512 ANIMAL PHYSIOLOGY. 
The gray matter of the brains of the higher vertebrates is 
distributed as masses of ganglionic cells internally, and as a 
fairly uniform. layer over its surface. The cerebrum of man 
Fig. 369.—Lateral views of the brains of a rabbit, a pig. and a chimpanzee, drawn of nearly 
the same absolute size (Huxley). The rabbit’s brain is at the top; the pig’s. in the middle; 
the chimpanzee’s. lowest. Ol, olfactory lobe; A, frontal lobe ; B, occipital lobe ; C, tem- 
poral lobe ; Sy, the sylvian fissure ; In, the insula; S. Or, supra-orbital; S. F,M.F, re 
superior, middle, and inferior frontal gyri; A. P, antero-parietal ; P. P, I foaeinbec ret 
gyri; R, sulcus of Rolando ;' P. Pl,*postero-parietal lobule ; O, Pf, external pe ndicular 
or occipito-temporal sulcus: An, angular 3: 2, 3,4, annectent gyri; 4.7, M.T, P. qT, 
the three temporal, and S. Oc, M. Oc. I. Oc, the three occipital gyri. = 
weighs about three pounds on the average, that of the male 
being a few ounces (four to six) heavier than that of the female. 
The individual and race differences, though considerable, are 
aa 
