38 CEBIDE. 
18. Mxpas. Head with short hairs. 
19. SentocEenus. Head naked in front, hairy behind. 
Dahlbom arranges the prehensile-tailed monkeys according to 
their anatomical character, thus :— 
I. Muzzle obtuse, conical ; spinous processes of the lumbar vertebrae 
acutely triangular, directed more forward than the rest, nearly 
incumbent. 
a, Eyes very large, lateral; septum of nose narrow. Nyectipithecus. 
b. Eyes moderate, anterior ; septum of nose broad. Callithrix. 
Il. Muzzle blunt, truncated; spinous processes of the lumbar vertebrae 
trapeziform. 
a. Tail hairy all over. 
* Septum of the orbit membranaceous. Saimiri. 
** Septum of the orbit bony. Cebus. 
b. Tail-end bald. Ateles, Lagothrix, Mycetes, (Zool. Stud. p. 146.) 
Section A. Gymnura. Tail elongate, prehensile, strongly revolute, hairy ; 
under surface of the tip naked, callous. Grinders 3.3. 
Tribe I. MYCETINA. 
Head pyramidical ; face oblique; chin and crop gibbous, covered 
with long rigid hairs. Canines large. Lower jaw much dilated behind. 
Os hyoides very large, spongy. Thumb distinct. Claws convex. Tail 
very long. Ferocious, noisy before the rising and after the setting 
of the sun. Living on leaves of trees. 
1. MYCETES. 
Head pyramidical. Face and the lower part of the body nearly 
naked. Tail strong. Fingers very long. 
Mycetes, Idiger; Gray. Ann. § Mag. N. H. 1845, xvi. p. 217. Sten- 
tor, Geoff. Aluata, Lacép. Cebus, Eral. Aluatta, Slack. 
Spix describes the male and the female M. caraya as being black, 
and the young yellow. Prince Neuwied observes that the males 
and the specimens of M. ursinus from the more northern region of 
Brazil are rufous or ferruginous, while the females and those from 
the more southern regions are brown or blackish brown. Lichten- 
stein describes the young of this species as blackish. Cuvier observes 
that there is very little difference between M/, ursinus and M. seniculus. 
The specimens of the two sexes that are in the British Museum, 
received at the same time and from the same locality, are nearly the 
same colour, and the young and adults equally so; but some speci- 
mens of apparently the same species vary considerably in tint ; some 
of the black species show so many red hairs scattered among their 
yet Pads. 
