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Fig. 1. Diagrams of the entire vascular system of young Ceratodus. (Outlines 

 after Semon.) A at the time of hatching. B 3 days after hatching. C 63 days 

 after hatching, a. afferent branchial artery, ab. abdominal vein. a.c. anterior carotid 

 artery, a.cd. anterior cardinal vein. ao. primary aortic arch. c. caudal vein. d.ao. dorsal 

 aorta, e. efferent branchial artery, h. hepatic veins, h.m. hyomandibular artery, h.p. 

 hepatic-portal vein. hy. hyoid diverticulum, i.j. inferior jugular vein. i.r. interrenal 

 vein. I. lingual artery. I.e. lateral cutaneous vein. p.c. root of posterior carotid artery. 

 p.cd. posterior cardinal vein. s.i. subintestinal vein. s.j. superior jugular vein. tr. posterior 

 trunk vein. v.c. vena cava. 



