THE DIENCEPHALIC FLOOR 245 
greatly decreased in size and seem to be on the point of 
disappearing. 
The median mammillary and post-mammillary evaginations 
are no longer recognizable, but a protuberance marking the 
position of the corpus interpedunculare (4) is still defined as the 
24 
AQ, weagae et Oe 
Fig. 14 Mesial view of forebrain reconstruction of 70mm. cat embryo. X 26. 
The unshaded area shows the cut surface of the reconstruction. 2, chiasmatic 
process; 4, chiasm; 5, corpus interpedunculare; 13, infundibular 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 infundibular process; 4/, supra-optic crest; 42, supra- 
optic recess. 
thickened area in that part of the floor. The other eminences 
and recesses defined in the earlier stages are all present with but 
slight changes. 
Cat embryo of 70 mm.; Specimen No. E 70 (fig. 14). In its 
main outlines the diencephalic floor at this stage has attained 
its adult ‘conformation. It is not, however, disposed in the 
