_Brachyurus calvus_, Is. Geoffr., C. R., xxiv., p. 576 (1847); id., Arch.
Mus., v., p. 560 (1845); Castelnau, Expéd. Amér. Sud, Mammif., p. 17, pl.
4, fig. 1 (1855); W. A. Forbes, P. Z. S., 1880, p. 646; Beddard, P. Z.
S., 1887, p. 119, pl. xii.
{178}_Ouakaria calva_, Gray, Cat. Monkeys Brit. Mus., p. 62 (1870).
_Pithecia calva_, Schl., Mus. Pays Bas, vii., p. 228 (1876).
_Pithecia alba_, Schl., t. c. p. 229.
(_Plate XVI._)
CHARACTERS.--Fur very long, straight, and shining from neck to tail. Face
scarlet; top of head nearly bald, greyish, passing into brown anteriorly
and at the sides, with bushy sandy whiskers meeting below the chin; throat
dark brown, mixed with numerous black hairs, the general tint being rich
chestnut-brown; back whitish-grey, with black hairs mixed with white ones,
which are in greater number. Under surface fulvous brown, darker on the
breast, where brown hairs are numerous; the same brown tinge is visible on
the arms, legs, the hinder region of the thighs, at the wrist, and ankle,
and especially on the tail; eyes reddish-yellow. Length, 18 inches.
Some species are paler than the above description, being pale sandy-white,
slightly rufous below and on the inside of the limbs.
Cæcum 10 inches long along its greater curvature, and not sacculated.
According to Mr. Beddard, _B. calvus_ and _B. rubicundus_ agree very
closely in external and in internal characters, while _B. melanocephalus_
differs more in external characters from the other two than they do from
each other.
DISTRIBUTION.--Opposite Fonteboa; banks of the Japurá river west of its
mouth. This species appears to be confined to the triangle formed by the
union of the Japurá river and the Amazon. It does not pass east of Ega, nor
does it cross to the south of the Amazon, but keeps to the forests of the
low lands to the north of that boundary and south of the Japurá.