CELL MASSES IN THE FOREBRAIN 453 
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Fig. 39 Transverse section through the upper end of the gyrus subcallosus, 
showing the dense nucleus of the diagonal band close to the recessus superior. 
From the same section as figure19. The position of the hippocampal commissure 
shows that this nucleus pushes up near the medial surface above the level of the 
commissure. This is shown in the model, but the ventral border of the hippo- 
campal primordium in front of the commissure curves dorsally still more than is 
shown in the model (fig. 6). Note how much smaller these cells are than those 
of the adjacent hippocampal primordium. Indeed these are among the smallest 
cells in the forebrain. Magnification 110 diameters. 
