THE HYPOPHYSIS IN REPTILES 251 



the chorda and stated that the latter degenerates or is trans- 

 formed into other tissue. 



In young turtle embryos the tip of the notochord frequently 

 comes into contact with a small tubular projection from the 

 caudal surface of the hypophysis near the hypophyseal stalk. 

 Up to the 9.4 mm. stage the notochord ends close to the hy- 

 pophysis. Later the two are separated, either by a cranial- 

 ward growth of the hypophysis or by degeneration of the ante- 

 rior end of the chorda. 



In lizard embryos 3 mm. in length the hypophyseal angle is 

 distinctly caudal and ventral, but close to the tip of the noto- 

 chord. In 5 mm. embryos the tip of Rathke's pouch is anterior 

 to the tip of the chorda and approximately on the same hori- 

 zontal plane. In embryos 15 mm. in length the chorda is still 

 close to the hypophysis, so that the notochord and surrounding- 

 cartilages sometimes cause a depression in the caudal hypophyseal 

 surface. Later the hypophysis is more dorsal and in the same 

 transverse plane. 



The anterior end of the chorda in an alligator 12 mm. long is 

 nearer the dorsal part of Rathke's pouch than it is in other rep- 

 tiles. Later, this part of the pouch, having grown distinctly 

 dorsalward, projects anterior to the tip of the chorda. The 

 notochord ends directly dorsal to the anastomosing branch of 

 the carotids. In a 28 mm. embryo it is still close to the hy- 

 pophysis, though relatively further ventral. In young alliga- 

 tors, as in turtles, the notochord and its surrounding cartilages 

 depress the caudal surface of the hypophysis. The anterior 

 bud, at first ventral and slightly caudal to the end of the chorda 

 is later anterior to it and in about the same horizontal plane, 

 (figs. 22-26). There is then, in alligators as in pig (Woerdemann 

 '13), a ventral migration of the end of the chorda in its relation 

 to the hypophysis. 



In snake embryos the anterior end of the chorda degenerates 

 very early and it is difficult to trace its anterior portion. In 

 one specimen it showed attachment to Seessel's pouch. 



In Aromochelys, Chrysemys, Lacerta and alligator, the noto- 

 chord may come into contact with the hypophysis, but in none 



