168 MARION HINES 
remainder of the group described the angulus terminalis separates 
the midline structures into terminal plate and roof. The former 
is the lamina terminalis; the latter, the area chorioidea. The 
lamina terminalis increases in length and width throughout the 
series. The area chorioidea changes little in total length. Its 
anterior division, the tela chorioidea telencephali medii, is practi- 
cally stationary. Its posterior division, the paraphyseal arch, 
in the younger embryos forms a tent-like evagination in the 
roof; in older stages it may become a pouch-like paraphysis 
with two lateral pockets. 
6. The portion of the medial wall of the hemisphere con- 
tiguous with the area chorioidea and the dorsal thin part (pars 
tenuis) of the lamina terminalis is termed the area epithelialis. 
It may be divided into the following parts, enumerated from 
ventral to dorsal borders: 
1) The septum ependymale (fig. 14, Sept. epen.) is that portion 
of the area epithelialis which lies ventrally of the angulus ter- 
minalis and borders the dorsal thin portion of the lamina ter- 
minalis. In later stages it thickens, beginning at the ventral 
border, differentiating first into matrix and marginal velum, with 
later migration of neuroblasts of the septal nuclei into the latter. 
The dorsal portion remains thin and undifferentiated. 
2) The area intercalata (figs. 14, 16, A. ini.) lies contiguous 
to the tela chorioidea telencephali medii. It remains membra- 
nous and increases but slightly in total surface and thickness. 
3) The lamina epithelialis (figs. 14, 16, Lam. ep.) borders the 
paraphyseal arch and becomes transformed into the lamina 
epithelialis of the lateral choroid plexus of the adult. Its an- 
terior moiety subtends the paraphyseal arch and the invagina- 
tion of the choroid fissure begins between the 14-mm. and the 
16-mm. stages. Its posterior moiety contiguous to the di- 
telencephalic fold of the velum transversum thereafter rapidly 
expands. 
7. The neopallium grows more rapidly than any other part 
of the telencephalon. Its initial differentiation follows that of 
the hippocampus; its subsequent development surpasses that of 
the latter. The identification of the future hippocampus in the 
