MAMMALIA. ~ 228 
orbital cavity, and smaller space for containing the brain. The breadth of the frontal bone 
or distance between the orbits is not greater than in the smaller scull of the American hare. 
“The margins of the orbits project considerably, so as to produce a well-marked depression in 
‘the anterior part of the frontal bone, included between them. 
Dental formula, incisors 4, canines 3, grinders =, = 28. 
Incisors white, four-sided. Upper ones with a conspicuous but rather shallow groove near 
‘their inner margins anteriorly, and another groove on their sides. The posterior or supple- 
-mental upper incisors have two grooves on their posterior faces, which give them a prismatical 
form. The cutting edges of the incisors are nearly even. 
The fur is every where entirely white, except on the tips of the ears, sich are brownish- 
black. The back and margins of the ears are covered with a close coat of hair, which is 
white to the roots. The hairs lining the interior of the ear are white and moderately long, 
but they are not so close as to prevent the dark: skin from partially appearing. The hair on 
the tips of the ears is mostly brownish-black to its base, a little of it only, where it adjoins to 
the white fur, shewing a wood-brown colour near its roots, The whiskers in some specimens 
are entirely white, in others partially black. The fur on the back is remarkably close and 
fine, that on the belly is longer and not quite so close, The extremities are covered with a 
smooth coat of hair of a pure white colour to the roots. The brush on the soles has a soiled 
yellowish-white colour. The fore-toes are short, and their claws are of a dark-brownish horn 
colour, and are very long and considerably curved, but their general shape nearly resembles 
that of the claws of the common hare. They are more curved and blunter than the claws 
of the American hare, and project much further beyond the fur. The hind-claws are rather 
broader than the fore-ones, dark at the roots and pale at the tips. The tail is covered with 
pretty long fur, woolly at the roots, and of a pure white colour its whole length. The irides 
are of a honey-yellow colour. The skin of the polar-hare, when in full winter dress, is so 
tender, that it is difficult to take it off without tearing it. 
DIMENSIONS. 
; Inches. Lines. Inches, Lines. 
Length of the head and body ‘ > . 22 6 Fore Extremities. 
55. 4rom the nose to the point of the mid- Dent 7s cae it ofehe ada 
dle claw, when the hind leg is stretched out 30 6 eae a ee Ry oe 
5a ; claw . 5 ° . 3 4 
55 of the head, from the occipital spine ¢ middl aa 1 10 
to the end of the nose, measured over the LES © ea ao Hoe a Ce : 
forehead, and pressing down the fur 25 6 ae, URS EIS REC ‘ Te 8 
55 of the head, measured with a pair of Hind Extremities. 
calliper compasses - . 4 6 5 from the heel to the base of the mid- 
5, of the ears, including the fox, meas dle toe > : 2 4 0 
sured posteriorly * , . 4 6 5, of middle toe and claw . 2 6 
“e the ears, from rictus to apex 3 6 5, from the heel to the end of the middle 
ce 5 black fur at the tip of the ear 0 6 claw . . > . 6 6 
oe 5, tail (vertebre) 1 6 5, Of the scull, from the insertion of the 
os 5 tail, including the fur 3 6 incisors to the occipital crest, measured by 
whiskers 3 ties 5 3 6 callipers ° 5 3 10 
3D 9 
