Chap. III. MOEAL SENSE. 75 



animals perform many little services for each other: 

 horses nibble, and cows lick each other, on any spot 

 which itches : monkeys search for each other's external 

 parasites ; and Brehm states that after a troop of the 

 Cercopithecus griseo-viridis has rushed through a thorny 

 brake, each monkey stretches itself on a branch, and 

 another monkey sitting by " conscientiously " examines 

 its fur and extracts every thorn or burr. 



Animals also render more important services to each 

 other : thus wolves and some other beasts of prey hunt 

 in packs, and aid each other in attacking their victims. 

 Pelicans fish in concert. The Hamadryas baboons turn 

 over stones to find insects, &c. ; and when they come to 

 a large one, as many as can stand round, turn it over 

 together and share the booty. Social animals mutually 

 defend each other. The males of some ruminants come 

 to the front when there is danger and defend the herd 

 with their horns. I shall also in a future chapter give 

 cases of two young wild bulls attacking an old one in 

 concert, and of two stallions together trying to drive 

 away a third stallion from a troop of mares. Brehm 

 encountered in Abyssinia a great troop of baboons which 

 were crossing a valley : some had already ascended the 

 opposite mountain, and some were still in the valley : 

 the latter were attacked by the dogs, but the old males 

 immediately hurried down from the rocks, and with 

 mouths widely opened roared so fearfully, that the dogs 

 precipitately retreated. They were again encouraged 

 to the attack ; but by this time all the baboons had re- 

 ascended the heights, excepting a young one, about six 



monkeys extracting thorns from each other, see s. 54. With respect to 

 the Hamadryas turning over stones, the fact is given (s. 76) on the 

 evidence of Alvarez, whose observations Brehm thinks quite trust- 

 worthy. For the cases of the old male baboons attacking the dogs, see 

 s. 79 ; and with respect to the eagle, s. 56. 



