64 W. BLAXLAND BENHAM. 



behiud, without, in the majority of cases, reaching the mesial 

 border; the latter is the sharply descending end of the arch- 

 like " fissura interparietalis." Ecker's view, originally shared 

 by Cunningham (' Journ. Anat. Physiol./ 24), is now combated 

 by him, chiefly, it appears, on embryological grounds, partly 

 on those of comparative anatomy. (3) He would regard the 

 transverse occipital as merely a portion of the '' intra-parietal 

 s\ stem " which has nothing to do with the AfFenspalte. It is 

 due to the bifurcation, in fact, of the ramus occipitalis ; the 

 AfFenspalte, according to him, is only very rarely represented 

 in man. The " fissura perpendicularis externa " of Bischoff 

 makes its appearance in the human foetus about the fifth month 

 (according to Ecker and Cunningham); it is a "complete" 

 fissure impressing itself upon the ventricle, so that the outer 

 wall is bulged inwards by it. Some time later, apparently 

 during the sixth month, it disappears. Now all these authorities 

 are agreed that this external perpendicular fissure of the human 

 foetus is the homologue of the " AfFenspalte " of the ape. But 

 it is only a transient furrow, though " complete," and its place 

 is occupied later on (seventh or eighth month) by the terminal 

 bifurcation of the intra-parietal fissure, which is not a " com- 

 plete " fissure, that is, it does not leave its impress upon the 

 wall of the ventricle ; this second or replacing fissure becomes 

 the " transverse occipital.^' 



For these and other reasons Cunningham denies the possi- 

 bility of the suggestion that the latter fissure can be the homo- 

 logue of the AfFenspalte. 



Nevertheless it must be borne in mind that with regard to the 

 "completeness" of the Afi'enspalte, Cunningham (p. G9) "cannot 

 tell whether or not it (the elevation of the wall of the ven- 

 tricle) exists in the anthropoid brain. Specimens of these are 

 so valuable that I am unwilling to destroy those I have got, even 

 in a determination of a point of this importance." He has 

 only observed the bulging inwards of the outer wall of the 

 ventricle at the bottom of the AfFenspalte in the Sooty Mangaby 

 and in Cebus. 



As the Oxford Museum possesses several chimpanzees' brains, 



