438 J. B. JOHNSTON 
Fig. 9 Lateral view of the model with the pyriform lobe removed. At both 
its rostral and caudal ends the pyriform lobe forms the whole thickness of the wall 
over small areas, so that the ventricle is opened in this photograph. Through 
the greater part of its length the pyriform lobe overlies the thickened lateral 
border of the pallium and the dorsal ventricular ridge. A broken line marks 
the boundary between the pallium and this ridge. Along this line a cell-free zone 
separates the pallium from the ridge but the two can not be dissected apart 
owing to the continuity of their cell masses in the region of the amygdaloid fissure. 
The thickening of the lateral border of the pallium which causes the bulging out 
of the pyriform lobe near its rostral end is clearly seen in this photograph. 
