188 



SlH. I. JS. BBBDAEU ON THE 



[Mar. 6. 



The animal wheii dead weighed 5 lb. 9 oz., there being no undue 

 distention of the stomach and alimentary canal with food. The 

 weight of the fresh brain was 4 oz. It was preserved first of all 

 in weak spirit (about 45 per cent.), and then, after 24 hours and 

 removal of the pia mater, transferred to strong spirit. 



With this treatment the brain seems to have altered very little 

 from the conditions observable in life. There is no suggestion 

 in the appearance and direction of the sulci of any changes. 

 I was therefore very much surprised to see the relations of the 

 cerebellum to the cerebrum, which are apparent in the accompany- 

 ing drawing (fig. 1). The cerebrum not only completely covers 

 the cerebellum, but extends for some way beyond it. With even 

 a liberal discount for contraction (of which, however, I do not see 

 the need), it is difficult to understand the brain-cast — of the accuracy 

 of which there can be no question — prepared by Sir W. Flower, 

 save on the hypothesis of an abnormality '. 



Fig. 1. 



<s_h 



Brain of Siauiang. Inner view of left hemisphere. 



M.P.O., mesial parieto-occipital fissure; CA., calcarine : OPT., optic nerve: 



OL„ olfactory. 



The Sylvian fisaurt seems to call for no particular remark. The 

 anteriorly directed fronto-orbital ' fissu ire is well developed, and the 

 exposed island of Jteil is extremely conspicuous. Tins is, however, 

 by no means a peculiarity of Hyhhates syndactylus as compared 

 with other Gibbons. 



The parieto-occipital fissure. — I take it that the fissure lettered 

 P.O. represents the parieto-occipital fissure of other Apes plus the 

 Simian fissure. It will be observed that on both sides of the brain 

 the Simian fissure, instead of terminating without reaching the 

 mesial surface of the brain, as is often the case with Anthropoid 

 Apes, bends forward and joins the parieto-occipital (fig. 2, p. 189). 



1 Dr. Keith has pointed out to me that the overlapping of the cerebellum 

 by the centrain is a characteristic of youth, and that the brain-ca-st studied b\ 

 •Sir W. Flower was therefore that of an old animal. 



