I t is the subject, however, of considerable variation, the most extreme variety
being that in which the general colour of the animal, instead of being black, becomes
wholly pale yellow (27. entelloides, Is. Geoff. St.-Hil.). I t may be observed, however,
that, even in these very pale animals, which as in 27. hoolock are generally females,
the paler colour of the hands and feet can to a certain extent be detected. Between
these two well-defined extremes every variety of colour is exhibited by the species,
but the characteristic specific markings of the face, hands, and feet are preserved.
In some individuals the index and middle toes of the foot become united by a
web, as in 27. syndactylus.
Its voice is perfectly distinct from that of 27. hoolock.
I t appears to be confined to Arracan, Lower Pegu, Tenasserim, and to the
Malayan peninsula.
H y l o b a t e s p i l e a t u s , Gray.
Hylobates pileatus, Gray, Proc. Zool. Soc. 1861, p. 186, pi. sari, ; Cat. Monkeys and Lemurs, B M
1871, p. 10.
Hylobates lar, Myth, Journ. As. Soc. Beng. vol. xliv. 1875, ex. no. p. 2.
The individuals of this species are generally distinguished by a black area on
the top of the head resembling a cap, and by the chest being almost wholly of the
same colour, which, however, in some instances extends on to the throat and belly.
The back of the head, the upper surface of the trunk, the limbs, the circumference
of the black spot on the crown, are greyish, usually paler in the latter area, all the
remaining portions being black. Other specimens are all white, with the exception
of the back which is brownish, and the top of the head and the chest which are
black; while some are brownish, with the chest, belly, and sides of the face black,
the throat also partaking more or less of the latter colour. In some examples the
whole of the under parts are black and the whiskers are white.
I t is a most variable Gibbon, and the circumstance that it is to a certain extent
resembled by 27. agilis, 27. leuciscus, and 27. mulleri, in the distribution of their
colours, has suggested to the minds of some zoologists, and with a show of
probability, that they may all ultimately prove to be referable to one species.
Inhabits Siam.
H y l o b a t e s l e u c o g e n y s , Ogilby.
UOnhe, Tabraca, Hist. Civile et Nat. de Siam, vol. ii. 1771, p. 808.'
Hylobates leucogenys, Ogilby, Proe. Zool. Soc. 1840, p. 20,* Blylh, Journ. As. Soc. vol. x. 1841,
p. 838; Martin, Nat. Hist. Quadrumana, 1841, p. 445 (plate and fig. of skull); Is. Geoff!
St.-Hil. Comptes Rendus, 1842, vol. xv. p. 717, Arch, du Mus. vol. ii. 1848, p. 585; Schinz,
Syn. Mamm. vol. i. 1844, p. 28; Gervais, Hist. Nat. des Mammif. 1854, p. 54; Wagner!
Schreber, Saugeth. Suppl. vol. v. 1855, p. 20; Gray, Cat. Monkeys and Lemurs, B. M 1870*
P-11. -
This species is entirely black, with the exception of the area below the ears, the
cheeks, and the part of the throat immediately behind the chin, which are white.
The specimens in London and Paris exactly agree with each other.
This species inhabits Siam (Paris Museum), and is probably closely allied to
those forms of 2Z. pileatus in which the animals are wholly black with the exception
of the whiskers; so that it seems to be so closely related to 27. pileatus tha t the two
may ultimately prove to be identical.
H y l o b a t e s l e u c i s c u s , Schreber.
The Wow Wow, Camper, Allgemeene Vaterland. Letterfn. i. p. 18.
The Long-armed Ape, Pennant, Hist. Quad. vol. i. 3rd ed. 1793, pi. xxxviii.
The Long-armed Ape (var. B), Pennant, Hist. Quad. vol. i. 3rd ed. 1798, p. 184.
Le Moloch, Audebert, Hist. Nat. des Singes, l re fam. sect. ii. pi. ii.
