378 



WALTER E. CAMP 



Figure 21 is from a wax reconstruction of the left supra- 

 pericardial body of an embryo 28 mm. in length (H. E. C. 1357, 

 stage 30 of Scammon's Normal-plate). Here the digitiform 

 tubule of the preceding stage has become converted into a 

 single rounded vesicle with a connecting-stalk, which has a 



Oes. 



Fig. 2 Ventral view of a wax reconstruction of the pharynx of an Acanthias 

 embryo 20.6 mm. long (H. E. C. 1494). X 24. The gill-pouches have been cut 

 off close to their origin from the pharynx. M., mouth; R.p., Rathke's pouch; 

 T., thyreoid; / to VI, first to sixth gill-pouches; S.b., left suprapericardial body; 

 Oes., oesophagus. 



broad attachment to the vesicle but is constricted at its connec- 

 tion with the pharyngeal wall. It contains a narrow lumen 

 which communicates above with the pharynx and below with 

 the saccular cavity of the vesicle. The stalk is attached to the 

 caudal portion of the cyst, giving the gland a cranialward directed 

 development which later becomes more 'marked. 



