described, it is hoped that the reader
will obtain some general idea of the nature of the different countries inhabited
by the several animals, which will be described in the following sheets.
The vertebrate animals in my collection have been presented to the following
museums: — the Mammalia and Birds to the Zoological Society; the Fishes to
the Cambridge Philosophical Society; and the Reptiles, wEen described, will be
deposited in the British Museum. For the care and preservation of all these and
other specimens, during the long interval of time between their arrival in this
country and my return, I am deeply indebted to the kindness of the Rev. Professor
Henslow of Cambridge. With respect to the gentlemen, who have undertaken
the several departments of this publication, I hope they will permit me
here to express the great personal obligation which I feel towards them, and
likewise my admiration at the disinterested zeal which has induced them thus to
bestow' their time and talents for the good of Science.