158 HYLOBATES 



often resemble the females and have a brownish black pelage. The 

 species is subject to great individual variation. 



Measurements. Head and body, 520; foot, 150. Skull: total 

 length, 114; occipito-nasal length, 93.9; intertemporal width, 49; 

 breadth of braincase, 61.5 ; Hensel, 82.2 ; zygomatic width, 72.4; median 

 length of nasals, .95 ; palatal length, 45.7 ; length of upper canines, 21.5-} 

 length of upper molar series, 29.6 ; length of mandible, 78.6 ; length of 

 lower molar series, 35. 



The specimen called H. choromandus by Ogilby (1. c.) from an 

 unnamed locality, is without doubt this species. It was presented to 

 the Zoological Society of London by General Hardwicke many years 

 before it was described, and at the same time a typical H. hoolock 

 from the same locality had also been presented, name of donor not 

 mentioned. It is stated to be "ashy brown" in color, and is no doubt 

 a young male, or a female. The whiskers are stated to be "black." 

 The description is contained in the words quoted, hardly sufficient 

 to determine a specimen, even if of a new species, particularly if no 

 locality for it was given, but as it was accompanied by a veritable H. 

 HOOLOCK, it may without hesitation be referred to it, as no two species 

 of Hylobates are known to inhabit the same locality. 



While the general and t>'pical hue of this species is black, many 

 varieties are found, even almost wholly white, or yellowish white 

 individuals. In general, however, the Hoolocks may be said to be 

 more steadfast to a typical style of coloring than any other member 

 of the Hylobates group so far as the male is concerned, the variation 

 in the color of the pelage being more often observed in the female. 

 They represent the changeable sex. 



The Hoolock is confined in its range to a comparatively limited 

 district bounded by the Brahmaputra and Irawady Rivers ; its aversion 

 to water, for it cannot swim, probably preventing it from making any 

 effort to cross such broad streams. Like all the members of this 

 genus the Hoolock is arboreal, and although it can make a ludicrous 

 progress over the ground balancing its body by awkwardly holding 

 its long arms bent over its head, its life is passed in the trees, under 

 whose branches it swings itself in a trapeze-like performance in so 

 swift a progress that it can only be likened to the passage of a bird 

 through the air. Mr. Candler has given (1. c.) an interesting account 

 of the habits of this ape, short extracts from which are here g^ven. 

 "He swings along to the thinnest part of a bough, or to the slender end 

 of a bamboo, until it bends to his weight, then with a swing and a 



