THE MAN-LIKE APES. 39 



" the voice is grave and penetrating, resembling the 

 sounds goek, goek, goek, goek, goek ha ha ha ha haauaa, 

 and may be easily heard at a distance of half a league." 

 While the cry is being uttered, the great membranous bag 

 under the throat which communicates with the organ of 

 voice, the so-called " laryngeal sac," becomes greatly dis- 

 tended, diminishing again when the creature relapses into 

 silence. 



M. Duvaucel, likewise, affirms that the cry of the Sia- 

 mang may be heard for miles making the woods ring 

 again. So Mr. Martin* describes the cry of the agile 

 Gibbon as " over-powering and deafening " in a room, 

 and " from its strength, well calculated for resounding 

 through the vast forests." Mr. Waterhouse, an accom- 

 plished musician as well as zoologist, says, " The Gibbon's 

 voice is certainly much more powerful than that of any 

 singer I ever heard." And yet it is to be recollected that 

 this animal is not half the height of, and far less bulky in 

 proportion than, a man. 



There is good testimony that various species of Gibbon 

 readily take to the erect posture. Mr. George Bennett,f 

 a very excellent observer, in describing the habits of a 

 male Hylobates syndactylus which remained for some 

 time in his possession, says : " He invariably walks in the 

 erect posture when on a level surface ; and then the arms 

 either hang down, enabling him to assist himself with his 

 knuckles ; or what is more usual, he keeps his arms up- 

 lifted in nearly an erect position, with the hands pendent 

 ready to seize a rope, and climb up on the approach of 

 danger or on the obtrusion of strangers. He walks rather 

 quick in the erect posture, but with a waddling gait, and 

 is soon run down if, whilst pursued, he has no opportunity 



* " Man and Monkies," p. 423. 



f "Wanderings in New South Wales, Vol. II. chap. viii. 1834. 



