I50 ALLEN’S NATURALISTS LIBRARY. 
reach. The expression of countenance in these small Mon- 
keys is intelligent and pleasing. This is partly owing to the 
open facial angle, which is given as one of 60°, but the quick 
movements of the head, and the way they have of inclining 
it on one side, when their curiosity is excited, contribute very 
much to give them a knowing expression. . . . Inmobility 
of expression of countenance, intelligence and general manners; 
these small Monkeys resemble the higher Apes far more than 
they do any rodent animal with which I am acquainted, not- 
withstanding their apparently low organisation in many 
points.” 
This description of the habits of the Negro Tamarin may 
be taken as representative of those of the various species of 
the genus, of whom only glimpses can be caught in their homes, 
which are the safe altitudes of the giants of the virgin forests 
of Brazil. 
THE CAPUCHINS, HOWLERS, AND SPIDER- 
MONKEYS, &c. FAMILY CEBID. 
This family embraces the typical Platyrrhine Monkeys, and to 
it belongs the great majority of the American species. As 
already pointed out (p. 127) their nose is flat, and the partition 
between the nostrils, which open sideways, is very broad, and 
separates them widely. ‘They are essentially quadrupedal, and 
walk with the soles of both pairs of limbs flat to the ground. 
The Spider-Monkeys occasionally, however, assume an erect 
posture. ‘‘ They all possess tails, and in some genera (e.g., 
Afeles) this organ becomes very flexible and muscular, and the 
under surface of its curled extremity is devoid of hair and 
highly sensitive. The tail thus modified is a powerful pre- 
hensile organ and serves for a fifth hand.” (Zwx/ey.) In these 
