THE ANNALS 
AND 
MAGAZINE OF NATURAL HISTORY. 
No. 105. OCTOBER 1845. 
XXII.—On the Howling Monkeys (Mycetes, Iiliger). 
By J. BE. Gray, Esq., F.R.S. &c. 
Mvcu attention has been paid by various zoologists to the spe- 
cies of Monkeys of the Old World, but as yet little consideration 
has been devoted to those of the western hemisphere, and pro- 
bably zoologists have been deterred from attending to them on 
account of the difficulty of the subject. 
Humboldt in his ‘ Zoological Observations,’ Prince Maximilian 
and Spix m their works on Brazilian zoology, are almost the 
only modern authors who appear to have written on them from 
the personal examination of the specimens, having moreover en- 
joyed the advantage of observing them in their native forests. 
Spix described one of the species, M. Caraya, as bemg black 
im the male and yellow in the female and young; and Prince 
Maximilian observes that the males and the specimens of M. ur- 
sinus from the more northern regions of Brazil are rufous or fer- 
ruginous, whilst the female and aihose from the more southern 
regions are brown or blackish brown, and Lichtenstein describes 
the young of this species as blackish. Cuvier observes, that there 
is very little difference between M. ursinus and M. seniculus. 
We have been fortunate at the British Museum in having pro- 
cured a considerable number of specimens of this genus, and 
as I find amongst those that have been received at the same time 
or from the same localities the two sexes of nearly the same colour, 
and the young and adult equally so, L am inclined for the pre- 
sent to regard them as species; at the same time I must confess 
that some of the specimens of the same apparent species vary 
considerably in tint, and that some of the black species have so 
many red hairs scattered amongst their fur when it is bent back 
and examined, as to make one almost doubt if the black are not 
another state or local variety of the red ones. 
Under these difficulties, [ think it is desirable that the various 
Ann. §& May. N. Hist, Vol. xvi. R 
