230 FREDERICK TILNEY 
cat and fowl and at the same time this region is a relatively 
much more expansive area than in the forms already mentioned. 
Two of its divisions are bilaterally symmetrical in the form of 
large ovoid protuberances situated one on either side of a smaller 
median area. The lateral protuberances are the lob inferiores 
(21); they correspond in position to the lateral processes of the 
Fig. 6 Mesial view of brain reconstruction in adult Mustelus laevis. X 25. 
The unshaded area shows the cut surfaces of the reconstruction. 2, chiasmatic 
process; 3, cerebellum; 4, chiasm; 6, diverticular sacci vasculosi; 7, epiphysis; 
10, hypophysial recess; 12, infundibular canal; /4, infundibular process, saccular 
surface; 15, infundibular process, pituitary surface; 20, lamina terminalis; 21/, 
median chiasmatic groove; 24, mid-brain; 26, mammillary recess (recess of pos- 
terior lobe); 27, mammillary body (posterior lobe); 32, post-chiasmatic eminence 
(inferior lobe); 33, post-chiasmatic recess (recess ot inferior lobe); 34, post- 
infundibular eminence; 35, post-infundibular recess; 39, paraphysis; 42, supra- 
optic recess; 44, Sicicephalons 47, velum transversum. 
post-chiasmatic eminence in birds and mammals; they are not 
invested by or in contact with the pituitary gland. The small 
median area corresponds to the median post-chiasmatic groove 
(23); it is contiguous with a relatively long, tongue-like process 
of the pituitary gland, the developmental history of which latter 
