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 (Budalis 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 (Dzcotyles) 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. 
