_Alouatta_, Lacép., Mém. Inst., iii., p. 490 (1801).
_Mycetes_, Illig., Prodr. Syst. Mamm., p. 70 (1811).
_Stentor_, Geoffr., Ann. Mus., xix., p. 107 (1812).
The characters of the genus _Mycetes_, which is the only one of the
sub-family, are the same as those given above under the sub-family heading.
The genus contains six well-recognised species. According to Mr. Wallace
the red and black species of the Amazon have females of the same colour as
the males. Humboldt also remarks, speaking of the thousands of Arguatoes
(_M. seniculus_) which he observed in the provinces of Cumana, Caracas, and
in Guiana, that he never saw any change in the reddish-brown fur of the
back and shoulders, either in isolated individuals or whole troops. Many of
the species, however, do have the sexes of quite different colours.
The Howlers are semi-nocturnal in their habits, uttering their cries late
in the evening and before sunrise, and also on the approach of rain.
(_Wallace._)
When a _Mycetes_ is shot it always hangs to the tree, even if quite dead,
and does not fall till the muscles of the feet and tail relax.
The species of this genus range through Central America, Colombia, and the
Amazonian region, to Southern Brazil, Bolivia, and Paraguay.