CEREBRAL CONVOLUTIONS — " SALLY." 73 



a small oblique furrow (h.), recalling the " prsecentralis 

 medius " of some authors. 



Cunningham in some cases finds in man the ramus hori- 

 zontalis nearly vertical, or composed of a forked furrow. This 

 he considers is merely an extreme condition to which the 

 term " prsecentralis medius" has sometimes been applied. 

 The other frontal furrows are normally developed. 



It may be worth while to refer to some of the variations in 

 the arrangement of these furrows in our other chimpanzee 

 brains. In most of them the ramus horizontalis is continuous 

 with the prsecentralis inferior; it is most characteristically 

 developed in the brain represented in figs. 33, 34. In fig. 38, 

 again, this latter furrow is very well developed, but has no 

 anteriorly directed horizontal branch. Probably the upper part 

 of it, together with the short posterior horizontal (h.) branch, 

 represents the ramus horizontalis. In fig. 28 the ramus 

 horizontalis is continuous with what appears to be a portion of 

 the frontalis primus. It is in both these cases more or less 

 vertical. 



The frontalis secundus {f^.) is continuous with the prsecen- 

 tralis inferior, except in fig. 28 and on the brain represented 

 at fig. 30. In the former the frontalis secundus is connected 

 with a downwardly directed vertical furrow, which is very much 

 more distinct in fig. 33. This condition may be compared with 

 that of an eighth month human foetus figured by Cunningham 

 on p. 250. 



In the brain represented in figs. 30, 34, on the right side 

 the prsecentralis inferior {p. c. i.) is provided with a large ramus 

 horizontalis (A.) composed of an anterior sagittal and a posterior 

 constituent directed obliquely upwards. The s. frontalis 

 medius (/. m.) and the "^ inferior " (/^.) are separate from the 

 prsecentralis and are nearly simple furrows ; but the "inferior'^ 

 bifurcates at its extremity. This bifurcation probably represents 

 the s. fronto-marginalis. S. frontalis primus (/^.) is in three 

 separate pieces, the hindermost being continuous, as usual, 

 with the s, praecentralis superior (/j. c. s.). 



On the left side of the same brain (fig. 33) a very peculiar 



