567 



ear-like appendages. A marked constriction, the canalis auri- 

 cularis, separates it from the ventricular portion. This latter, 

 RV, is shaped something like the adult stomach, and lies almost 



AP A. 



VD 



A.4 



LQ 



A. 3 



TN 



El 



BM 



IN 



VV 



CO 



YK 



KD 



CH 



KC 



FIG. 243. Human Embryo, lettered by Professor His, Bl, and estimated as 

 twenty-three days old. The brain and spinal cord are exposed from the 

 right side ; and the body is dissected to show the heart, the blood-vessels, 

 and the alimentary canal. (B^rom His.) x 20. 



sec 

 AP 

 CH 

 LG 



TN 



YK, yolk-stalk 



directly across the body ; its right-hand or distal end bends 

 sharply forwards, and passes into the truncus arteriosus, RT, 

 which is attached to the floor of the fore-gut rather further back 



