[T2 CLYED AND) MUSK CHAP, 
their darker coat in the spring. This is, however, only an 
extreme case of a change which is general. Most animals get 
a thicker fur in winter and exchange it for a lighter one in 
summer. And the hues of the coat change in correspondence. 
Glands of the Skin.— The great variety of integumental 
glands possessed by the Mammalha distinguishes them from any 
group of lower Vertebrates. This variability, however, only con- 
cerns the anatomical structure of the glands in question. Histo- 
logically they are all of them apparently to be referred to one of 
two types, the sudoriparous or sweat gland and the sebaceous 
gland. Simple sweat and sebaceous glands are abundant in 
mamunals, with but a few exceptions. The structures that we are 
now concerned with are agglomerations of these glands. The 
mamiary glands will be treated of in connexion with the mar- 
supium; they are either masses of sweat glands, or of sebaceous 
glands whose secretion has been converted into milk. 
Many Carnivora possess glands opening to the exterior, near 
the anus, by a large orifice. These secrete various odoriferous 
substances, of which the well-known “civet” is an example. 
Other odoriferous glands are the musk glands of the Musk-deer 
and of the Beaver; the suborbital gland of many Antelopes; the 
dorsal gland of the Peccary, which has given the name of 
Dicotyles to the genus on account of its resemblance in form to 
a navel. This gland may be seen to secrete a clear watery fluid. 
The Elephant has a gland situated on the temple, which is said 
fo secrete during certain periods only, and to be a warning to 
leave the animal alone. Very remarkable are the foot glands of 
certain species of Rhinoceros ; they are not universally present 
in those animals, and are therefore useful as specific distinctions. 
On the back of the root of the tail in many Dogs are similar 
glands. The Gentle Lemur (Hapalemur) has a peculiar gland 
upon the arm, about the size of an almond, which in the male 
underlies a patch of spiny outgrowths. In Lemur varius is a 
hard patch of black skin which may be the remnants of such 
a gland. It is thought that the callosities on the legs of Horses 
-and Asses are remnants of glands. 
One of the most complex of these structures which has been 
examined microscopically exists in the Marsupial J/yrmecobius.' 
On the skin of the anterior part of the chest, just in front of the 
! Proc. Zool. Soc. 1887, p. 527. 
