The Development of the Heart in Shad. 



213 



position of Fig. 21 

 position of Fig. 20 I 

 position of Fig. 19 

 position of Fig 18 



Otocys 



Spinal cord 

 — Ectoderm 



-Notochord 



Br. cleft 2 

 Branchial cleft 3" 

 Branchial a 4 

 Branchial a. 3 

 Ventral aorta 



Dorsal parietal pericardium 

 Conus arteriosus 

 Ainum 



Dorsal aorta 

 Peritoneal coelom 



L. cardinal v. 



CEsophagus 



R. cardinal v. 

 Supravitelline sinus 

 L. jugular v. 



Anterior wall of sinus venosus 



Ventral parietal pericardium 



(mostly removed) 



Fig. 1. — The left side of a reconstruction from the posterior gill region of 

 a recently hatched shad, stage of 114 hours x 100 diams. 



Sufficient body-wall has been removed to open the pericardial coelom 

 ventrally and laterally and to show the terminations of the left jugular 

 and cardinal veins. The anterior pole of the yolk and the adjacent parts 

 of the heart and pericardium are shown in mid-sagittal section. 



