MORPHOLOGY OF THE CEREBRAL CONVOLUTIONS. 345 



The mesial occipito-frontal convolution, M.O.F,=the gyrus fornicatus + the in- 

 ternal inferior pli de passage. 



The mesial portion of the superior occipito-frontal convolution, OF J ,= the mesial 

 surface of the superior frontal, F\+the paracentral lobule+the lobulus precentralis+ 

 the internal superior pli de passage where this is present. 



The lateral surface of the superior occipito-frontal convolution, F 1 , = the 

 lateral surface of the first or superior frontal + the anterior central convolution. 



The middle or second occipito-frontal co7ivolutwn, F 2 , = the middle or second 

 frontal convolution, F 2 ,+the posterior central+the superior parietal+the superior 

 external pli de passage. 



The inferior or third occipito-frontal, F 3 , = the third frontal + the inferior 

 p arietal convolution, P 2 P 2 ', + the deuxieme pli de passage externe. 



The mesial occipito-temporal convolution, M T, = the lobulus lingualis + the 

 gyrus hippocampi. 



The inferior occipito-temporal convolution, T 3 , = the lobulus fusiformis (of 

 some writers) + the third temporal convolution + the quatrihne pli de passage 

 externe. 



The second or middle occipito-temporal, T 2 , = middle temporal + the troisieme 

 pli de passage externe. 



The superior occipito-temporal, T 1 , = superior temporal convolution + the 

 deuxieme pli de passage externe (in common with F 3 ) . 



The plis de passage are considered the connecting folds passing from the con- 

 volutions to the occipital lobe, the reasons for which we have already pointed out. 



The relations of the fissures of the occipito-frontal and temporal lobes are as 

 follows : — 



The mesial occipito-frontal fissure, m. o. f,= the calloso-marginal + the fissures 

 of the paracentral and quadrate lobules + the fissure between the internal superior 

 and inferior plis de passage (when it exists) . 



The superior or first occipito-frontal fissure, o f, 1 = the first frontal + the cen- 

 tral or fissure of Rolando. 



The inferior or second occipito-frontal fissure, o f 2 , = the inferior frontal + the 

 fissura interparietalis. 



The relations to the nomenclature of the occipito-temporal lobe are not altered. 



The mesial occipito-temporal fissure, m. o. t, = the occipito-temporalis inferior 

 or collateral fissure. 



The superior occipito-temporal, o t 1 , = the first temporal. 



The inferior occipito-temporal, o t 2 , = the second temporal. 



In the occipital lobe : — 



The superior occipital fissure, o 1 , = fissura occipitalis. 



The inferior occipital fissure, 2 , = ex-occipital fissure. 



As regards the fissures and convolutions of the occipital lobe itself these have 

 been considered in such a different light from that of most previous observers that 

 it is not possible to strictly compare them. 



