THE HYPOPHYSIS IN REPTILES 225 



to the original outpouching is distinctly evaginated and slightly 

 constricted from the oral roof, forming the anterior bud (fig. 

 2). The lumina of the median and lateral lobes are continuous 

 with the larger cavity of the anterior bud, the wall of which is 

 thicker than that of the earlier outpouching. The oral roof is 

 slightly raised at the region of the hypophysis, indicating the 

 beginning of a stalk. 



The lateral lobes are shorter and thicker in the 5.5 mm. 

 Chrysemys than in the 5.2 mm. Aromochelys, and more promi- 

 nent in the 6.5 mm. Chrysemys than in the 6.2 mm. Aromochelys. 

 The anterior bud, in the 6.5 mm. Chrysemys, is not distinctly 

 evaginated. These may be individual variations. 



The hypophysis is well separated from the oral epithelium by 

 a stalk in older embryos. In a 7.2 mm. embryo, a short stalk 

 with a small lumen extends from the ventral wall, near the caudal 

 end of the hypophysis, slightly backward and downward, to the 

 pharyngeal vault (fig. 61). The anterior lobe is very short. 

 The dilated lateral lobes open by means of slightly constricted 

 necks into the caudal end of the anterior lobe. Their free ends 

 extend anteriorly beyond Rathke's pouch. Two small solid out- 

 growths from the caudal wall of the median lobe are present. 

 The dorsal one is similar in position to the projection in younger 

 embryos, with which the notochord came in contact. The ven- 

 tral bud, also solid, lies just above and cranial to the small trans- 

 verse anastomosis of the carotids. The apex of Rathke's pouch 

 is crowded between the spheno-occipital cartilage and the cranial 

 wall. The lower lateral walls of the lateral lobes are indented 

 by the carotids. 



Marked changes have taken place in slightly larger embryos. 

 In an 8.5 mm. embryo the stalk, containing a small lumen, is 

 long and tube-like. One of the solid outgrowths on the caudal 

 surface of the hypophysis is more prominent. Above this the 

 tip of the notochord lies close against the hypophyseal wall. 

 The wide free apex of Rathke's pouch is closely applied to the 

 inf undibulum and shows evidence of beginning glandular develop- 

 ment. Its center is constricted, and the attached end enlarged 

 dorso-ventrally. The anterior lobe is also enlarged. The lateral 



JOURNAL OP MORPHOLOGY, VOL. 28, NO. 1 



