THE GIBBONS. 1 53 



and chest being black, and the back brown ; or the pervading 

 colour may be brown, the sides of the face and the under 

 surface black, and the whiskers white. The index and middle 

 fingers are occasionally webbed together. 



All the hairs on the arm and fore-arm converge towards 

 the wrist. 



Distribution. — This species is confined to Sumatra and to 

 Siam. In the former country it is known by the name of 

 "Ongka" by the Malays, who, with the keen powers of 

 observation they possess in regard to all natural objects, re- 

 cognise two varieties, the white or yellow variety — " Ongka 

 putih," and the black one — "Ongka itam" (ZT. rafflesi). The 

 capped variety {H. pileatus) with its variously coloured forms 

 inhabits Siam. 



Habits.— The habits of the "Ongka" are very similar to 

 those of the Wau-wau, or the Siamang {H. syndadylus). The 

 natives, however, aver that it is much more silent, rarely howl- 

 ing as either of these other two species do. They are also seen 

 generally in quite small troops, and often in pairs only. 



"It is almost impossible," writes Mr. Martin of a specimen 

 that lived formerly in the Zoological Gardens, " to convey in 

 words an idea of the quickness and graceful address of her 

 movements: they may, indeed, be termed aerial, as she seems 

 merely to touch, in her progress, the branches among which 

 she exhibits her evolutions. In these feats her hands and 

 arms are the sole organs of locomotion; her body hanging as 

 if suspended by a rope, sustained by one hand (the right, for 

 example), she launches herself by an energetic movement to 

 a distant branch, which she catches with the left hand. But 

 her hold is less than momentary; the impulse for the next 



