THE FISSURA HIPPOCAMPI 129 
terminalis as a limit. There is always some tissue, therefore, 
which retains the initial two layers of the early conditions. The 
area intercalata changes little in morphology. Its extent in- 
creases most noticeably in the dorso-ventral direction. Intrinsic 
differentiation is practically identical throughout the older 
brains of the series (19.1 mm. to 43 mm.). 
Sul.lim. 
Mes. pl. 
i Mes f-pl- 
Soa SS Rec. inf. 
3 Bee fie 
\ 
Rec. op. 
Dienrpl. [\ah. Rec. postop. 
Lam. ep. Ne Fb.op.ch. 
A.ep. \ 2 Rec. preop. 
Alene See = = |y eae Lam.term. 
Undif. fas.den. “Qs. , ee Fil. olf. 
qaltven 7 \- oe Sept. 
Taltenteloneda” Sept. epen. 
Prim. hip. / A.tnt. |4 
Fig. 14 Pen-and-ink outline of the same brain taken from the same point of 
view as that shown in figure 13. The extent of the medial olfactory areas is 
projected upon the medial wall of the telencephalon. The arrows indicate the 
plane of section. 
The lamina epithelialis lying between the lateral limb of the 
paraphyseal arch and the sulcus limitans hippocampi increases 
in relative importance in the older embryos. In the 11.8-mm. 
the amount of epithelial tissue adjoining the lateral limb of the 
paraphyseal arch is more extensive than that adjoining the 
unarched portion of the roof of the telencephalon medium. ‘There 
is no lateral choroid plexus here; neither is the telencephalon 
more than a slight evagination. However, in the 14-mm. embryo 
