262 FREDERICK TILNEY 
entiation of the post-chiasmatic eminence still further and . 
makes it possible to recognize more clearly in the two lateral 
processes of this eminence the anlages of the lobi inferiores. The 
median post-chiasmatic groove remains as a narrow strip of the 
brain floor in which the tissue is relatively thin, while the inferior 
lobes are becoming massive, thick-walled bodies. The recess 
33 32 
Fig. 28 Mesial view of forebrain reconstruction of 70 mm. Mustelus. X 50. 
The unshaded area shows the cut surfaces of the reconstruction. 2, chiasmatic 
process; 4, chiasm; 7, epiphysis; 18, infundibular evagination; 26, mammillary 
recess; 27, mammillary body (posterior lobe); 32, post-chiasmatic eminence 
(inferior lobe); 33, post-chiasmatic recess (recess of inferior lobe); 35, post- 
infundibular recess; 36, post-infundibular eminence; 39, paraphysis; 40, recess 
of infundibular process; 41, supra-optic crest; 42, supra-optic recess; 44, 
telencephalon. 
of the ventricle in relation with the region of the median groove 
extends laterad upon both sides into the inferior lobes. The 
chiasmatic process (2) has increased in size and consequently 
projects further into the ventricle, thus accentuating the bounda- 
ries of the prechiasmatic and post-chiasmatic recesses. The 
former recess may be traced laterad into a small canal which 
overlies the optic chiasm and the proximal portion of the optic 
