DEVELOPMENT OF THE ELASMOBRANCH LIVER 



367 



bile duct and cystic duct to the right and the left hepatic forward 

 and laterally. This condition is shown by a frontal section of a 

 much older embryo in figure 19. 



D.cyst. 



Vomph. I 



.hep.r 



D.cbol. 



V. mt. 



Fig. 19 Frontal section of lui Acanthias embryo 41 mm. long (H.E.C. 371). 

 X 40. D.chol., ductus choledochus; D.cyst., cystic duct; D.hep.r., right hepatic 

 duct; Int.y.s., internal yolk sac; Pane, pancreas; St., stomach; V.ini., valvular 

 intestine; V.omph.l., left omphalo-mesenteric vein. 



An embrj-o 20.5 mm. in length shows sufficient differentiation 

 of the embryonic hepatic structures to pfermit the introduction 

 of the adult terminology in describing them. As will be seen from 

 a cross section through the anterior end of the gall bladder of a 

 specimen of nearly the same stage (fig. 20), both lateral and me- 

 dian pouches are reduced in diameter and the tubule groups, in 



