PDF - Wallace Online

CHAP. XVII.] MAMMALIA. 235
Sciurus (100—120 sp., including the sub-genera Spermosciurus,
Xerus, Macroxus, Eheithrosciurus, and Ehinosciurus), comprises
the true squirrels, and occupies the area of the whole family
wherever woods and forests occur. The approximate number of
species in each region is as follows : Nearctic 18, Paleearctic 6,
Ethiopian 18, Oriental 50, Australian (Celebes) 5, Neotropical 30.
Sciuropterus (16—19 sp.), comprises the flat-tailed flying squirrels,
which range from Lapland and Finland to North China and Japan,
and southward through India and Ceylon, to Malacca and Java,
with a species in Formosa ;
while in North America they occur
from Labrador to British Columbia, and south to Minnesota and
Southern California. Pteromys (12 sp.), comprising the round-
tailed flying squirrels, is a more southern form, being confined to
the wooded regions of India from the Western Himalayas to Java
and Borneo, with species in Formosa and Japan. Tamias{b sp.),
the ground squirrels, are chiefly North American, ranging from
Mexico to Puget's Sound on the west coast, and from Virginia to
Montreal on the Atlantic coast; while one species is found over all
northern Asia. Spermo'philus (26 sp.), the pouched marmots, are
confined to the Nearctic and Palsearctic regions ; in the former ex-
tending from the Arctic Ocean to Mexico and the west coast, but
not passing east of Lake Michigan and the lower Mississippi; in the
latter from Silesia through South Eussia to the Amoor and Kamschatka,
most abundant in the desert plains of Tartary and Mon-
golia. Ardomys (8 sp.), the marmots, are found in the northern
parts of North America as far down as Virginia and Nebraska
to the Eocky Mountains and British Columbia, but not in Cali-
fornia ; and from the Swiss Alps eastward to Lake Baikal and
Kamschatka, and south as far as the Himalayas, above 8,000 feet
elevation. Cynomys (2 sp.), the prairie-dogs, inhabit the plains
east of the Eocky Mountains from the Upper Missouri to the
Eed Eiver and Eio Grande (Plate XIX., vol. ii. p. 129). Anoma-
lurus (5 sp.), consists of animals which resemble flying-squirrels,
but differ from all other members of the family in some points of
internal structure. They form a very aberrant portion of the
Sciuridse, and, according to some naturalists, a distinct family.
They inhabit West Africa and the island of Fernando Po.