CEEEBRAL CONVOLUTIONS — " SALLY." 57 



from the calcarine fissure — but presenting no lateral branches, 

 nor gyri coming to the surface. 



This seems to be the simplest condition, and closely resembles 

 the arrangement in the lower monkeys ; some other of our 

 specimens of chimpanzees exhibit this condition ; in others we 

 have seen the gyrus iutercuneatus interfering with the continuity, 

 and giving rise to two more or less independent fissures. 



In a brain at the College of Surgeons (No. 1338, 1 a*), the 

 left hemisphere exhibits this simple arrangement, whilst the 

 right (1338, I a) possesses the more complicated condition. 



In the human brain, the separation of the parieto-occipital 

 fissure into two appears from Dr. Cunningham's researches 

 to be rare, but in the brain (950) exhibited as a typical 

 human brain in the Oxford Museum, and represented here by 

 fig. 16, we have on the left side an arrangement repeating, 

 I believe, that in " Sally," namely, the uprising of the gyrus 

 intercuneatus (a.) so as to separate a lateral parieto-occipital 

 (fat. p. 0.) from the remainder (m. p. o.). On the right hemi- 

 sphere the parieto-occipital cuts into the upper surface for 

 about an inch, forming the true "external parieto-occipital," and 

 this part is continuous with the vertical portion. But in 

 the left hemisphere there lies in front of the " transverse 

 occipital fissure " or Afienspalte, between it and the vertical 

 part of the parieto-occipital, a transversely placed fissure 

 about an inch in length [lat. p. o.), bounded anteriorly by a 

 gyrus which is partially overlapped by the " arcus parieto- 

 occipitalis.'^ 



5. The Parietal Convolutions. 

 The fissure of Rolando (" fissura centralis'^) has the usual 

 wavy character ; it does not enter the Sylvian fissure on either 

 side, nor does it pass on to the mesial face of the hemisphere. 

 The distance of the upper extremity of the fissure from the an- 

 terior end of the hemisphere (between vertical plates) is 45 mm. 

 There appears to be some confusion in Beddard's paper with 

 regard to the position of this fissure of Rolando. In the plate 

 xxiii, fig. 3, the index line from f. r. is carried to the upper 



