34(5 



PLATE III. (Addendum.) 



Drawings to show some variations in the disposition of the sulcus crueiatus hominis. All have 

 been made from right hemispheres, and the field includes the lobulus paracentralis and the hinder 

 part of the callosomarginal sulcus. 



In drawing 1, the sulcus crueiatus appears as a vertical indenture ; in 2, it is triradiate 

 and the lower limb attempts to join the callosomarginal suleus ; in 4, it is long and deep and 

 incises the margin of the hemisphere (doubtless some anatomists will see in this a typical suit/us 

 precentralis marginalis, but as surely they will concede that the marginal constituent in the pre- 

 central sulcal system is most unstable) ; in 5, the sulcus is again deep and effects a true junction 

 with the callosomarginal sulcus ; in 6, it appears as a mere dimple. 



The interrupted line encloses the area occupied by Betz cells. 



By inlaying strips of cotton wool during fixation the sulci were artificially widened. 



For these drawings I am indebted to Mr F. J. Abrani. 



