170 AY LOBATES 
Color. The type of H. acizis F. Cuvier, or one so styled on label 
and received in the Paris Museum in 1821, is yellowish white on head, 
upper parts and sides of body, limbs and hands; feet pale brown; 
throat and under parts of body pale ochraceous, or an orange shade; 
top of head tinged with buff. The specimen is doubtless faded and is 
much soiled with the dust of nearly a century. 
Measurements. Skull: occipito-nasal length, 89; Hensel, 80; 
zygomatic width, 65; intertemporal width, 48; median length of nasals, 
10; length of upper molar series, 25; length of mandible, 70; length of 
lower molar series, 28. 
This is one of the most variable species of the genus HyLoBATEs, 
and in color ranges from the typical yellowish white described above 
to jet black, with perhaps a narrow white superciliary stripe. These 
many variations, as is to be expected, have produced numerous syno- 
nyms, and not a little confusion, especially among the earlier writers 
who could not be cognizant of the fact that these striking differences 
were of no specific value, but merely evidences of individual eccen- 
tricities. Thus the melanistic style received the name of rafflesi; and 
another variable form that of variegatus. Like H. Lar, the index and 
middle toes are sometimes united by a web. 
HYLOBATES PILEATUS Gray. 
Hylobates pileatus Gray, Proc. Zool. Soc. Lond., 1861, p. 136, pl. 
XXI; Reichenb., Vollstand. Naturg. Affen, 1862, p. 174, figs. 
482-484; Matschie, Sitzungsb. Ges. Natur. Freund., Berl., 
1893, p. 209. 
Hylobates agilis S. S. Flower, Proc. Zool. Soc. Lond., 1900, p. 313. 
Type locality. Cambodgia. Type in British Museum? 
Geogr. Distr. Cambodgia; Paknam Kabin, Siam; Cochin China. 
Color. Top of head from forehead to rear of crown, sides of face 
before ears, throat and under parts of body to end of abdomen jet 
black; superciliary stripe, hairs around the black crown, and inner 
side of arms and legs yellowish white; rest of pelage grayish buff 
inclined to brownish on outer side of arms. 
Measurements. Head and body, 440; foot, 150. Skull: occipito- 
nasal length, 86; Hensel, 75; zygomatic width, 60; intertemporal width, 
48; median length of nasals, 9; length of mandible, 67; length of 
upper molar series, 25; length of lower molar series, 30. 
This is another wonderfully varied species as regards the dis- 
position and extent of the black. The description given above is 
