Species aiid Subspecies of Mammals. 101 



upper tooth-vow mucli more curved; zyi^omaMc arcli wider 

 and intertemporal width greater ; bullae narrower and longer. 



Geogr. distr. Upper waters of tiie Amazon in Ecuador, and 

 Peru. 



Colour. General colour like S. sciurea, with the back 

 darker, that of" the type being tawny and black on the dorsal 

 region; golden yellow and black on the flanks ; arms above 

 elbows dark grey washed with yellow; legs paler; underparts 

 yellowish white; the forearms, hands, and feet tawny; head 

 and tail like S. sciurea^ 



Measurements. Size similar to xS'. scjwrea. Skull: occipito- 

 iiasal length 64:'5 mm. ; zygomatic width 43 ; intertemporal 

 width 32; length of nasals 11; width of brain-case 36; 

 height of brain-case above zygomata 35 ; palatal length 19 ; 

 length of upper molar series 16 ; width of palate between 

 canines 12 ; width of palate between last molars 13. 



B.M. no. of type SO. 5. 6. 15. 



While the general colour of this a;nimal resembles that of 

 S. sciurea from the east coast of South America, it is at once 

 noticeable by its much darker forearms, hands, and feet. 

 The greatest differences, however, between the two forms jue 

 exhibited in the skulls and in the large teeth of the present 

 species. The brain-case has quite a ditferent shape, being 

 long and narrow, with an elevated forehead sloping rapidly 

 downward to the occiput, which is narrow and rouiuled. The 

 palate is wider throughout its length; the teeth much larger, 

 the canines longer and stouter. Several examples were 

 obtained in the i) pe locality and others from the Jurua River, 

 a tributary of the Amazon, and from Marcapata, Peru. 



Genus Callicebus. 



Callicebus usto-fuscus, sp. n. 



7^1/pe locality. " Brazil." 



Gen. c/iar. Allied to C. cvpreus, but much darker in 

 colour; teeth much larger; palate longer and narrower; 

 brain-case wider ; space between pterygoid processes and 

 buUai and the width of basioccipital throughout its length 

 greater. Practically the skull is larger in every way and 

 more massive. Mandible longer antl heavier, and the depth 

 of the ramus greater. 



Colour. General hue above burnt-umber, the hairs being 

 slaty-grey at base, then annulatod with two bands of slate- 

 and two of clay-colour, and a dark tip. Face naked, black; 

 top of head a mixed dark ochraceous rufous and black, the 



