The siamangs generally assemble in large troops, “conducted, it is said, by a chief, whom the Malays believe to be invulnerable, probably because he is more agile, powerful, and difficult to capture than the rest.” “Thus united,” proceeds M. Duvancelle (in a letter addressed to Cuvier), “the siamangs salute the rising and the setting sun with the most terrific cries” (like sun-worshippers), “which may be heard at the distance of many miles, and which, when near, stun when they do not frighten. This is the morning call of the mountain Malays; but to the inhabitants of the town, who are unaccustomed to it, it is an unsupportable annoyance. By way of compensation, the siamangs keep a profound silence during the day, unless when interrupted in their repose or their sleep. They are slow and heavy in their gait, wanting confidence when they climb and agility when they leap, so that they may be easily caught when they can be surprised. But nature, in depriving them of the means of readily escaping danger, has endowed them with a vigilance which rarely fails them; and if they hear a noise which is unusual to them, even at the distance of a mile, fright seizes them and they immediately take flight. When surprised on the ground, however, they may be captured without resistance, either overwhelmed with fear or conscious of their weakness and the impossibility of escaping. At first, indeed, they endeavour to avoid their pursuers by flight, and it is then that their want of skill in this exercise becomes most apparent.”