QUADRUMANA. 



Pig. 127. 



Vertical section of the brain of the Orang-cetan. 

 (After W. Vrolik.) 



compare these distinct views of the brain of 

 the Orang-cetan with those of the Baboon 

 represented by LEURET * (figs. 128, 129, 130), 



207 



the inferiority of these to the Orang-cetan is so 

 manifest, that it needs scarcely any further 

 explanation. In the first instance, it appears 

 that the brain or the Cynocephalus, and, ac- 

 cording to the observations of TIEDEMANN, 

 we could say the same for all the monkeys 

 inferior to the Chimpanzee, the Orang-cetan, 

 and the Gibbons, differs from the brain of 

 man : 



1 . By a greater breadth in proportion to the 

 length, and consequently by a less elliptical 

 and more triangular form. 



2. By less development of the hemispheres 

 of the brain, which do not cover the whole 

 cerebellum. 



3. By a smaller number and greater sym- 

 metry of the convolutions, and less deep 

 anfractuosities. 



4. By less development of the corpus stria- 

 turn, thalamiis nervorum opticorum, corpus cal- 

 losum, and septum lucidum. 



Figs. 128, 129, 130. 



Views of the brain of the Baboon. (After Leuret) 



5. By the want of digitations on the convex 

 margin of the cornu Ammonis. 



6. By the want of the eminentia digitalis 

 (pes Hippocampi minor). 



7. By the disposition of the corpora albi- 

 cantia, which are united in one mass. 



8. By the absence of calculous granulations 

 in the glandula pineafis. 



9. By less development of the cerebellum 

 and of thepons VAROLII. 



* F. Leuret, Anat. Comp. du Systkme nerveux 

 considers dans ses rapports avec Pintelligence, Paris, 

 1839, 8vo. 



All these manifestations of inferiority are 

 not so distinct in the brain of the Orang-cetan, 

 which approaches more to that of man. This 

 approximation consists in : 



1. The more elliptic, and consequently 

 more human-like form of the brain. It is a 

 most interesting fact, that the deviation, in the 

 descending line, begins already in the Gibbons, 

 the brain of which has a more triangular form, 

 and less developed anterior lobes, than the 

 brain of the Orang-cetan. 



2. The larger cerebral hemispheres, which 

 are protracted behind the cerebellum. 



