334 DE. G. ELLIOT SMITH ON 



pallium gradually slopes up to the general level of the pallium without any definite lip 

 to separate it from the rest of the surface. Toward the anterior extremity of the fossa, 

 however, an ill-defined ridge of cortex or lip makes its ajipearance just above and parallel 

 to the anterior rhinal fissure. In other words, a hoi-izontal depression about 1"5 mm. 

 broad is found immediately above the posterior half of the anterior rliinal fissure ; from 

 the anterior extremity of this depression a sulcus begins and extends obliquely upward 

 and forward toward the antero-superior corner of the hemisphere, where it terminates at 

 a point about 2 mm. from the apex and an equal distance from the mesial border of the 

 pallium. We may distinguish this sulcus by the designation /3. Upon the right 

 hemisphere of the same brain the fossa Si/lvii presents features which closely resemble those 

 upon the left hemisphere, and the sulcus 3 arises in the same manner, but does not extend 

 so near to the mesial plane. But in addition we find in this hemisphere a small oblique 

 sulcus, 9 mm. long, upon the dorsal aspect of the apex, just in front of the termination of the 

 sulcus /3. In the brain which Gervais figures the two hemispheres appear to be perfectly 

 symmetrical so far as the fossa Si/lvil and the sulcus j3 are concerned. The lips which 

 limit the fossa Si/lvil appear to be more prominent, and in addition there seems to be a 

 definite though faint lip bounding ih.G. fossa Si/lvii in front. As a result of the existence 

 of this anterior lip, the upper extremity of the fossa Si/lvii seems to be converted into a 

 definite fissm-e, which arches obliquely upward and backward and then pursues a course 

 of about 10 mm. in the caudal direction parallel to the great interhemispheral cleft 

 (vide Gervais, pi. i. figs. 3 and 3 a). So far as we can judge from Gervais's figures, the 

 sulcus /3 is quite independent of the fossa Sylvii and the fissura rhinalis, but begins at a 

 distance of 2 mm. above the anterior rhinal fissure and extends obliquely forward to 

 cross on to the mesial surface of the hemisphere at a distance of about 4'5 mm. from the 

 apex of the pallium. Unlike the condition in our type-specimen, the sulcus /3 appears to 

 be symmetrical in the two hemispheres. Forbes represents the sulcus /3 in one of his 

 specimens extending into continuity Avith the rhinal fissure ; but he remarks that the 

 area in front of the sulcus /3 (which, in accordance witii the extraordinary suggestion of 

 Broca, he calls the " frontal lobe ") is connected to the fodsa Sylvii (Broca's " lobule 

 sous-sylvien ") by a small, sometimes deep, bridging fold. 



At a distance of about 6 mm. from the mesial plane there is, upon the dorsal surface 

 of each hemisphere, a longitudinal sulcus which we may distinguish as y. The anterior 

 extreaiity bends obliquely outward and downward, and is 13 mm. distant from the apex 

 of the hemisphere. The posterior extremity approaches quite close to the posterior 

 border of the hemisphere, and bends outward for a short distance imrallel to it. 



In the specimen figured by Gervais the anterior extremity of this sulcus does not bend 

 laterally, but otherwise it agrees Avith our type-specimen. In all cases the sulcus 7 

 approaches very close to the sulcus f3, but without actually joining it. 



The broad elliptical area which lies between the posterior lip of the ybss« ^_y/»w and 

 the posterior margin of the hemisphere is divided into two approximately equal j^arts by 

 a deep vertical sulcus, whicli begins above at a point about 1; mm. (viewed in profile) 

 below the sulcus 7, and ends below at about an equal distance above the ventral margin 

 of the hemisphere. Tiiis sulcus, which we may call I, is approximately symmetrical 



