CEREBRAL CONVOLUTIONS — " SALLY." 71 



the junction of the fissure with the s. frontalis secundus (/^.) ; 

 the upper portion of this vertical fissure appears to represent 

 the ''ramus horizontalis " (A.). The prsecentralis superior 

 {p. c. s.) is a very well marked, transversely-placed furrow, 

 seen best in the view of upper surface. The lower end lies 

 behind the upper end of the ramus horizontalis. It is in free 

 communication with the distinct "sulcus frontalis primus" 

 (or superior) (f^.), which runs straight forwards and bifurcates 

 anteriorly. 



Lying in front of this is an oblique furrow, with its posterior 

 end directed towards the mesial fissure, which it almost 

 reaches : the anterior end bifurcates, and lies in front of, but 

 mediad of, the end of the sulcus frontalis primus. What is 

 this fissure ? 



It is represented in the left hemisphere by a smaller and 

 unbranched furrow. 



Is it a portion of the frontalis primus ? or is it a representa- 

 tive of the " sulc. frontalis mesialis " ? 



According to Cunningham, the disjointed portions of the 

 sulcus frontalis primus lie in exactly the opposite direction, 

 i. e. the posterior ends of each are laterad (outside) of the ante- 

 rior end of the preceding. From the fact that these disjointed 

 pieces are slightly variable, it will perhaps be safer to leave 

 the matter open, for hitherto the " s. frontalis mesialis " is 

 characteristic of the human brain, and has not been met with 

 in the ape. 



In front of this, again, is a curved furrow which is probably 

 another portion of the s. front, primus. 



The s. frontalis secundus (or inferior) has been carefully 

 identified by Cunningham, and he has conclusively shown that 

 the sulcus rectus of the monkey's brain is the homologue of 

 the s. frontalis inferior, and not of the s. frontalis medius 

 as Eberstaller believed. Cunningham therefore agrees with 

 Gratiolet's views, which are at variance with some more 

 modern views, that the inferior frontal lobe is present in the 

 apes. 



In "Sally" the sulc. frontalis inferior (secundus) (fig. 12, p.) 



