132 SPECIAL EXPRESSIONS: Chap. V. 



Young Orangs, when tickled, likewise grin and make 

 a chuckling sound; and Mr. Martin says that their eyes 

 grow brighter. As soon as their laughter ceases, an ex- 

 pression may be detected passing over their faces, which, 

 as Mr. Wallace remarked to me, may be called a smile. 

 I have also noticed something of the same kind with 

 the chimpanzee. Dr. Duchenne — and I cannot quote a 

 better authority — informs me that he kept a very tame 

 monkey in his house for a year; and when he gave it dur- 

 ing meal-times some choice delicacy, he observed that 

 the corners of its mouth were slightly raised; thus an 

 expression of satisfaction, partaking of the nature of an 

 incipient smile, and resembling that often seen on the 

 face of man, could be plainly perceived in this animal. 



The Cebus azarce, 11 when rejoiced at again seeing a 

 beloved person, utters a peculiar tittering (kicliernclen) 

 sound. It also expresses agreeable sensations, by drawing 

 back the corners of its mouth, without producing any 

 sound. Eengger calls this movement laughter, but it 

 would be more appropriately called a smile. The form 

 of the mouth is different when either pain or terror is 

 expressed, and high shrieks are uttered. Another spe- 

 cies of Cebus in the Zoological Gardens (C. liypoleacus) 

 when pleased, makes a reiterated shrill note, and likewise 

 draws back the corners of its mouth, apparently through 

 the contraction of the same muscles as with us. So does 

 the Barbary ape (Inuus ecaudatus) to an extraordinary 

 degree; and I observed in this monkey that the skin of 

 the lower eyelids then became much wrinkled. At the 

 same time it rapidly moved its lower jaw or lips in a 

 spasmodic manner, the teeth being exposed; but the 

 noise produced was hardly more distinct than that which 



11 



Rengger (' Saugetheire von Paraquay', 1830, s. 46) 

 kept these monkeys in confinement for seven years in 

 their native country of Paraguay. 



