4. LAGOTHRIX. 45 



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

 upper, the pale colour of the inside of the arms docs not come 

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

 out in all directions on the head and body. 



D. Fur soft, silky. Lower jaw moderately dilated behind. Hair of head 



turned backivards. 



8. BRACHYTELES. 



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

 teeth equal, small ; canines short ; grinders very thick, quadran- 

 gular. Septum of tho nose rather narrow. Thumb rudimentary 

 or wanting. Claws compressed. Tail very strong. 



Brnchyteles (partly), Spit, Bras. p. 3G, 1823 ; Slack, I. c. p. 513. 

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



Gregarious in the woods of Central America. 



•tv 



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. Eriodes arachnoides, 



Is. Geoff. Mem. Mus. xvii. Brachyteles arachnoides, Gray, List 



Mamm. B. M. ! 



Var. with a woll-dovolopod thumb, young. Dark brown, sides 



of face whito. -"• ■"'• 



Var. -with rudimentary thumb. B. M. 



Ateles bypoxanthus, Pr. Max. Abbild. t.; Iuthl ; Desm. Mamm. p. 72. 

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

 tarsus, Spix, Bras. p. 3G," t. 27. Eriodes bemidactylus, /. Geoff. 

 I. c. xiii. p. 270. B. bypoxanthus, Gray, List Mamm. B. M. p. 11. 



Ilab. Brazil. 



Thumb more or less rudimentary ; tho species have been divided 

 into three on this account by M. I. Geoffroy ; sometimes thcro 

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



Lagotlmx, Geoff. Ann. Mus. xix. p. 106, 1812. Gastrimargus, Spix, 

 Bras. 1823. 



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



