Chap. V. MONKEYS. 133 



we sometimes call silent laughter. Two of the keepers 

 affirmed that this slight sound was the animal's laughter, 

 and when I expressed some doubt on this head (being at 

 the time quite inexperienced), they made it attack or 

 rather threaten a hated Entellus monkey, living in the 

 same compartment. Instantly the whole expression of 

 the face of the Inuus changed; the mouth was opened 

 much more widely, the canine teeth were more fully 

 exposed, and a hoarse barking noise was uttered. 



The Anubis baboon (Cynocephalus anubis) was first 

 insulted and put into a furious rage, as was easily done, 

 by his keeper, who then made friends with him and 

 shook hands. As the reconciliation was effected the ba- 

 boon rapidly moved up and down his jaws and lips, and 

 looked pleased. When we laugh heartily, a similar move- 

 ment, or quiver, may be observed more or less distinctly 

 in our jaws; but with man the muscles of the chest are 

 more particularly acted on, whilst with this baboon, and 

 with some other monkeys, it is the muscles of the jaws 

 and lips which are spasmodically affected. 



I have already had occasion to remark on the curious 

 manner in which two or three species of Macacus and 

 the Cynopithecus niger draw back their ears and utter a 

 slight jabbering noise, when they are pleased by being 

 caressed. With the Cynopithecus (fig. 17), the corners 

 of the mouth are at the same time drawn backwards 

 and upwards, so that the teeth are exposed. Hence this 

 expression would never be recognized by a stranger as 

 one of pleasure. The crest of long hairs on the forehead 

 is depressed, and apparently the whole skin of the head 

 drawn backwards. The evebrows are thus raised a little, 

 and the eyes assume a staring appearance. The lower 

 evelids also become slightlv wrinkled; but this wrin- 

 kling is not conspicuous, owing to the permanent trans- 

 verse furrows on the face. 



