78 W. BL AX LAND BENHAM. 



The s. frontalis medius (/. m.) is a simple fissure passing 

 forwards nearly horizontally, its hinder end having precisely 

 the typical position below the ramus horizontalis, from which 

 it is separated by a deep-lying gyrus. 



The s. frontalis secundus (/".) is in two parts, the chief of 

 which lies just below the s. frontalis medius and passes forwards 

 to the frontal lobe, giving rise to the " s. fronto-marginalis " 

 of Wernicke. The other part of the fissure to which I have 

 referred above is in continuity with the s. prsecentralis inferior. 



On the right side of this brain (figs. 43 and 45) the furrows 

 on the frontal region have rather a different arrangement. The 

 sulcus praecentralis superior {p. c. s.) is single and of consider- 

 able length, occupying the position of the two furrows of this 

 name on the left side. It lies parallel to the fissure of Rolando, 

 and at about half its length is joined by a longitudinal fissure, 

 which appears to be the main part of the sulcus frontalis 

 primus (/^.). 



The sulcus prsecentralis inferior {p. c. i.) is also fairly well 

 developed ; upwards it lies in front of the sulcus praecentralis 

 superior, and below it nearly reaches the Sylvian fissure, from 

 which it is separated by a deep gyrus. Passing from it ante- 

 riorly are two horizontally directed furrows, the upper of which 

 appears to be the ramus horizontalis (A.), the lower and shorter 

 is probably a part of the sulcus frontalis secundus (/".). 



Where, now, is the sulcus frontalis medius? It ought to lie 

 below the ramus horizontalis. There is a furrow in this 

 position which curves upwards round the anterior end of the 

 ramus horizontalis, part of which possibly represents this 

 sulcus frontalis medius. Unfortunately the brain is so ill pre- 

 served in this region that the exact arrangement of fissures 

 on the lower part of the frontal lobe cannot accurately be 

 made out. 



Orang No. 2 (figs. 39—41). 

 In Rollestou's specimen the upper part of the right hemi- 

 sphere has been removed, but is preserved. The following is 

 the arrangement : — On the left side (figs. 39 and 41), lying in 



