y help it in climbing trees.
There are several other peculiarities, which I need not dwell on here,
which have justified its separation from the true squirrels. The
flying membrane, which is quite as large as that of the flying
squirrels, extends from the elbow to the heel instead of from the
wrist, and it is held out by a strong cartilaginous spur starting
from the elbow.

Of the Sciuridae we have many examples in India, which will be
noticed further on.

The _Ischyromyidae_ is founded on a single North American fossil
genus (_Ischyromys typus_), which is nearly allied to the Sciuridae,
but also shows some affinity to the beavers.

The _Haplodontidae_ is also an American family, founded on one genus,
but an existing and not a fossil animal. The _Haplodon rufus_ is a
small burrowing rodent, valued by the Indians both for its flesh and
its skin, of which from twenty to thirty are sewn together to form
a robe; the teeth are rootless, simple, and prismatic, the surface
of each being surrounded by a mere border of enamel.

The _Castoridae_ is the beaver family, which is also unknown in India.
Unlike as this animal is externally to the squirrels, its anatomy
warrants its position in the Sciuromorpha, otherwise one would feel
inclined to include it in the next section.

We see that of the five families, of which this section is composed,
only the second has its representatives in India.

SCIURIDAE--THE SQUIRRELS.

This family contains the true squirrels, including the flying ones,
and the marmots. The distinctive characteristics of the former are
as follows: The gnawing teeth are smooth, compressed. The grinding
teeth are 5--5/4--4 or 4--4/4--4; in the former case the first upper
premolar is small, and sometimes deciduous; they are tubercular, at
least in youth, and rooted. Skull with distinct post-orbital
processes; infra-orbital opening small, usually placed in front of
the maxillary zygomatic process; palate broad and flat; twelve or
thirteen pairs of ribs; tail cylindrical and bushy; feet either
pentadactylous or with a tubercle in place of a thumb on the fore-feet.
Mostly quite arboreal.

_GENUS SCIURUS_.

Premolars, 2--2/1--1; molars, 3--3/3--3; gnawing teeth smooth,
orange-coloured, or brown; no cheek pouches; mammae three or four
pairs; first upper premolar soon lost in many cases; limbs free; form
agile; tail long and very bushy.

Jerdon states that "there are three well marked groups in India
dist