274 STUDY OF BRAIXS OF SIX EMINENT SCIENTISTS AND SCHOLARS. 



Gyres dfthe Frontal Lohc. iLateral Surface). — The precentral gyre of this half is 

 rather broader than that of the right half and at its middle it is interrupted by the 

 central-supercentral anastomosis. The superfrontal gyre is well defined in its caudal 

 half, its lateral boundary being lost in the complexity of the prefrontal region. The 

 medifrontal gyre is wide and the subfrontal is larger than the corresponding region on 

 the I'ight side. The left frontal lobe throughout is far more complexly fissured and is 

 considerably differentiated from the common type. 



Fissures of the Parietal and Occipital Lobes. Lateral Surface. The Post- 

 central Fksural Complex. — The postcentral fissure, 8 cm. in length, describes an 

 irregular zig-zag course anastomosing ventrad with the subcentral and caudad with 

 the parietal. The T-shaped subcentral is small and anastomoses with both the central 

 and postcentral fissures. The parietal fissui'e bears an unusual relation to the paroc- 

 cipital. Instead of joining the latter by a cephalic ramus, the parietal lies for the 

 most part laterad of the paroccipital and then, with an abrupt raesal sweep, the 

 parietal joins the paroccipital opposite the occipital incisure. 



A well-marked intermedial fissure which joins the parietal demarcates the exten- 

 sive marginal g3're from the angular while a second smaller "intermedial" lies 

 between the intermedial proper and tlie episylvian. 



Mesal Surface. — The precuneal is of irregular zygal shape and several smaller 

 fissures mark the surface of the precuneus. A small cuneal fissure running parallel 

 with the calcarine marks the cuneus. 



Gyres of the Parietal and Occipital Lobes. lateral Surface. — The postcentral gyre 

 is very broad in its middle third. The parietal is of good width, Ijut comparatively 

 short, while the paroccipital occupies an odd position owing to the cephalic turn of 

 the dorsal part of the occipital fissure. The marginal is quite wide ; at its transi- 

 tion into the supertemporal gyre it is characterized by a distinct operculation. It is 

 to this overlapping that the shortening of the sylvian fissure is chiefly due. The 

 angular gyre is fairly complex and is characterized by its overlapping of the parietal- 

 paroccipital. 



Mesal Surface. — The comparative smallness of the cuneus and the larger size of 

 the precuneus are to be noted. 



Fissures of the Temporal Lobe. — The supertemporal fissure is represented by two 

 segments, a short cephalic and a longer caudal one ; the latter is quite tortuous and 

 ramified. In the medi and subtemporal regions the transverse tendency of the fissures 

 does not permit of a clear determination of the medi and subtemporal fissures as they 

 are commonly seen. The collateral fissure is more clearly marked. The postrhinal 

 is merely indicated by a groove. 



