SOCIAL BACKBONED ANIMALS 



141 



importance with reference to detecting the approach of carnivores. 

 But it would also seem to play a part in facilitating mutual 

 recognition between individuals of the same kind. At any rate 

 we often find that social forms are provided, in various parts of 

 the body, with peculiar glands, the secretions of which emit 



Fig. 1106. Hartebeest (Bubalis caama) 



characteristic odours, often, to us, of disagreeable kind. The 

 Rabbit (Lepus cuniculus) is a case in point, for its " rabbity smell " 

 is due to the products of a pair of glands (perineal glands) in the 

 hinder part of the body. The little Peccaries (Dicotyles] of South 

 America possess a good-sized gland under the skin of the back, 

 the secretion being here a stinking oily fluid, the emanations from 

 which no doubt assist in keeping the members of a troop together. 



