234 



K. A. b Ai'Mi; \i;r\i.i; 



A median sagittal section of an adult Sceloporas shows only 

 two parts to the hypophysis; the anterior lobe and the pars 

 intermedia.. The anterior lobe, shorter than in turtles, lies elose 

 against the brain floor (fig. 47). Its anterior end is oval and the 

 caudal end flattened. The pars intermedia has a residual lumen 

 with a thick roof and a thin floor, the latter, continuous below 

 with the anterior lobe (fig. 47). A series of transverse sections 

 of turtles (figs, 9 13) were drawn at varying - distances from the 

 anterior end. The levels at which all transverse sections of 

 reptiles were drawn are shown in table 3. The first drawing of 

 the series of Sceloporus (fig. IS) shows the anterior lobe, the floor 



TABLE 3 



Table showing levels at which the drawings of transverse sections of the. hypophyses 



of various reptiles were taken, using an adult turtle as (he standard 



Adult turtle 



28 mm. turtle 



Adult lizard 



30 mm. alligator 



Adult alligator 



12 cm. snake embryo 

 Adult snake 



DISTANCES FROM THE ANTERIOR EN'D OF THE HYPOPHYSIS 

 OF AN ADULT TURTLE 



0.61 mm. 



Figs. 9 

 Figs, fi 

 Figs. IS 

 Figs. 27 

 Figs. 30 

 Figs. 39 

 Figs. 42 



1.23 mm. 



10 



28 



31 



1 91 mm. 



11 



i 

 19 



32 



2.52 mm. 



12 

 S 



20 



33 

 40 



3.2S mm. 



13 



21 

 29 

 34 

 41 



44 



of the brain and the muscles at either side; figure 19, the infun- 

 dibulum and the anterior end of the pars intermedia. In the 

 next figure the pars intermedia, with its central cavity and the 

 anterior lobe are shown. In the ventral part of the anterior 

 lobe is a cystic tubule (fig, 20). The relations of the cranium 

 to the hypophysis are seen in figure 20. The caudal end of the 

 anterior lobe is entirely surrounded by bone and the two cerebral 

 carotid arteries lie at either side (fig. 21). 



Development in alligators 



In the 12 mm. alligator studied, the four parts of the hypophysis 



described in other reptiles are well formed. The lateral buds 

 are finger-like processes on either side, anterior to Rathke's 



