The Sakis are characterised by having their lower incisor teeth inclined
forward at their summits somewhat as among the Lemurs; and separated from
the long canines by an interspace. The molar teeth are small; the tail,
which in some is long, in others short, is non-prehensile. The nostrils
are, as usual, far apart, and the thumb is well developed. The ears are
large. Great differences in the character of the fur exist in the group:
some species having long hair over the whole body, others on the chin and
cheeks; some are well bearded, while others again are quite bald.
The Sakis are divided into two genera, a short-tailed group (_Brachyurus_),
containing the Uakarí Monkeys, and a long-tailed {174}section, the Sakis
(_Pithecia_). Their various species are restricted to the great equatorial
forests of South America.