272 ALLEN'S NATURALIST'S LIBRARY. 



coloured. . . . With respect to the origin of the habit, it 

 seems to me probable that the bright colours, whether 

 on the face or hinder end, or as in the Mandrill, on both, 

 serve as a sexual ornament and attraction. . . . The 

 fact that it is only the Monkeys (with those parts brightly 

 coloured), which as far as at present known, act in this manner 

 as a greeting towards other Monkeys, renders it doubtful 

 whether the habit was first acquired from some independent 

 cause, and that afterwards the parts in question were coloured 

 as a sexual ornament ; or whether the colouring and the habit 

 of turning round were first acquired through variation and 

 sexual selection, and that afterwards the habit was retained as 

 a sign of pleasure, or as a greeting, through the principle of 

 inherited association." 



X. THE ARABIAN BABOON. PAPIO HAMADRYAS. 



Sinria hamadryas, Linn., Syst. Nat., i., p. 36 (1766). 



Le tartarin, F. Cuvier and Geoffr., Mamm., vol. i., livr. 5 



(1819). 

 Cynocephalus hamadryas, Fr. Cuvier, Hist. Nat. Mammif., p. 



129, pi. 46 (<?). 

 Papio hamadryas, Geoffr., Ann. Mus., xix., p. 103 (1812); 



Schl., Mus. Pays Bas, vii., p. 129 (1876, in part). 

 Hamadryas agyptiaca, Gray, Cat. Monkeys Brit. Mus., p. 34 



(1870). 



Characters. Male. Size of a large Pointer Dog ; muzzle long ; 

 nose slightly longer than the upper lip ; nostrils terminal, 

 separated by a furrow above and in front; face naked, the 

 ridges parallel to the nose, and far less prominent than 

 in the Mandrill or Drill ; eyes deep-set ; brows overhanging ; 

 ears naked ; a large mane, mantle-like, on the throat, neck, 



