TROGLODYTES NIGER, THE CHIMPANZEE 569 



chimpanzee compares favorably with human specimens showing a low 

 degree of organization. The temporal lobe has convolutions and fissures 

 characteristic of the human bram. These fissures assume their typical posi- 



MG. 25315. DETAILED DIA(;KAM OF LEFT LATERAL SLKFACE OF BKAIN, 



CHIMPANZEE. 

 Key to Diagkam. obl., Oblongata; kamis, Ramus Posterior of Sulcus Temporalis Superior; SULC. 

 occip.. Sulcus Occipitalis; suLC. occip. lat.. Sulcus Occipitalis Lateralis; sulc. pruct. inf.. Sulcus Precen- 

 tralis Inferior; sulc. prect. sup.. Sulcus Prcccntralis Superior; sulc. ret. inf., Sulcus Retrocentralis 

 Inferior; s. T. mkd.. Sulcus Temporalis Medius. 



tions with a general tendency to extend into the parietal lobe. The sulcus 

 simiarum is somewhat longer than in gorilla, coming well down behind the 

 caudal extremity ol the temjjoral lobe. 



The eonvoiutional design on the lateral surface of the occi])ital lobe is 

 notably feeble. Only a few of the secondary fissures make their appearance in 

 this region. On the mesial surface, however, the cuneus shows somewhat 

 greater comjjlexity in its coiuolutional pattt'rn even than the human bram. 

 This is due to the fact that a dee]) annectent gyre in the upper extremity of 

 the simian fissure comes to the surface and thus interrupts the continuit\- of 



