504 J. H. JOHNSTON 



Fig. 23 Section through the rostral wall of the preoptic recess and the nucleus 

 of the diagonal band (gyrus subcallosus). Between the level of figure 22 and this 

 the pyriform lobe has rapidly pushed up over the outer surface of the pallial 

 thickening as described in the text. The dorsal ridge is decreasing in size and 

 the arrangement of its cells in this and in figure 22 suggests the core-nucleus of 

 the adult. The dorsal ridge and the pallial thickening form a common large 

 ridge, while in the adult they are separated by a groove (see '15 b, fig. 10). 



Fig. 24 Section through the rostral end of the dorsal ridge and through the 

 fissura prima, in which the fibers of the diagonal band are turning up into the 

 medial wall. Both pallial thickening and pyriform lobe are massive. 



Figs. 25, 26 and 27 Sections through the anterior part or motor area of the 

 general pallium. The whole of what is called general pallium here becomes more 

 massive in the adult and is included in the pallial thickening. An important 

 feature of these sections is that the general pallium especially at the dorso-medial 

 angle is composed of conspicuously large cells. If the results of experiments re- 

 ported elsewhere in this journal are to be credited, this is certainly a part of the 

 motor area and probably is concerned with the control of the limbs. The pres- 

 ence of the large cells is readily understood if this is true. 



