or U/igka Ape of Sumatra. 135 



its use is not well known, but it is not improbable that it is an 

 appendage to the organ of voice. Sometimes, when irritated, 

 I have observed him inflate the pouch, uttering at the same 

 time a hollow barking noise * ; for the production of which, 

 the rushing of the air into the sac was an adjuvant. The in- 

 flation of the pouch was not, however, confined to anger ; for, 

 when pleased, he would purse the mouth, drive the air with 

 an audible noise into the sac ; or when yawning, it was also 

 inflated ; and in all instances he would gradually empty the 

 sac, as if he derived a pleasure from it. When the sac has 

 been distended, I have often pressed on it, and forced the 

 air contained within it into the mouth, the animal not evincing 

 at the time any sign of its being an annoyance to him. When 

 uttering the barking noise, the pouch is not inflated to the same 

 extent as when he yawns. It has been stated in an American 

 publication, that the use of the air-sac is for a swimming- 

 bladder. It may be said in refutation (if the assertion is not 

 too absurd to be refuted) that the animal being one day washed 

 in a large tub of water, although much frightened, did not 

 inflate or make the least attempt to inflate the sac. He is 

 destitute of cheek-pouches as a reservoir for food. 



When sleeping, he lies along either on the side or back, 

 resting the head on the hands, and seemed always desirous of 

 retiring to rest at sunset; but would often (I suppose from 

 his approximation to civilisation) indulge in bed some time 

 after sunrise ; and frequently when I awoke I have seen him 

 lying on his back, his long arms stretched out, and, with eyes 

 open, appearing as if buried in deep reflection. The sounds 

 he uttered were various : when pleased at a recognition of his 

 friends, he would utter a peculiar squeaking chirping note ; 

 when irritated, a hollow barking noise was produced ; but 

 when angry and frightened, or when chastised, the loud gut- 

 tural sounds of ra, ra, ra, invariably followed. When I ap- 

 proached him for the first time in the morning, he greeted me 

 with his chirping notes, advancing his face at the same time, 

 as if intended for the purpose of salutation. He had a gravity 

 of look and mildness of manner, and was deficient in those 

 mischievous tricks so peculiar to the monkey tribe. In only 

 one instance did I experience any mischief from him, and that 

 was in his meddling with my inkstand : he had a penchant for 

 the black fluid, would drink the ink, and suck the pens, when- 

 ever an opportunity offered of his gratifying this morbid pro- 

 pensity. He soon knew the name of Ungka, which had been 



* When the barking noise was made, the lips were pursed out, and the 

 air driven into the sac, at the same time that the sound was uttered, the 

 lower jaw was also a little protruded. 



K 4 



