NERVOUS SYSTEM. VERTEBRATA. 449 



eye no trapezoid body is apparent, although it seems to be 

 partially exposed in specimen D. 661 (left side). 



The mesial geniculate body seems to be much more 

 prominent than it is in Man a prominence possibly 

 associated with the larger size of the auditory nerve. 



Beddard (Proc. Zool. Soc. 1899, p. 65), in a memoir 

 based upon these four specimens and one other, gives a 

 list of the literature o the Gorilla-brain. His figures 1, 2 

 and 4 represent this specimen. 



[In drawing up a comparison between the brains of the 

 Chimpanzee and Gorilla, Kiikenthal and Ziehen place this 

 specimen (formerly labelled " Troglodytes savagii ") among 

 the Chimpanzees, and state that they have had no oppor- 

 tunity of studying the brain of a Gorilla! Jenaiscbe 

 Zeitschr. f. Naturwiss., Bd. xxix. 1894.] 0. C. 1338 le. 



D. 659. The brain of a Gorilla (Anthropopithecus gorilla), sub- 

 divided by a mesial sagittal section. 



In this brain we find the usual Anthropoid arrangement 

 of the anterior insular region, instead of the more human 

 disposition presented by the preceding specimen. The 

 superior limiting (Marchand's "opercular") sulcus emerges 

 from the Sylvian fissure and approaches without even 

 appearing to join the long fronto-orbital (anterior limiting) 

 sulcus. Nor are the lips of these sulci opercular as in that 

 specimen. In other words, the condition found in this 

 specimen is that which is usual in the three great Anthro- 

 poids. Unlike the arrangement in the last specimen, the 

 sulci arcuatus and rectus are here blended to form a single 

 sulcus, as in the Gibbons. The superior frontal and 

 superior precentral sulci resemble those of the previous 

 specimen, except that they are less regular. There are also 

 a few small furrows which can only represent the sulcus 

 frontalis mesialis, which Cunningham regards as dis- 

 tinctively human. 



The parallel sulcus resembles that of the last specimen, 

 as also does the intraparietal excepting the fusion with its 

 ramus postcentralis superior on the left side. 



The mesial portion of the Simian sulcus seems to have 

 been pushed backward into a peculiar V-shape by the 



VOL. II. 2 



