HOWLING MONKEYS. 
1S3 
the projecting muzzle. This obliquity of the face is connected with the flattening 
of the hinder part of the skull, already referred to; and is so marked that the 
profile inclines backwards almost in a straight line from the muzzle to the crown. 
Like all American monkeys, except the spider-monkeys and some of their allies, the 
howlers have well-developed thumbs. Their face is naked, with the muzzle very pro¬ 
jecting ; the naked parts being surrounded by a fringe of long hair on the forehead, 
cheeks, and chin. On the forehead this long hair may be directed either backwards 
or forwards, but that of the whiskers and beard always hangs down. The hair of 
the body, although shorter than that surrounding the face, is relatively long. 
The howlers are especially abundant in Brazil, but they also range into Central 
America. They are represented by a considerable number of species, but since 
these are chiefly distinguished from one another by the colour of their hair, and 
there is considerable individual and sexual 
variation in this respect, it is in some cases 
difficult to decide as to which variations we 
ought to regard as indicating distinct species, 
and which merely as local races. The food of 
these monkeys is stated to consist entirely of 
leaves. 
Humboldt says that, when travelling in 
the neighbourhood of the Orinoco, the rising of 
the sun was always heralded by the cries of 
the howlers. Frequently this traveller and his 
companion, Bonpland, observed troops of them 
moving slowly in procession from tree to tree. 
A male was always followed by a number of 
females, several of the latter bearing their 
young on their shoulders. The uniformity 
with which they perform their movements is 
described as being very remarkable. According 
to the observations of Humboldt, as detailed 
by one of his biographers, whenever the 
branches of neighbouring trees do not touch 
one another, the male, who leads the party, 
suspends himself by the naked prehensile part 
of his tail, and, letting fall the rest of his body, swings himself till in one of his 
oscillations he reaches the neighbouring branch. The whole file performs the same 
movements on the same spot. The Indians told the travellers that when these 
monkeys filled the forests with their howling there was always one that chanted, 
as leader of the chorus. During a long interval one solitary and strong voice 
was generally distinguished, till its place was taken by another of a different pitch. 
Writing in relation to a specimen of one of these monkeys, brought to him 
when travelling on the Lower Amazon, Mr. Bates observes that “ the howlers 
are the only kind of monkeys which the natives have not succeeded in taming. 
They are often caught, but they do not survive captivity many weeks. The one 
of which I am speaking (apparently a female of the black howler), was not quite 
HEAD OF THE VERA CRUZ HOWLING MONKEY. 
(From Sclater, Proc. Zool. Soc.) 
