250 Vertebrate Embryology 



formed by the union of the two large vitelline 

 veins, bringing blood back from the vascular 

 area, but also received blood from the anterior 

 end of the body of the embryo through the two 

 anterior cardinal veins, and from the posterior 

 end of the embryo through the posterior car- 

 dinal veins. The anterior and posterior cardi- 

 nals of each side unite with each other, just 

 before emptying into the meatus venosus, to 

 form the short ductus Cuvieri (Fig. 66, dc). 



The anterior and posterior cardinal veins, 

 during the earlier stages of development, bring 

 back the blood to the heart from practically 

 all parts of the body except from the digestive 

 organs. 



The anterior cardinals persist as ihe jugular 

 veins, being joined, at an early period, by the 

 pectoral veins from the anterior appendages, 

 and the vertebral veins from the head and neck. 



So long as the Wolffian bodies remain func- 

 tional, the posterior cardinals retain their large 

 size ; but when the permanent kidneys become 

 functional, these veins diminish in size and 

 ultimately disappear. 



The ducti Cuvieri or Cuvierian veins persist 

 as the anterior vence caves of the adult chick 

 (Fig. 78, V.S.L. and V. S. R.). 



