126 Mammals of Eastern Asia 
The Dusky or Spectacled Leaf Monkeys, Trachypithecus 
obscurus of the Malay Peninsula (up to 5000 feet), resemble 
T. phayrei by having circles of unpigmented skin around the 
eyelids and mouth. The color is dark gray. One race, T. o. 
flavicauda, found in peninsular Siam, has the tail washed with 
yellow. Other scarcely distinguishable races have been named. 
A race, T. o. germaini of Siam, Annam, Cambodia, and Cochin- 
China, sometimes treated as a race of the Javan T. pyrrhas, has 
yellowish or silvery hairs on the temples, cheeks, and ears. The 
tail and forearms are dark. A still paler race is argentens, the 
Silvery Langur of Laos, Annam, and Cochin-China. Trachy- 
pithecus o. cristatus from the Malay Peninsula likewise has 
been treated as a race of T. pyrrhus. It is dark gray, with the 
tips of the hairs touched with silvery gray. The limbs, back, and 
tail are darker. There is a crest. 
The length of head and body in T. o. germaini varies from 
19% to 23% inches; in T. o. cristatus (Selangor) it is about 
22 inches; in T. o. obscurus, from 18 to 27 inches; the length 
of the tail, respectively, is from 28% to 33 inches, about 27 
inches, and from 28 to 32 inches. 
The Tonkin Langur or Leaf Monkey, Trachypithecus 
francoisi, is .a blackish form with a white stripe running from 
the corner of the mouth to the ear. The hairs of the crest rise 
from two whorls. In T. laotum of Laos the white area includes 
the forehead, cheeks, and sides of the neck. In T. poliocephalus 
from northeast Tonkin the head and neck are buffy white. In 
T. delacouri of Annam the outer sides of the thighs are pure 
white. 
The forms francoisi and delacouri have the length of head 
and body respectively about 25 and 23 inches, and the length of 
the tail 33 to 34 inches. The dimensions recorded for laotum 
and poliocephalus may be erroneous and are not here repeated. 
Trachypithecus f. delacouri is a strikingly colored Langur with 
a broad white area across the lower back and rump, a white 
