1899.] 



BRAIN OE THE GORILLA. 



67 



this is partly responsible for the enormous brain literature that 

 exists. I propose in the follomng pages to malie my descriptions 

 as short as possible and to forbear from much comment and 

 comparison. 



As regards the general shape of the brain, I have no remarks to 

 offer except as to the keel upon the ventral or orbital surface of 

 the frontal lobes. I am disposed to think the existence of this 

 keel is a normal feature of the Grorilla's brain as it is of that o£ 

 the Chimpanzee. In the two best-preserved brains at my disposal 

 it was very clearly marked. I laid some stress upon the difference 

 in this particular which the brain of " Sally " showed from that of 

 other Chimpanzees. I am now not at all convinced that a larger 

 series would bear out such a distinguishing character. I infer from 

 a remark of Dr. Benham's that the Orang's brain is also believed to 

 be without this keel. The keel was well marked in one of three 

 Oraug brains in my possession. 



The Sylvian fissure and island of Reil. — The most noteworthy 

 point that I observed in relation to these portions of the brain is 



Fig. 2. 



Braia of Gorilla belonging to Royal College of Surgeons. Lateral view. 



I.R. Island of Reil. S.f.o. Fronto-orbitalis. 

 Other letters as in fig. 1. 



the occasional exposure of a portion of the island of Reil. This 

 is seen in fig. 2, which represents one side of the brain belonging to 

 the Royal College of Surgeons. It was visible also on the other side 



