228 FREDERICK TILNEY 
infundibular process projects caudad as an appendage of the 
postchiasmatic eminence. Both the optic chiasm (4) and the 
chiasmatic process (2) in the fowl are prominent and the pre- 
chiasmatic recess (38) is correspondingly deep. In its general 
features the post-chiasmatic eminence (32) is similar to that in the 
cat. It has a long transverse axis. Its ventral surface presents a 
longitudinal furrow, the long axis of which is in the median line. 
4 
Fig.5 Sagittal section of Botaurus lentiginosus in region of interbrain. 
4, chiasm; 11, infundibular stem; 12, infundibular canal; 14, infundibular proc- 
ess, saccular surface; 15, infundibular process, pituitary surface; 26, mammil- 
lary recess; 27, mammillary body; 34, post-infundibular eminence; 35, post- 
infundibular recess; 40, recess of infundibular process; 42, supra-optic recess. 
This is the median post-chiasmatic groove. Here the neural 
tissue is relatively thin. Extending laterad in both directions 
from this groove the surface of the eminence becomes convex 
while the neural tissue rapidly increases in thickness until it 
forms the prominent lateral processes (21) of the post-chiasmatic 
eminence which project free of the diencephalic floor. The 
general plane of the post-chiasmatic recess (33) is at right angles 
to the interthalamic portion of the ventricle and follows the 
ectal contour of the post-chiasmatic eminence. The infundib- 
ular canal (12) is short and narrow; it communicates directly 
with the recess of the infundibular process (40). The latter 
presents dorsally a number of minute tubular canals which 
