434 J. B. JOHNSTON 
Fig. 4 A forebrain from which the entire medial wall of the pallium has been 
cut away, seen from the medial direction. The large dorsal ventricular ridge is 
divided into a chief lobe and a basal lobe by a shallow groove. The bifurcation 
of the middle ventricular groove is not wellshown. One branch descends into the 
temporal horn of the ventricle; the other runs for a short distance in the bottom 
of the shallow groove on the dorsal ridge. Compare figure 10. This brain shows 
an unusual prolongation of the basal part of the dorsal ridge into the caudal pole. 
The part of the striatum seen here is the head and tail of the caudate nucleus. 
Figs. 5 to 10 These are photographs of a model of the right half of the fore- 
brain made by the method of plate reconstruction. The method of building up 
and dissecting the model is explained in the text. Before photographing, the 
outer surface of the model was lightly smoothed and then painted in two colors. 
All the olfactory centers including the hippocampus were painted a light yellow- 
green. The somatic structures, striatum and general pallium, were painted 
light blue. In the photographs all the olfactory centers have a dark tone. The 
ventricular surfaces and the cut surfaces have received no treatment whatever. 
The hypothalmie region was not completed. 
Fig. 5 Lateral surface of the model. The dorsal border of the pyriform lobe 
is sharply marked through its whole length. The caudal border is only arbitrarily 
fixed. A broken line marks the limit between the large-celled and small-celled 
parts of the pyriform lobe. The olfactory part of the amygdaloid eminence 
appears depressed owing to its color and to its being in shadow. Compare figure 
8. The structures surrounding the striatal area constitute a continuous ring of 
small-celled olfactory nuclei. 
Fig. 6 Medial view of the model. Thelip of the choroid fissure and the lamina 
terminalis are painted white. The model is cut between the hippocampal com- 
missure and the anterior commissure, so that the commissure may be removed 
with the whole hippocampal formation. A broken line indicates roughly the 
boundary between the hippocampus proper and the subiculum. Probably too 
large an area is included in the subiculum at the anterior end. The somatic 
pallium should have been carried farther forward here in constructing the model. 
Note the oblique position of the peduncular constriction. Note also the fissura 
prima, the fimbrio-dentate sulcus and the moulding of the caudal pole around the 
thalamus and midbrain. 
