SKIN AND MUSCLES. 699 
by the habitual winking of the upper eyelid. The nostrils 
are two slits at the end of the snout, and are connected 
with the mouth by a “hare-lip” cleft in the middle of the 
upper lip. In front of the mouth are seen the chisel-edged 
incisors, a pajr on the mandibles, and two pairs on the pre- 
maxille—the smaller pair hidden behind the larger pair. 
The first milk incisors above and below never cut the gum, 
but are absorbed before birth; the second milk incisors 
above (there are none below) are functional, but are shed 
about the third week of extra-uterine life; the same is true 
of the milk premolars. Into the toothless gap or diastema 
between the front and back teeth the hairy skin of the lips 
projects into the mouth. This generally occurs in Rodents, 
and is said to prevent the inedible substances which they 
gnaw from passing backwards to the gullet. On the sides 
’ of the snout, and about the eyes, there are tactile hairs or 
vibrissze. 
The plump trunk is separated from the head by a short 
neck. ‘The tail is very short, but in the scampering wild 
rabbit it is conspicuous as a white tuft, which some 
naturalists interpret as a directive signal. Beneath the base 
of the tail the food canal ends, and beside the anus are the 
openings of the perineal glands, whose secretion has a char- 
acteristic odour. In front of the anus is the urogenital 
aperture,—in the male at the end of an ensheathed penis, 
in the female a slit or vulva, with an anterior process or 
clitoris—the homologue of the penis. Beside the penis in 
the male lie the scrotal sacs, into which the testes descend 
when the rabbit becomes sexually mature. Along the 
ventral surface of the thorax and abdomen in the female 
there are four or five pairs of small teats or mamme. 
The limbs have clawed digits, five on the fore-feet, four 
on the hind-feet ; they are very hairy. 
Skin and muscles.—The skin is thickly covered with 
hair, and has the usual sebaceous and sudorific glands, 
besides special glands, such as the perineal glands beside 
the anus, the glands of the eyelids, the lachrymal glands, 
and the mammary glands developed in the females. 
Between the skin and the subjacent muscles there is a 
layer of fatty tissue, known as the panniculus adiposus ; it 
is usually present in Mammals, but absent in the common 
