THE DEVELOPMENT OF THE HEART IN SHAD. 

 H. D. SENIOR. 



Ectoderm, superfic. 



Ectoderm, basal 



Eniodermal ns-c-.__.«s^ 



pharynx, dorsal wall ^^^^^^Eniodermal pharynx 

 3^ ventral wall 



Somltal mesoderm 



Mandibular pouch 



Lateral plate 



Entodermal 

 pharynx, ventral wall 



Fig. 3.— Transverse sections of sliad, stage of 15 somites x 100 diams. 

 For situation of sections see footnote on opposite page. 



The American Journal of Anatomy. — Vol. IX, No. 2. 



