TO MAMMALS. XI 



In the majority of Mammals there is little to mark the signs of 

 sex, except superior size and strength, and a different color in a 

 few J but in certain tribes there are other external marks. The 

 Lion, and a few others have a shaggy mane, and the males of many 

 Ruminants are adorned with fine horns, either altogether absent 

 in the females, or much smaller. In a few, the canine teeth are 

 greatly superior in size in the males, or only found in them. 



The male generative organs differ much in size and shape, and 

 some are provided with the succenturiate glands of large size, 

 whilst others are wholly without them. The males of some ani- 

 mals have a seasonal development, and at such times only have 

 the power-to procreate, whilst others are able at all seasons. Most 

 animals perhaps are monogamous, a few are polygamous. 



The females of most Mammals have certain periods of heat or 

 eestrum coincident with a catamenial discharge, and will in general 

 only receive the males at these times. The uterus is single in most 

 Mammals, but double in a few, as in the Rabbit, and they open 

 by separate orifices into the vagina. In many of the lower animals, 

 and especially in such as are remarkable for their fecundity, the 

 horns of the uterus are more developed in pregnancy than the body 

 of the uterus, and the foetus lie there, but as we ascend in the scale 

 the body of the uterus becomes larger. 



The urine is contained in the bladder, which is large, and it is 

 evacuated by a distinct opening in the generative organs, except 

 in the Monotremata, the lowest organized Mammals, where there 

 is only one passage for foeces and urine. The excretory canal in the 

 female is quite separate from the vagina. 



Mammals are silent compared with Birds, and their voice is not 

 generally musical or capable of harmony. It is chiefly employed 

 to call one another, or to express anger, fear or hunger. 



The skin contains numerous glands and follicles, secreting a 

 lubricating fluid, to maintain it in a moist and supple state. 



In many animals there are special glands in various parts of the 

 body. Some of the Carnivorahave special anal glands, which usual- 

 ly secrete a fetid fluid. The Elephant has a temporal gland ; and 

 many Ruminants have both large hollow glands below the eyes,' 



