THE HYPOPHYSIS IN REPTILES 249 



the hypophyseal end. In lizards it is still present, although 

 very small in 28 mm. embryos. In both of these animals the 

 caudal side of the stalk is convex. Gaupp stated that while the 

 stalk is present in a 47 mm. Anguis fragilis, it has disappeared 

 in the 60 mm. stage. Melcher ('99) found that the stalk dis- 

 appeared at about the 21 mm. stage in Gecko and Gisi ('07) 

 in 20 mm. SphenQdon, although she found a strand of connective 

 tissue indicating the position of the stalk in 28 mm. embryos. 

 Bruni ('13) described a remnant of the stalk in an adult Gongylus 

 and Staderini ('05) a foramen in the cranium for the remnant of 

 a stalk also in an adult. In young snake embryos the stalk is 

 convex caudally as in turtles and lizards. In a 10 mm. embryo 

 it arches forward at the hypophyseal end and has disappeared 

 in 12 cm. embryos. 



Reese ('10) stated that the hypophyseal stalk had degenerated 

 in its middle part in a 6 cm. alligator embryo, and that only a 

 small part at the hypophyseal end remained in a 13 cm. embryo. 

 In the 12 cm. embryo here described, the entire stalk is present 

 (fig. 26). It is long and S-shaped as described by Reese, arching 

 caudalward and ventralward from the hypophysis and extend- 

 ing in the direction opposite to that found in snakes. 



Lizards have a small mass of epithelium projecting dorso- 

 caudally from the stalk where it is attached to the oral roof. 

 The close relationship between this mass (Seessel's pouch) and 

 the hypophyseal stalk, found only in this group of reptiles, has 

 apparently not been observed by other investigators studying 

 Lacerta agilis. It is similar to that observed by Bruni ('13) in 

 chick. Gaupp ('93) figured Seessel's pouch further caudalward 

 in a 27 mm. Lacerta. 



In figures 1 to 5 of young turtle embryos, there is a relative 

 caudalward migration of the attachment of the stalk to the 

 hypophysis, 'while in alligators (figs. 22-26) and snakes (figs. 

 35-38) the attachment remains near the anterior end of the 

 hypophysis. In an alligator embryo 12 cm. long, however, 

 the attachment is more caudal than in younger ones. This 

 may be due to the growth of the hypophysis cranialward, or to 

 the interference of the developing cranial floor. That there is 



