376 Mr. 0. Thomas on 



where there is a difFerentiatlon of colour the dark part lies 

 in the centre. One other species, F. chinensis, has to be 

 taken into account; but apart from size, for it is smaller, 

 F. chinensis may be distinguished by the ground-colour beinj^ 

 huffj not grey ; the shoulders are not noticeably more rufous 

 than the rest of the body, and the spots are much smaller and 

 more cleanly cut. 



I append tiie measurements of the skulls of F. euptilura^ 

 F. Ricketti^ and F. clmiensi's. 



Breadth 

 between 

 Greatest inner 

 breadth of roots Length 



Greatest Basil Palatal Zygomatic brain- of car- of car- 

 length, length. length. Creadth. case. nasaials. nassials. 



mm. mai. mm. mm. mm. mm. 



F. euptilura, Ell.) ,,^ ^^ 



]i.M. 95.2.21.1. ^ ^^^ ^^ 



F. Ricketti. [ 



B M. 98.6.21.1. ) 

 F. chhiensis. I 88 



B.M. 2.6.10.9. ( approx 



39 70 47 27 11 



lOo 88 39 69 44 2o 10-5 



75 3-5 60 42 22 10 



L I . — Xe 10 Ma mnia Is fro m Chir iq u i. 

 By Oldfield Thomas. 



A FURTHEE collection received from Mr. H. J. AYatson, of 

 Boquete, Chiriqui, contains, besides examples of almost all 

 the species described from that locality by Mr. Outram Bangs, 

 specimens of the following new forms : — 



Cebus imitator, sp. n. 



Like C. liyiioleucus^ but the female with elongated frontal 

 tufts. 



Speaking first of the female only it may be described as 

 follows : — 



Size and colour in all respects as in C. hypoleucus, except 

 on the frontal region, where, as in certain of the South- 

 American species, the hairs are elongated to form prominent 

 frontal tufts which entirely alter the appearance of the face. 

 These hairs are about 40 mm. in length, and are therefore 

 very different from the short hairs covering the fiontals in 

 C. hypoleucus ; they are also of a distinctly brownish tinge, 

 markedly different from the white of the cheeks and throat. 

 "White fur on and surrounding the ears longer than in 

 C. hypoleucus — indeed the fur throughout, on body, limbs, 



