THE FISSURA HIPPOCAMPI 139 
Figs. 26 to 28 Photographs of three transverse sections through the 14-mm. 
embryo, no. 940. Two views of a model of this brain are shown in figures 10, 
12, 13, and 14 and planes of sections are illustrated in figure 12. 
Fig. 26 Section just anterior to the lamina terminalis and the tela chorioidea 
telencephali medii. The division of the medial wall into three regions is evi- 
dent, namely, 1) a dorsal or neopallial; 2) a dorso-medial or hippocampal; 3) a 
ventral or septal. 
Fig.27 Through the paraphysis. In comparing this with figure 24 of no. 1121, 
the same upward curve in the membranous roof and the division of the dorsal 
half of the hemisphere vesicle into four regions may be noted. X 60. 
Fig.28 Through the di-telencephalic groove. Note the thin marginal velum 
bordering the limitans meningea on the dorsal aspect of the evagination in the 
primordial hippocampus. The massive undifferentiated area joining the dien- 
cephalon medially is the telencephalic limb of the di-telencephalic groove caudal 
to the choroid plexus evagination. 
