Plate 3. 



I'roii! it)- 



THE ]3AR0METER OF MALENESS— AMONG THJ' Al'KS. 



All tlie Man-like Apes possess great canine teeth and powerful voices. In the Orang- 

 utan the compass of the voice is enormously heightened by means of a huge wind-bag 

 which encircles the neck. The wind-bag is seen in fig. i, which also shows the great 

 folds of skin developed by adult males on each side of the face. In other species, as in 

 the Tamarin Marmoset {Midas imperator) (fig. 2), and the Satan monkey (Pithecia 

 satanus) (fig. 3), "ornaments" in the shape of beards and moustaches are developed, 

 while in the Mandrill (fig. 4) the face is vividly coloured, 



[Face page 44. 



