4. LAGOTDRIX. 45 



Like A. Belzelmth ; but the underside of the tail is as black as the 

 upper, the pale colour of the inside of the amis does not come 

 down so near tho hands, and the fur is much longer and spreads 

 out in all dLrections on the head and body. 



B. Fur soft, silky. Lower jaw inodemtely dilated behind. Hair of head 

 tunied backwards. 



3. BRACHYTELES. 



Hair woolly, soft ; of head short, directed backwards. Cutting- 

 teeth equal, small ; canines short ; grinders very thick, (juadran- 

 gular. Septum of the nose rather narrow. Thumb rudimentary 

 or wanting. Claws compressed. Tail very strong. 



Brachyteles (partly), Spii', Bras. p. 36, 1823 ; Slack, I. c. p. 513. 

 Eriodes, /. Geoff. Mem. Mus. xviii. 



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, Geo_ff.Ann. Mus. xiii. p. 270. Ei-iodes arachnoides, 



Is. Geoff. Mem. 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. Mamm. p. 72. 

 Eriodes tuberifer, I. Geoff. I. c. xii. p. 271. Brachyteles macro- 

 tarsus, Spi.r, Bras. p. 3G, t. 27. Eriodes hemidactylus, /. Geoff. 

 I.e. xiii. p. 270. B. hj-poxanthus, Gray, List Mamm. B. i)/. p. 11. 



Hah. Brazil. 



Thumb more or less rudimentary ; the species have been divided 

 into three on this account by M. I. Geoffrey ; sometimes there 

 is a thumb on one hand and none on the other. See Slack, I. c. 

 p. 514. 



4. LAGOTHRIX. 



Hair soft, wooUy, black. Tliumbs 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. 



Lap:othrix, Geoff. Ann. Mus. xix. p. 100, 1812. Gastriuiar<rus, Snix, 

 Bras. 1823. 



Slow, gregarious, meek ; often walking on their hind legs. 



