RC 



FIG. 57. SURFACE VIEW OF AN EMBRYO OF 52 HOURS. (After 

 Duval.) 



A am, vitelline artery. C, heart. FO, olfactory pit. LC, lateral limits of 

 body. A'C, tail, f 2 , mid-brain. I'va and Vvp^ anterior and posterior branches 

 of the vitelline vein. ^'0, eye. 



'75 



