Descriptions of East Asiatic Mammals 123 
Asiatic genera are rather unspecialized, having long tails and 
unmodified noses; the other four have one or other of those 
organs modified. 
The long-tailed unspecialized Langurs and Leaf Monkeys 
were once known under the collective name Pithecus, which al- 
though no longer permitted 1 still appears sometimes in print. 
It is customary to use the four names, Semno pithecus, the In- 
dian Holy Monkeys and Purple- faced Langurs ; Trachy pithecus, 
the Capped Leaf Monkeys or Langurs; Presbytis, the Mitred 
Leaf Monkeys; and Pygathrix, the Doucs. These four names in 
the opinions of some authorities are of only subgeneric impor- 
tance. But they serve to emphasize the fact that the unspecial- 
ized Asiatic Colobid Monkeys form four distinct groups, each 
having a characteristic type of juvenile coloration. The young of 
certain Semno pithecus of India, not treated now, are dark brown 
or blackish brown. Those of the other genera will be dealt with 
successively. 
Most species of Langurs inhabit the tropical lowlands but a 
species has been observed among snow-blanketed fir trees of the 
Himalayas at 11,000 feet (Forbes). The Snub-nosed Monkeys,. 
Rhino pithecus, also withstand extremely cold climates. 
The Capped Leaf Monkeys, genus Trachy pithecus, typified 
by the Negro Monkey of Java, T. pyrrhus, though they are 
distinguished from Presbytis, the Sureli Leaf Monkeys, only 
by average differences in the skulls, agree with one another in 
the color of the young, which is uniformly light brown or 
"golden red," with the tail dusky, in contrast to the black and 
white young of Presbytis. 
This group, widely distributed in the Sunda Islands, is rep- 
resented on the continent by T. obscurus, found in the Malay 
Peninsula, peninsular Siam, Tenasserim, and Cochin-China. 
Another species, T. phayrei of Arakan, reaches upper Burma, 
Yunnan, north Tenasserim, Siam, and Indo-China from Laos 
1 Opinion 114, The International Rules of Zoological Nomenclature. 
