MAMMALIA. 
41 
tal 3G. Facial angle GO degrees ; the head round with a short 
muzzle; forehead somewhat prominent; the occiput projecting 
behind ; the ears rounded; the os hyoides not prominent; the 
tail prehensile and hairy all over. 
Cebus fatuellus. — The Horned Sapajou. 
Plate IV. fig-. 8. 
Fur of the face reddish-brown, chestnut on the back, r paler on 
the sides, bright red on the belly, extremities and tail brown ; 
with two strong brushes of hair elevated on the base of the fore¬ 
head ; claws longish, and somewhat blunted. About the size of 
a half-grown cat. Inhabits Guiana. 
Section 2d. —Sagoins. —Tail long, but not prehensile. 
Genus 12. — Callithrix. — Cuvier . 
Generic Character. —Incisors canines |-j, grinders to¬ 
tal 36. facial angle GO degrees ; head small and rounded; ears 
long, mis-shapen ; tail somewhat longer than the body, covered 
with hair, and not prehensile ; body slender, in proportion to 
its size. 
Callithrix sciureus. — The Squirrel Monkey. 
Plate IV. fig. 9. 
Colour of the fur, bright gold yellow; hands and feet orange; 
the head round ; nose blackish ; orbits of the eyes flesh-colour ; 
ears hairy and ill formed; under parts whitish; tail very long, 
with a black tip. Size of a squirrel. Inhabits Cayenne and 
Brazil, South America. 
Genus 13. —Aotus.— Humboldt. 
Generic Character. —Incisors *, canines J—J, grinders jj-jj; to¬ 
tal 3G. Head large and round; muzzle short; eyes very large 
and approaching; nostrils separated by a very thin partition; 
ears small; tail as long as the body, covered with hair, but not 
prehensile. 
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