The Long-armed Aye (white var.), Shaw, Gen. Zool. vol. i. pt. 1, 1840, p. 12, pi. vi.
Le Gibbon cendre, Latr. Hist. Nat. Buffon (Sonnini ed.), vol. xxxv. (1809) p. 207, pi. x.
Simla leucisca, Schreber, Säugeth. tab. iii. b, 1775.
Pithecus leuciscus, Geoff. St.-Hil. Ann. du Mus. vol. xix. 1812, p. 89.
Hylobates leuciscus, Kuhl, Beitr. zur Zool. 1820, p. 6; Desmarest, Mamm. 1820, p. 51; P. Cuvier
Diet, des Sc. Nat. xxxvi. 1825, p. 289; Lesson. Man. de Mamm. 1827, p. 81; Griffith
An. Kingd. vol. v. 1827, p. 6; Bory de St. Vincent, Diet. Class. d'Hist. Nat. vol. xii. 1827,
p. 284; G. Cuv. Rbg. An. vol. i. (nouv. ¿d.) 1829, p. 90; Fischer, Syn. Mamm. 1829, p. 12;
Is. Geoff. St.-Hil. Belanger's Voy. aux Ind. Orient., Zool. 1884, p. 26; Compt. Rend,
vol. xv. 1842, p. 716; Cat. Mdthod. des Mammif. 1851, p. 7; Arch, du Mus. vol. v. 1852,
p. 534; Müller, Tijdsch. voor Natuur. Gesch. en Phys. vol. ii. 1835, p. 827; Schlegel, Essai
sur la Physion. des Serpens, Pt. Gen. 1837, p. 237; Waterhouse, Cat. Mamm. Mus. Zool.
Soc. Lond. 1888, 2nd ed. p. 4; Wagner, Schreber, Säugeth. Suppl. vol. i. 1840, p. 78,
pi. iii'. b; Lesson, Sp. des Mammif. 1840, p. 51; Martin, Hist. Quad, or Monkeys, 1841,
pp. 416, 417, 436; S. Müller, Verhandl. over de Zool. van den indisch. Arch. 1839 44,
p. 15; Gray, Hand-list Mamm. B. M. 1848, p. 2; Cat. Monkeys and Lemurs, B. M. 1870
_ p. 12; Müller und Schlegel, Verhandl. 1839—44, p. 48; Blyth, Journ. As. Soc. Beng. vol. xiii!
1844, p. 465; Ibid, vol. xliv. 1875, ex. no. p. 4; Cat. Mamm. As. Soc. Mus. 1863, p. 5;
Schinz. Syn. Mamm. vol. i. 1842, p. 31; Cantor, Journ. As. Soc. Beng. vol. xv. 1846, p. 173;
Gervais, Hist. Nat. des Mammif. 1854, p. 58 (fig. of head); Wagner, Sehreber, Säugeth.
Suppl. vol. v. 1855, p. 16; Dahlbom, Stud. Zool. Fam. Regn. An. 1856, pp. 73, 74; Giebel,
Zeitschr. ges. Ntrwiss. 1876, p. 168 (skull); Bischoff, Abh. Bayr. Ak. Wiss. vol. x. 1870,
j>. 119, 5 plates (pi. i. head).
General colour, uniform grey, paler on the lower region of the b a ck; area
around the face paler than the other parts, with the exception of the frontal
streak, which is more or less conspicuous. The top of the head is occasionally
blackish or dark brown, forming a kind of cap, but in others it is very obscure; the
fingers and toes tend to blackish. The fur is dense, profuse, and rather long and
woolly.
Inhabits Java.
The Bornean Gibbon (27. mulleri, Martin) appears to be closely allied to this
species, but the materials a t our disposal are not yet sufficient to determine whether
the two are specifically identical.
I t is, however, noteworthy that two animals corresponding to 27. leuciscus and
to 77. mulleri, now living together in the Calcutta gardens, both utter undistin