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RODENTS. 
a distinct genus, but likewise a separate subfamily, although they were till recently 
included among the true squirrels. Their skulls are remarkable for the elongated 
form of the region of the face, while the forehead is much broader than in any 
other type; and the process defining the hinder border of the socket of the eye is 
so elongated as to cause the eye to be almost surrounded by bone. In the upper 
jaw there may be either one or two pairs of small premolar teeth; and the molars 
are much more complex than in any other squirrels, closely approaching those 
of the dormice in structure; the upper molars having only three transverse 
plates, instead of the four characterising those of the other members of the 
family. 
One of the prettiest representatives of the group is Whitehead’s pigmy squirrel 
(N. whiteheadi), from North Borneo, in which the head and body measure only 
about d j- inches in length, and the ears are surmounted by extraordinarily long 
tufts of black and white hairs, apparently more elongated than in any other squirrel. 
This little animal, which is grizzled olive grey in general colour, may be commonly 
seen running up and down the trunks of the forest trees on Mount Kina Balu. 
The Sewellels. 
Family HAFLODONTIDN. 
These North American Rodents differ so remarkably from the other living forms 
that they are regarded as constituting a family by themselves, of which the nearest 
affinities are supposed to be with the Squirrel family. They differ from all the 
members of that family by their extremely flattened and broad skulls, in which 
there is no postorbital process defining the hinder part of the upper border of the 
socket of the eye. The molar teeth have no roots, and the first pair of premolars 
in the upper jaw are exceedingly minute. 
Common The common sewellel (Haplodon rufus ) is an animal measuring 
SeweUei. about a foot in length, exclusive of the stump-like tail, which measures 
little more than an inch. The general colour of the fur is brown, more or less 
mingled with black, with the under-parts greyish; the front teeth being yellow. 
The general form of the animal is short and clumsy, with the body relatively large 
and cylindrical. Dr. Hart Merriam observes that “ this singular animal, which has 
come down to us as a relic of the past, and has no near affinities with any existing 
group, inhabits a narrow strip of country on the north-west coast of the United 
States. All the specimens thus far obtained have come either from Oregon or 
Washington, or from the Chilukweyuk River near its junction with the Fraser, 
just across our border in British Columbia.” The animal lives in companies, 
constructing burrows in moist ground. 
Californian The Californian sewellel (H. major ) — the mountain-beaver of 
Sewellel. the inhabitants—is a larger animal, measuring 16 inches in length, 
with greyish brown fur above. These Rodents inhabit the Sierra Nevada, and are 
largely aquatic in their habits. Mr. C. A. Allen, by whom the species was 
discovered, writes that they “ live in small colonies, and inhabit wet ground where 
there is plenty of running water. They are very compact and strong, with a head 
