632 ANATOMY OF VERTEBRATES. 



CHAPTER XXXVI. 



TECULIAR GLANDS OF MAMMALIA. 



Most species of the Mammalian class have their peculiar odour, 

 whereby, mainly, the individuals of such recognise each other ; 

 and, in the gregarious kinds, a stray one may be guided to the 

 herd by scenting the secretion which has been left upon their 

 track. Such odours are commonly due to follicles or glands 

 opening upon some parts of the skin ; but there are, likewise, 

 glands subserving other uses, peculiar to certain species. 



§ 365. Opening upon the head. — In many Ruminants and some 

 hogs, a depression or inverted fold of skin, near and usually 

 anterior to or below the orbit, is perforated by the ducts of nu- 

 merous more or less developed sebaceous follicles, discharging 

 their secretion into the cavity. As this is often placed so as to 

 receive an overflow of the lacrymal secretion, and as a corre- 

 sponding depression is usually present in the large facial plate of 

 the lacrymal bone, it has been termed by French naturalists 

 i larmier : ' by English writers, the tegumentary sac, with its 

 glands and muscles, is called ( suborbital pit or sinus.' In the 

 Indian Antelope (Antilope cervicapra), it is large and deep : a few 

 short hairs project between the glandular orifices at the bottom 

 of the sac : its circumference is entire and provided with radiating 

 and circular strata of muscular fibres on the surface next the 

 depression of bone in which it lies : by these muscles the tegu- 

 mentary pit can be expanded, contracted, protruded, and partially 

 everted, whereby the glandular surface may be brought into con- 

 tact with and rubbed against foreign bodies : the follicles are mul- 

 tilocular and numerous in this species. The odour of the secretion, 

 inclining to musky, may be recognised by a stray individual of a 

 herd, or by the doe, which might thereby be guided to her mate. 

 The gland seems most nearly to relate to the sexual function : it 

 is usually larger in the male than the female, and its development 

 is checked by castration. It is present, but small, in most goats 



