MAMMALIA. 169 
the hair is brownish-gray, and at the bottom bluish-black. Black specklings occur on the 
crown of the head, cheeks, and shoulders, but the tips of the hairs covering those parts are 
white. On the top of the head the hair is short, and there is a large proportion of black in 
that part. The eyelids are white, sometimes the brownish tints are very pale, and the animal 
is grizzly on all the upper parts as in the individual described by Mr. Sabine. The throat, 
chin, lower parts of the cheeks, inside of the thighs, and all the under parts are of a soiled 
white without spots. The fur on the belly is rather thin, but of the same length with that 
on the back. 
The hairs on the ¢ail are longer than those on the back, and are barred with black and 
white, which, when the hairs are distichously arranged, produces an indistinct appearance 
of longitudinal stripes. But when the animal is pursued, the tail is cylindrical, the hairs 
standing out in every direction. In this state, which was the only one in which I had an 
opportunity of observing the living animal, the black and white colours of the tail are 
intermixed, and in nearly equal proportions. The white forms the tips of the hairs, and 
when they are spread out, the tail consequently appears to be bordered with white. There 
is no difference of colour between the upper and under surface of the tail, in which respect 
this species of marmot differs from all the others I have seen except the A. Beecheyt and 
A. Douglasii. 'The scrotum is large and prominent in the spring, but not pendulous. The 
feet are formed like those of A. Richardsoni, and are covered with short hairs, black at the 
roots and white at the tips. The thumb has one joint, and is larger than those of the latter 
animal, but has a smaller nail, which is white. The Sciurus Hudsonius has a shorter thumb 
than either of these marmots, but it is armed with a more conspicuous nail. The hind-feet 
when stretched out reach to the middle of the tail. The palms are naked. The hind soles 
are hairy for about two-thirds of their length from the heels, The claws are dark at the base, 
and pale-brown at their points. 
On comparing the skull of this marmot with that of A. Richardsonii, the cavity for con- 
taining the brain appears greater in proportion, and there is a considerably greater breadth 
between the orbits. The margins of the orbits are not elevated as in the latter, but the bone 
lying between them forms a regular arch in a longitudinal direction, though it is flat trans- 
versely. The space between the orbits is not, however, so great as that between the orbits 
of Scturus Hudsonius. The teeth do not differ from those of A. Richardsonii. 
Dimensions 
Of a recent specimen full grown. 
Inches. Lines. Inches. _ Lines. 
Length of body and head, ‘ a 10 6 Length of middle fore-claw_ . ‘ 0 6L 
os head 5 ‘ 2 2 2 » from heel toend of middle hind-claw 2 2 
ee body ° . . » 8 4 e middle hind-claw s - 0 3k 
er tail (vertebre)» . > 5 3 “ height of ear ; Q 0 3h 
3 including fur . 6 3 ; 
