CHAP. XVII.] 
MAMMALIA. 
235 
Sciurus (100 — 120 sp., including the sub-genera Spermosciurus, 
Xerus, Macroxus, Eheithrosciurus, and Khinosciurus), 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, Palaearctic 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 Einland to North China and Japan, 
and southward through India and Ceylon, to Malacca and Java, 
with a species in Eormosa ; 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 (5 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. Spermophilus (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 Russia to the Amoor and Kams- 
chatka, most abundant in the desert plains of Tartary and Mon- 
golia. Arctomys (8 sp.), the marmots, are found in the northern 
parts of North America as far down as Virginia and Nebraska 
to the Rocky 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 Rocky Mountains from the Upper Missouri to the 
Red River and Rio Grande (Plate XIX., vol. ii. p. 129). Anoma- 
lous ( 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. 
