68 W. BLAXLAND BENHAM. 



the " lateral parieto-occipital/^ aud is coutiuuous with the 

 gyrus occipitalis primus^ which bends round the mediad ex- 

 tremity of the AfFenspalte. 



The gyrus occipitalis secundus (0 2) (deuxieme pli de pas- 

 sage externe) lies behind the AfFenspalte (in fact, is the opercu- 

 lum) and curves round its laterad extremity, becoming con- 

 tinuous with the " angularis." 



The third occipital gyrus lies below the oblique fissure (the 

 sulcus occipitalis inferior), and also passes into the third tem- 

 poral gyrus. 



The calcarine fissure just cuts the edge of the occipital 

 lobe, but is more extensive on the left than on the right hemi- 

 sphere. 



8. The Sylvian Fissure. 



The Sylvian fissure in "Sally's" brain is less vertical than 

 in the brain figured by Miiller, though, as Beddard has re- 

 marked, it is more vertical than in common chimpanzees. 

 The " Sylvian angle " in Dr. Cunningham's sense is 55° in 

 " Sally ;" the brain received from Professor Herdman has 

 rather a smaller angle, viz. 50°, whilst normally it is, according 

 to Cunningham, 54"5°. 



With regard to the " anterior limb" of the Sylvian fissure, 

 Beddard has quite rightly figured it as a short, nearly hori- 

 zontal fissure (PI. 23, fig. 2, F. s. a.) . A comparison of a series 

 of chimpanzee's brains led Cunningham to believe that it is 

 the anterior boundary of the fronto-parietal operculum, aud 

 therefore is the homologue of the ''ramus asceudens" in man. 

 He gives reasons for his conclusion that in Troglodytes the 

 only opercula covering the island of Reil are the fronto-parietal 

 and the temporal. The two anterior ones, frontal, and orbital 

 of man, are absent ; and he suggests that part of the orbital 

 lobule in the ape may represent the island of lleil in man. 



In " Sally " the insula is distinctly limited anteriorly by a 

 portion of the frontal lobe, which is at a much higher plane 

 than the insula, and separated from it by a deep fissure; but 

 it does not seusibly overlap the insula. However, in other 



