Chap. V.] 



VJ.SSELS OF EMBRYO. 



207 



a paired system of 

 cardinal veins, 



of which the ante- 

 rior pair collect 

 the blood from the 

 head, and the pos- 

 terior from the 

 body generally 

 (Fig. 90; vc and 

 HC). As these lie 

 at the sides of the 

 body the blood can 

 only pass to the 

 heart by a trans- 

 verse vessel, the 

 diictus Cuvieri 

 (D). These two 

 pairs of anterior 

 and posterior car- 

 dinal veins are 

 possessed by fishes, 

 and the anterior 

 pair remains 

 throughout the 



AA, Abdominal aorta; r.A. 

 HA, right and left roots of 

 the aorta, connected by 

 the collecting vessels (ss') 

 witli the branchial ves- 

 sels Ab ; cc', carotids ; S&, 

 subclavian artery ; KI/, 

 gill clefts ; si, sinus ve- 

 nsus : A, atrium ; v, ven- 

 tricle ; B, bulbus arterio- 

 sus ; vm, omphalo-mesen- 

 ter'c veins ; Ara.oniphalo- 

 niesenteric arteries; ic 

 ic, common iliac arteries; 

 EK, external iliac arteries, 

 A/?,allantoic arteries ; Acd, 

 cnudnl artery ; vc, HC, an- 

 terior and posterior cardi- 

 nal veins; sb', subclavian 

 vein ; D, dnctus fuvieri. 

 (After Wiedersheim.) 



Fie. 90. -Diagram to explain the Arrange- 

 ment of the Embryonic vascular System. 



