32. Frerp Museum oF Natura History — Zootoey, Vor. X. 
genotype of Dirias. Evidently the dental characters are not corre- 
lated with the length of the tibia and foot in any natural association of 
species, and since it is difficult to see generic significance in the relative 
shortness of the tibia and foot, the recognition of Dirias as a distinct 
genus is open to serious question. 
Cebus apella leucocephalus Gray. 
Seven specimens, Orope, Zulia, Venezuela; collected by N. ‘Dear. 
born. One of these (No. 16,567) has been compared with the type of 
Cebus leucocephalus in the British Museum. The type is somewhat 
larger and its pelage slightly fuller and longer than in our specimen, 
but the color is practically identical, the only difference being in the 
color of the under side of the tail which is slightly darker in the type. 
Comparison has not been made with Cebus albijrons and it is there- 
fore somewhat of an assumption to use the name leucocephalus as that 
may possibly prove to be a synonym of albifrons. However, the 
belief that leucocephalus differs from albijrons is encouraged by the 
original description* of albifrons, which states that the forehead is 
black, whereas in our specimens it is brown. Moreover, the face in our 
specimens is scarcely white, but pale brown. The locality assigned 
to leucocephalus by Gray is simply ‘‘Columbia’’+— but its agreement 
with our specimens makes it probable that the exact locality was at 
least in northeastern Colombia and probably in western Venezuela 
near the coast. This is the more probable since a well-distinguished 
form (malitiosus) inhabits the Santa Marta region. 
* As follows: ‘‘ Simia albijrons, ex albo cinerascens, vertice nigro, facie caerulea, fronte et 
orbitis niveis, cruribus et brachiis fuscentibus.” 
t P.Z.S., 1865, p. 827. 
