210 PROCEEDINGS OF THE ACADEMY OF [1892. 



inferior temporal convolutions, passes partly into the angular convolu- 

 tion and partly into the occipital lobe. The inferior temporal convolu- 

 tion, PL XI, fig. 2V, lying below the inferior temporal fissure, passes 

 into the occipital lobe. The fifth lobe, insula or island of Reil, 

 lying between the frontal, parietal and temporal lobes, is but little 

 developed in the brain of our Gorilla, much less so than in the brain 

 of the Chimpanzee described by the author. The insula, while 

 entirely covered by the operculum on the left hemisphere, is but 

 partly so in the right. Unfortunately the hemispheres were so 

 altered on the mesial surface in the hippocampal region as to render 

 impossible the demonstration of the lateral ventricle with its hippo- 

 campus major and minor, etc. Inasmuch, however, as the parts in 

 question were demonstrated by the author in the brains of the Orang 

 and Chimpanzee, as had been done i:)reviously by others, doubtless 

 they existed in the brain of our Gorilla. As to the remaining parts of 

 the brain of the Gorilla the medulla and pons did not present any espe- 

 cially noticeable peculiarites. The cerebellum, Pl.XII, fig. 4,however, 

 was not only absolutely but relatively smaller than that of Man or of 

 the Chimpanzee or Orang, and was entirely covered by the cerebrum, 

 the posterior or occipital lobes extending beyond the cerebellum to 

 an extent of several millimetres, and this though the brain had 

 been lying in alcohol for many months. 



The cerebellum was entirely covered, as was also the case in the 

 two other brains of the Gorilla already referred to as having been 

 too much altered to admit of description. It was equally well cov- 

 ered in the brain of the adult Gorilla sent many years ago by the 

 Rev. Mr. Nassau to Dr. Morton but which was unfortunately in such 

 a condition in other respects as to render it unfit for description. It 

 may be mentioned incidentally that the cerebellum of the Chim- 

 panzee is larger than that of either the Gorilla or Orang, and it 

 would appear that while it is entirely covered by the cerebrum in 

 the adult or nearly adult animal, it is partly uncovered by the 

 cerebrum in the young animal. At least of three Chimpanzees dis- 

 sected by the author, in the two young animals it was demonstrated 

 before the brain was taken out of the skull that the cerebellum 

 was not covered by the cerebrum, and the same condition was 

 observed in the brain of the young Chimpanzee dissected by Mr. 

 Arthur E. Brown, Superintendent of the Philadelphia Zoological 



