104 CEBUS 



variation in the color of pelage among individuals of the three species, 

 VARiEGATUs, FATUELLUS, cUid MACROCEPHALUS, and in somc cascs they 

 resemble each other so closely, that unless a definite locality accom- 

 panies the example, it is impossible to decide to which species it should 

 be referred, and definite localities are rarely given by the Authors of 

 the earlier part of the nineteenth century. 



Cebus FATUELLUS PERUANUS Thomas. 



Cebus fatuellus peruanus Thos., Ann. Mag. Nat. Hist., VII, 7th 

 Sen, 1901, p. 178. 



Type locality. Marcapata, Huoynapata, Inambari Valley, S. E. 

 Peru. Type in British Museum. 



Genl. Char. Like C. fatuellus, but horns not quite so much 

 developed, and the yellow in the arms absent. 



Color. Precisely like C. fatuellus as described, but arms from 

 shoulders to elbow same color as back. Black tufts on crown not so 

 long. Ex type British Museum. 



Measurements. Skull: occipito-nasal length, 79; zygomatic width, 

 64; intertemporal width, 39; palatal length, 29; breadth of braincase, 

 51; median length of nasals, 15; length of upper molar series, 21; 

 length of mandible, 53; length of lower molar series, 27. Ex type 

 British Museum. 



There are two specimens of this form both immature, and indis- 

 tinguishable in color from C. fatuellus, except that the upper part of 

 the arms is like the back instead of being yellowish. I attribute this 

 to age, or possibly season, and the shorter tufts on head to age or 

 possibly sex, as both the specimens are females. The examples may 

 probably prove to be the young of C. fatuellus. 



Cebus maceocephalus Spix. 



Cebus macrocephalus Spix, Sim. et Vespert. Bras., 1823, p. 3, 

 pi. I; Wagn., Schreb., Saugth. Suppl., I, 1840, p. 208; V, 

 1855, p. 96; von Pelz., Zool.-Bot. Ges. Wien, 1883, Beiheft, 

 p. 12; Goldi, Os. Mamm., Bras., 1893, p. 43, (note). 



Cebus robustus Tschud., Faun. Peruan., 1840, pp. 41, 45, (nee 

 Kuhl, nee Wied). 



Cebus {Eucebus) macrocephalus Reichenb., Vollstand. Naturg. 

 Aflfen, 1862, p. 56, pi. VI, fig. 87. 



Cebus fatuellus Forbes, Handb. Primates, I, 1894, p. 211, (Part.). 



