MAMMALIA. 495 
The genus Protopithecus is composed of a fossil species found in Brazil 
and nearly related to Cullithrix. 
In the genus Pithecia the tail is tufted, whence the name of fox-tailed 
monkeys, which is commonly given to them. These animals live in small 
troops of ten or twelve individuals, usually residing in the outskirts of forests 
bordering rivers. ‘They display a morose and savage temper, menacing the 
offender with their teeth upon very slight provocation. 
The genus Cebus comprehends the monkeys known as sapajous, sajous, 
&c., whose tail’ is covered with fur to its extremity. The latter is prehen- 
sile, but not so delicate an organ of touch as in the following genera. The 
thumb is present on all the extremities. The species are for the most part 
of small size, and are very lively and docile in their temper as well as 
active in their movements; somewhat capricious, however, in their dispo- 
sition. ‘They live in troops in their native forests, feeding on fruits, grains, 
egos, and insects. They have been termed weepers, from the plaintive, 
piping noise which many of them utter. The capucin (@ capucinus) is 
represented in pl. 118, figs. 2 and 8. A fossil species of this genus is 
described from Brazil. 
The genus Lagothric (silver-haired monkeys) has a round head, resem- 
bling Ateles, a thumb to the anterior hands, and the tail rather naked. 
The species live in the interior of South America. 
The genus Aéeles (four-fingered monkeys) is distinguished by the great 
length, slenderness, and flexibility of their limbs, whence the appellation of 
spider monkeys, and by the prehensile power of their tail. The anterior 
thumbs are either totally or nearly hidden under the skin. Their move- 
ments on the ground are wanting in firmness, even when they are resting 
on all the four extremities. Their general aspect is rather that of crawlers 
than of walkers. They tread on the inner edge of the fore paws and on 
the outer edge of the hind paws, and endeavor to assist themselves by 
attaching the tail to any object as they proceed. They often assume the 
erect attitude, however, and then use the tail asa means of balancing them- 
selves. The proper place for these monkeys, however, is among the branches 
of the forest, where their movements are very rapid, easy, and uncon- 
strained, as they swing from branch to branch by means of their spider-like 
limbs and their prehensile tails with the greatest agility. The tail is an 
organ of touch as well as of prehension; its end is destitute of hair, and 
furnished beneath with a sensitive skin. It is capable of seizing small 
objects with great address. These animals are said to introduce the 
extremity of their tail, as a feeler, into the fissures and hollows of trees, for 
the purpose of hooking out the eggs or other substances. 
The genus Mycetus (alouattes), or howling monkeys, is distinguished 
from the last by their greater size and the diminished length of their hmbs; 
by the presence of a thumb which is, however, not opposable. The head 
is pyramidal. The howlings uttered by the troops of these monkeys are 
described by travellers as astounding. They are usually sent forth early 
in the morning, at sunset, and during the darkness at night; but they are 
also heard when the overclouded sky threatens an approaching storm. In 
699 
