58 
UPPER MAMMAL GALLERY. 
[Case 12.' 
1 Case 
VL] 
[ Cases 
ii; 11 A 
IIB.] 
what is called a town. Frequently they have to share their 
home with weasels, burrowing-owls, and rattlesnakes. 
1 The Squirrels (Sciu7ms, kc.) form the largest group of the 
present family, distributed over the whole world, with the 
exception of the Australian region. They range in size from 
species more than a foot in length, such as the Purple Giant 
Squirrel, Ratufa indica ( 682 ), of India, down to others scarcely 
larger than Mice, as, for example, the Black-eared Squirrel, 
yannosciimis melanotis, and the Pigmy Squirrel, Ax exilis ( 671 ), 
of Borneo. Squirrels are generally bright-coloured, and vary in 
an extraordinary degree, as may be gathered from an exairdnation 
of the instructive series of Scimnfs liyi^opyrrhus (691 to 715 ), the 
Grizzled Squirrel. This species is ornamented with patches 
or bands of white, yellow, grey, brown, and black, in every 
combination, each variety passing, by insensible gradations, 
into the next. Specimens of the Common Squirrel, S. vulgaris 
( 678 ), exhibit some of the local and seasonal variations 
observable in this species ; and attention may be directed to the 
tine series of foreign Squirrels in the case. The beautiful 
Groove-toothed Squirrel of Borneo is made the type of the 
distinct genus Rkitliroscmrus ( 669 ) on account of its grooved 
upper incisors. 
The Beavers, Castoindce (case VI), are distinguished by the 
Hat and scaly tail, webbed hind-feet, and soft thick fur. The 
incisor teeth are of remarkable strength and sharpness, and 
with them their owners are able to gnaw through the trunks of 
largo trees, which they require tor the construction of dams, 
in a short space of time. These interesting animals are rapidly 
becoming exterminated, owing to the great demand for their 
fur, so that whereas they formerly inhabited the whole of 
Northern Europe, Asia, and America, they are now to be found 
only in a few isolated localities in the most inaccessible parts 
of their proper range. Many naturalists regard the American 
Beaver as specifically distinct from the European, Castor fiber 
( 756 ), and name it Castor canadensis ( 757 ) ; a group of the 
latter is shown in one of the bays. 
The Myomorpha, or Rat section (cases 11, 11 A, and 11 B), 
’ contains numerous genera and a vast number of species, spread 
