PYGATHRIX 53 
DUSKY LANGUR. 
Type locahty. Unknown. 
Geogr. Distr. Tenasserim, Mt. Muleyit, 5,000 feet elevation; 
Siam. 
Color. Fore part and sides of head black, the hairs on forehead 
rather stiff, those in center standing erect, those on side shooting away 
at right angles to head; hairs on side of head very long extending far 
behind ears; crown of head brownish black; occipital crest brownish 
white; dorsal line Prout’s brown, sometimes mummy brown, always 
lighter than rest of upper parts which are sooty black, this color also 
extending over the flanks ; arms above elbows paler, sometimes yellow- 
ish brown, sometimes with a reddish shade; forearms and hands black 
or brownish black; space around eyes yellow in skin, probably flesh 
color in life, rest of face black; some white hairs on upper lip and 
on chin; throat sparsely covered with blackish hairs, as is also the 
under side of the arms; a black bar across chest at shoulders; rest of 
under parts grayish brown; outer edge of thigh to knee black; outer 
side grayish brown; inner side slightly paler; hands and feet black; tail 
at base above like back, rest dark olive gray, peneath paler. 
Measurements. Total length, 1,120; tail, 570; foot, 145, (skin). 
Skull : total length, 96.6 ; occipito-nasal length, 80; intertemporal width, 
42.8; width of braincase, 55.3; Hensel, 68; zygomatic width, 73.5; 
median length of nasals, 11.2; length of upper molar series, 27.9; 
length of upper canines, 17.9; length of mandible, 72.3; length of 
lower molar series, 33.9. 
This is a well marked species of the Malay Peninsula, easily 
recognizable by the light nuchal crest, and the paler dorsal line amid 
the general sooty black upper parts. There is a certain amount of 
variation among individuals some being lighter than others, but they 
all adhere to the same pattern, and are easily recognizable. The newly 
born young, according to Anderson, are bright fulvous, but this color 
soon changes and becomes ashy brown. This rufous color lingers 
longest on the head, throat, flanks, thighs and apical half of the tail. 
Reid’s mention of this species (1. c.) contains no description of the 
animal, and the name opscurus could not be accepted had it not been 
adopted by subsequent authors who gave full descriptions, in some 
cases taken from Reid’s own example, and these were published prior 
to the bestowal of any other name upon the species. The type of 
Semnopithecus albo-cinereus Eydoux et Souleyet, is in the Paris 
Museum, and, as their plate shows, is the same as S. opscurus Reid. 
