82 W. BLAXLAND BENHAM. 



S. or Sy. Sylvian fissure. S'. Its anterior limb. «/. Ramus ascendens of the 

 anterior limb of the Sylvian fissure. */'. Ramus horizontalis of the anterior 

 limb of the Sylvian fissure, iemp. Temporo-sphenoidal lobe. f. Parallel 

 fissure, tc. Sulcus fronto-marginalis of Wernicke. 



Fig. 1. — Dorsal view of a brain of an ordinary chimpanzee. (From a 

 photograph, reduced.) The operculum is well developed, and conceals the 

 "Affenspalte." 



Fig, 2. — Dorsal view of the brain of " Sally," for comparison with Figs. 1 

 and 3. The operculum is very feebly developed, and the " AfFenspalte " 

 is fully exposed. The parieto-occipital fissure is divided into two, more dis- 

 tinctly on the right than on the left side. The position of the fissure of 

 Rolando is to be noted, compared with Fig. 1. The frontal lobes are very much 

 fuller than in the ordinary chimpanzee, so that the shape of the hemispheres 

 more nearly resemble those of man. (From a photograph, reduced.) 



j'jQ, 3, — Dorsal view of the "Hottentot Venus;" from a photograph of 

 Gratiolet's figure, reduced to the same size as those of the chimpanzee. 

 YiG. 4. — Side view of " Sally's " brain, from a photograph. 

 Fig. 5. — Front view of an ordinary chimpanzee's brain, rather larger than 

 natural size. The orbital region of the frontal lobe on each side is greatly 

 compressed, forming a " keel" (^.). 



Fig. 6. — Front view of " Sally's " brain, in order to exhibit the almost 

 entire absence of the "keel." Much less of the temporo-sphenoidal lobe 

 is seen. 



Fig. 7. — Front view of a European brain, for comparison with Fig. 6. 

 Reduced. The keel is very similar to that in " Sally." 



Fig. 8. — View of the " island of Reil " of the right side in a chimpanzee 

 (Oxford Museum, No. 947 /.)• The temporo-sphenoidal lobe has been pulled 

 downwards. S/. The " ramus ascendens," and S/'. Ramus horizontalis of the 

 anterior limb of the Sylvian fissure, /r. op. Frontal operculum, orb. op. 

 Orbital operculum. (From a photograph.) 



Fig. 9. — View of a longitudinal section of a chimpanzee's brain (Oxford 

 Museum, No. 947/). (From a photograph.) The section passes along the 

 posterior cornu (p. cormi) of the lateral ventricle, and is intended to siiow 

 the relation of the Afi'enspalte to the wall of the ventricle, cal. av. Portion 

 of the calcar avis. 



Figs. 10 — 15 illustrate the surface anatomy of " Sally's" brain. They are 

 drawn life size, and the position and shape of the sulci are represented with 

 the greatest care. 



Fig. 10. View of the left hemisphere, as seen when looked at from above 

 and slightly laterally. The arrangement of the sulci on the frontal, 

 parietal, and occipital lobes are shown. 

 Fig. 11. View of the right hemisphere, as seen when looked at from 

 above and slightly laterally. 



