412 J. J. KEEGAN 



independent yulciis occipitalis pokiris. If the interpretation of 

 Landau is correct, its prominence would be an indication of a 

 greater proportionate development of the area striata in the 

 same manner as the sulcus lunatus. 



The fossa parieto-occipitalis is quite typical of E. Smith's 

 description in the left hemisphere. The gyrus intercuneatus is 

 about 5 mm. in height and separates widely the s. paracalcarinus 

 and the s, limitans praecunei. It is traversed by an independent 

 sulcus incisura which appears superficially on the lateral surface, 

 separate from the termination of the sulcus limitans praecunei 

 in the gyrus arcuatus posterior. The s. paracalcarinus under- 

 mines the posterior wall of the fossa, becoming superficial along 

 the border of the hemisphere posterior to the gyrus arcuatus. 

 The fossa of the right hemisphere is less typical. The gyrus 

 intercuneatus is faintly indicated, the deepest part of the incisura 

 being formed by the sulcus paracalcarinus. The s. limitans 

 praecunei incises the lobulus praecuenus. 



The sulci limitantes areae striatae are easily identified by the 

 delimitation of the area striata. 



The insula, as far as could be determined, presented nothing 

 unusual in its fissuration. The operculation was complete in 

 both hemispheres. 



SUMMARY 



The detailed study of the fissures and convolutions brings a 

 number of points to attention. First is noted the striking differ- 

 ence between the two hemispheres in almost every fissure or 

 region examined. This variation is so great that a comparison 

 of hemispheres is of very little value in the interpretation of 

 sulci, which method proved so valuable in the interpretation in 

 the Negro brain. A similar fact of asymmetry is stated by 

 Appleton ('10) to represent an agreement with European cere- 

 bra in general and a contrast with supposedly lower types of 

 cerebra. Many writers have called attention to the asymmetry 

 of the cranium, brain, and intracranial venous sinuses sepa- 

 rately, but comparatively little work has yet been done to study 

 the co-relation of these asymmetrical conditions the one to the 

 other or to explain their origin. E. Smith ('07), in a note upon 



