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36 ZOOLOGICAL GEOGRAPHY. [part hi.
It is doubtful whether mammals or batrachians have any means
of passing, independently of man's assistance ;
the former having
but one doubtfully indigenous representative, the latter none at
all. The remarkable absence of all gay or conspicuous flowers
in these tropical islands, though possessing a zone of fairly
luxuriant shrubby vegetation, and the dependence of this phenomenon
on the extreme scarcity of insects, has been already
noticed at Vol. I. p. 461, when treating of a somewhat similar
peculiarity of the New Zealand fauna and flora.
I. South Temperate America, or the Chilian Sub-region.
This sub-region may be generally defined as the temperate
portion of South America. On the south, it commences with the
cold damp forests of Tierra del Fuego, and their continuation up
the west coast to Chiloe and northward to near Santiago. To the
east we have the barren plains of Patagonia, gradually changing
towards the north into the more fertile, but still treeless, pampas
of La Plata. Whether this sub-region should be continued across
the Eio de la Plata into Uruguay and Entre-rios, is somewhat
doubtful. To the west of the Parana it extends northward over
the Chaco desert, tiU we approach the border of the great forests
near St. Cruz de la Sierra. On the plateau of the Andes, however,
it must be continued still further north, along the " paramos "
or alpine pastures, till we reach 5° of South latitude. Beyond this
the Andes are very narrow, having no double range with an inter-
vening plateau; and although some of the peculiar forms of the tem-
perate zone pass on to the equator or even beyond it, these are not
sufficiently numerous to warrant our 'extending the sub-region to
include them. Along with the high Andes it seems necessary to in-
clude the western strip of arid country, which is mostly peopled
by forms derived from Chili and the south temperate regions.
Mammalia.—This sub-region is well characterised by the pos-
session of an entire family of mammalia having Neotropical
afi&nities—the Chinchillidge. It consists of 3 genera Chinchilla
(2 sp.), inhabiting the Andes of Chili and Peru as far as 9° south
latitude, and at from 8,000 to 12,000 feet altitude ; Lagidium
(3 sp.), ranging over the Andes of Chili, Peru, and South Ecuador,