THE HYPOPHYSIS IN REPTILES 241 



the anterior lobe (fig. 67) . The former is wide and somewhat con- 

 cave where the slight infundibular outgrowth lies in contact with 

 it. The anterior lobe is also wide and almost comes into contact 

 with the brain floor in front of the infundibulum. Very small 

 projections at the base of the anterior lobe, more marked on the 

 right side than on the left, are the only remaining evidence of the 

 lateral buds. The wide ventral end of Rathke's pouch somewhat 

 overhangs the small hypophyseal stalk which is attached to the 

 floor of the anterior lobe. The stalk is arched slightly forward. 

 From both surfaces of the anterior lobe there are many small 

 evaginations, not evident in the reconstruction (fig. 67), but 

 shown in the figure of a sagittal section (fig. 37). 



A median sagittal section of a 10 cm. Tropidonotus embryo 

 shows distinct growth of all parts and particularly of the anterior 

 lobe (fig. 38). Most marked, however, is the apparent straight- 

 ening out of the hypophysis and the obliteration of the early 

 acute angle between Rathke's pouch and the anterior bud. The 

 anterior lobe, now elongated cranio-caudally, has a very irregular 

 outer surface, due to the great development of tubules. The 

 solid hypophyseal stalk, extending forward and downward, is 

 attached to the hypophysis near its anterior end and is 

 continuous with the oral roof. The pars intermedia is a large 

 well-developed outgrowth from the superior end of Rathke's 

 pouch. Cau dally it is surrounded by a large venous channel and 

 anteriorly it comes into contact with the tip of the small infun- 

 dibular evagination. The narrow lumen of the pars intermedia 

 is continuous with that of the anterior lobe. The lateral buds 

 have disappeared and there is no evidence of any structure hav- 

 ing developed from them. A thin connective tissue layer joining 

 the tips of the cartilages forming the floor of the chondrocranium, 

 lies in close contact with the ventral surface of the hypophysis. 

 A similar layer appears to anchor the dorsal surface of the anterior 

 lobe to the floor of the brain. 



A series of cross sections of a 12 cm. Eutaenia sirtalis embryo 

 shows the relations of the hypophysis to the brain and the rel- 

 ative sizes of its parts. The first drawing (fig. 39) shows the 

 anterior lobe with its irregular surface lying to the right of the 



JOURNAL OF MORPHOLOGY, VOL. 28, NO. 1 



