THE HYPOPHYSIS IN REPTILES 233 



lies along the posterior surface of Rathke's pouch and extends 

 between the diencephalon and mesencephalon. The carotids 

 are crowded between the lateral cartilages and the lateral lobes. 



In a 15 mm. embryo the hypophysis is only slightly larger. 

 The two important changes are the increase in length of the 

 anterior lobe, which has grown dorsalward almost as far as 

 Rathke's pouch (fig. 17), and the lack of development of the 

 lateral lobes. Rathke's pouch, lying below the infundibular 

 outgrowth, has an expanded upper free end and a constricted 

 neck connecting it to the enlarged lower portion of the anterior 

 lobe. The small lateral lobes open into the anterior lobe in front 

 of the opening of Rathke's pouch (fig. 65). The anterior carti- 

 lages have the same position as in earlier embryos. On either 

 side of the upper part of the hypophysis are two masses of 

 striated muscle; the carotids lie along the lateral sides of the 

 lateral lobes. 



The hypophysis of a 17.5 mm. (total length) Lacerta muralis 

 is not as well-developed as the 15 mm. Lacerta agilis just de- 

 scribed. The lateral buds are relatively larger and open into 

 the anterior bud on either side of the constricted attachment of 

 Rathke's pouch. Venous channels separate them from Rathke's 

 pouch and join by an anastomosing branch in front of the latter. 



The lateral buds in a 28 mm. Lacerta muralis (H. E. C. 809) 

 are in contact with the brain floor on either side of Rathke's 

 pouch. Their connections with the anterior lobe are smaller 

 than in the specimen described above. The tip of Rathke's 

 pouch is somewhat expanded laterally. The anterior bud has 

 many glandular outgrowths and a small lumen continuous with 

 that of Rathke's pouch. 



In a 37 mm. Lacerta viridis (H. E. C. 604), two epithelial 

 masses lie imbedded in the wall of the brain. Ventro-medially 

 they extend towards the anterior lobe, but are not in contact 

 with it. The wide anterior lobe, now with many glandular out- 

 growths extending cranialward, is continuous caudally and dor- 

 sally with the flattened tip of Rathke's pouch. The lumen of 

 the latter is flat and extends a short distance into the anterior 

 lobe. 



