166 HYLOBATES 
WHITE-CHEEKED GIBBON. 
Type locality. Siam. Type in British Museum. 
Geogr. Distr. Siam. 
Color. Area below ears, cheeks, throat beneath chin white; rest 
of pelage black; face and ears black. Ex type British Museum. 
Measurements. Head and body, 448.8; foot, 139.7. Ex type 
British Museum. 
HYLOBATES GABRIELLI Thomas, 
Hylobates gabrielli Thos., Ann. Mag. Nat. Hist., 1909, 8th Ser., 
p. 112. Type in British Museum. 
Type locality. Lang Bian, Annam. Altitude 1,500 feet. 
Color. Face black; sides of under jaw and throat beneath chin, 
ochraceous; all the rest of pelage, head, upper and under parts of 
body, chin, limbs, hands and feet, jet black. Ex type British Museum. 
Measurements. Total length, 560; foot, 150. Skull: total length, 
116; occipito-nasal length, 97.2; intertemporal width, 50; breadth of 
braincase, 65.1; Hensel, 79.4; zygomatic width, 75.7; median length 
of nasals, .86; palatal length, 42.2; length of upper canines, 18.8; 
length of upper molar series, 27; length of mandible, 75.7; length of 
lower molar series, 31.5. Ex type British Museum. 
A single specimen of this rather curiously marked Gibbon is in 
the British Museum, and is different from any example I have met 
with. Whether it represents a phase of pelage not yet seen of some 
species, or is that of an undescribed species, cannot as yet be determined, 
and we must wait for additional specimens before it can be satisfac- 
torily decided. The H. HENRIcI Pousargues comes from a locality 
considerably to the north of the present form, but it may have a range 
sufficiently great to bring it into Annam. 
The type of H. HENRICI certainly does not resemble the Annam 
Ape, but the animals of this genus are accustomed to vary in such 
an extraordinary degree, that it necessitates bringing together a con- 
siderable number of examples before the specific value of any style 
of coloring in their coats can be determined. At present this Annam 
specimen in its coloring is unique. It seems to be nearest to H. LEu- 
COGENYS, from which it differs only in the color of sides of under 
jaw, throat and beneath chin, which is ochraceous instead of white. 
HYLoBATEs LEucIscus (Geoffroy). 
Pithecus leuciscus E. Geoff., Ann. Mus. Hist. Nat. Paris, 2.1, 
1812,.. Du 89. 
