ANATOMICAL STRUCTUEE OF ANTHROPOID APES. 199 



developed ; and the island of Reil and its fissures were 

 almost uncovered. This formation is almost the 

 same as that of the brain of anthropoids. The two 

 central fissures of Rolando were close together, or 

 less deeply impressed on the edge of the hemi- 

 spheres than is normally the case, and forming no 

 joint angle. Large and deeply marked pre-central 

 fissures seemed to represent the central fissures. 

 The intra-parietal fissures, diverging outwardly 

 further than in man, received the parieto-occipital 

 fissure, a structure in conformity with the typical 

 brain of apes. The transverse occipital fissure 

 became in this case a deep fissure like the simian 

 fissure, crossing the occipital lobes, and almost 

 completely dividing them from the parietal lobes. 

 The so-called Fissura calearina, to which we have 

 referred above, had its origin on the upper surface 

 of the occipital lobe, then joined the parieto- 

 occipital fissure, and went directly into the hippo- 

 cam pal fissure (Fissura liipijocampi) on its right 

 side. This abnormal structure is also in conformity 

 with the typical brain of apes. The first occipital 

 convolution is divided from the upper parietal lobes 

 by the parieto-occipital fissure. Gratiolet asserts 

 that this formation occurs in many species of apes. 

 The upper temporal convolution was remarkably 

 reduced on both sides, possessing only an average 

 width of 5 mm. This characteristic reminded 

 Krause of the brain of the chimpanzee. In that 

 animal the upper temporal convolution is always 

 reduced. Krause therefore asks whether some human 

 brains may not possess the typical structure of apes 



