THE DIENCEPHALIC FLOOR 227 
Fig. 4 Mesial view of forebrain reconstruction in adult fowl (Gallus gallus). 
x 50. The unshaded area shows the cut surfaces of the reconstruction. 2, 
chiasmatic process; 4, chiasm; 1/, infundibular stem; 12, infundibular canal; 
13, infundibular process; 14, infundibular process, saccular surface; 15, infun- 
dibular process, pituitary surface; 16, infundibular process (lateral process) ; 
27, mammillary body; 32, post-chiasmatic eminence; 33, post-chiasmatic recess ; 
34, post-infundibular eminence; 35, post-infundibular recess; 38, pre-chiasmatic 
recess; 40, recess of the infundibular process; 41, supra-optic crest; 42, supra- 
optic recess. 
considerable distance into the ventricular chamber. The hypo- 
thalamic portion of the ventricle extends caudad beneath the 
ventral surface of the massive tuberculum postero-superius; for 
this reason the caudal portion of the post-chiasmatic eminence 
and the post-infundibular eminence appear to be appendages 
to rather than constituents in the floor of the third ventricle of 
the fowl. In the bittern (fig. 5), on the other hand, the post- 
infundibular eminence is in the ventricular floor while the 
