THE HYPOPHYSIS IN REPTILES 227 



a small lumen, and apparently is the remains of the upper end 

 of the hypophyseal stalk. The definitive anterior lobe is com- 

 posed of the early anterior bud and the anterior end of Rathke's 

 pouch. The anterior lobe is circular, with an irregular surface, 

 due to the cell cords projecting out in various directions. 



The lateral lobes have grown decidedly forward and dorsal- 

 ward. Their distal ends are flattened, presenting a wing-like 

 form, and extend forward against the brain floor. The proximal 

 parts, crescentic in cross section, lie lateral to the anterior lobe, 

 and are attached to its ventro-lateral wall (fig. 62). A lumen is 

 no longer present in the lateral buds. 



The apical enlargement of Rathke's pouch, now the pars inter- 

 media, is widened greatly in a 20 mm. Aromochelys embryo 

 (fig. 5). Many cords extend laterally under the branching in- 

 fundibular outpouching. The pars intermedia is continuous ven- 

 trally with the anterior lobe. 



The anterior lobe in a 28 mm. embryo has a star shaped 

 appearance in transsection, the arms being sometimes enlarged. 

 This and the lateral lobes lie near the brain floor (fig. 6). The 

 proximal parts approach each other, encircling the middle region 

 of the anterior lobe (fig. 7). The pars intermedia has also 

 elongated. A transverse section (fig. 8) shows cord-like out- 

 growths and a narrow connection with the anterior lobe. Its 

 close relation to the overlying infundibulum is also shown. 



In young adult Chrysemys marginata, the hypophysis has 

 elongated, measuring 0.5 mm. or more by sections. Its caudal 

 end lies between two thin lamellae of bone, the lower one form- 

 ing the roof of the mouth. An anastomosing branch joining the 

 two cerebral carotids, lies partially imbedded in the caudal end 

 of the hypophysis. The carotids lie close to the lateral sides, 

 in the angle between the infundibulum and the main part of the 

 pituitary body. A loose connective tissue surrounds the hy- 

 pophysis, while laterally and in front are some of the eye mus- 

 cles. The oval anterior lobe lies close against the brain floor. 

 The distal portions of the lateral lobes are now continuous across 

 the median line, and form a crescent-shaped lamella applied to 

 the brain floor, and extending beyond the anterior lobe. Ven- 



