4, LAGOTHRIX. 45 
' Like A. Belzebuth ; but the underside of the tail is as black as the 
upper, the pale colour of the inside of the-arms does not come 
down so near the hands, and the fur is much longer and spreads 
out in all directions on the head and body. 
B. Fur soft, silky. Lower jaw moderately dilated behind. Hair of head 
‘ turned backwards. 
3. BRACHYTELES. 
Hair woolly, soft; of head short, directed backwards. Cutting- 
teeth equal, small; canines short; grinders very thick, quadran- 
gular, Septum of the nose rather narrow. Thumb rudimentary 
or wanting. Claws compressed. -Tail very strong. 
Brachyteles (partly), Spix, Bras. p. 86, 1828; Slack, lc. p. 518. 
Eriodes, I. Geoff. Mém. Mus. an : ; : 
Gregarious in the woods of Central America. 
Brachyteles arachnoides. B.M. 
Ashy brown; face flesh-coloured; base of tail and vent often 
ferruginous; organ of generation dark red-brown. Females more 
ashy. ; 
Var. without any thumb. B.M. 
Ateles arachnoides, Geoff. Ann. Mus. xiii. p. 270. Eviodes arachnoides, 
Is. Geoff. Mém. Mus. xvii. Brachyteles arachnoides, Gray, List 
Mamm. B. M.! 
Var. with a well-developed thumb, young. Dark brown, sides 
of face white. B.M. 
Var. with rudimentary thumb. B.M. 
Ateles hypoxanthus, Pr. Max. Abbild. t.; Kuhl; Desm. Mamma. p. 72. 
Eriodes tuberifer, Z. Geoff. 1. c. xii. p. 271. Brachyteles macro- 
tarsus, Spiz, Bras. p. 36, t.27. Eriodes hemidactylus, I. Geoff. 
lc, xiii. p. 270. B. hypoxanthus, Gray, List Mamm. B. Mp. 11. 
Hab. Brazil. - : : ; 
Thumb more or less rudimentary; the species have been divided 
into three on this account by M. I. Geoffroy; sometimes there 
is a thumb on one hand and none on the other. See Slack, l. c. 
p. 514. , : 
4, LAGOTHRIX. 
Hair soft, woolly, black. Thumbs well developed. Limbs short, 
proportionate. Chin and crop sparingly hairy. Hair of crown 
short, directed backwards. Throat-bone scarcely apparent externally. 
Lower jaw moderately dilated behind. Nostrils oblique, rather 
close below. : 
Lagothrix, Geoff. Ann. Mus. xix. p. 106, 1812. Gastrimargus, Spiz, 
Bras, 1823.: 
Slow, gregarious, meek ; often walking on their hind legs, 
