94 



THE ANATOMY OF VERTEBKATED ANIMALS. 



The umbilical vein further gives a branch to the livei-; 

 while, on the other hand, it commtinicates directly with the 

 venous sinus (now almost merged in the vena cava inferior) 

 by a tmnk called ductus venoms (Fig. 26, Bv.). 



Fig. 26. 



Fig. 26.— Diagram of the arrangement of the principal vessels in a 

 human foetus. H. the lieart ; T.A. the aortic trunk or cardiac 

 aorta; c. the common carotid ; c' the external carotid ; e" the internal 

 carotid ; s. subclavian ; v. vertebral artery ; 1, 2, 3, 4, .5, the aortic 

 arches— the.persiptent /e/i aortic arch is hidden; A.' subvertehral 

 aorta; o.omphalomeseraic artery, going to the umbilical vesicle r, with 

 its vitelline duct dv. ; o, omphalomeseraic vein ; rp, the vena porta? ; 

 X. the liver; ?/w, the hypogastric or umbilical arteries, witli their 

 placental ramifications, «"m''; u' the umbilical vein ; Z)t', the ductus 

 veuosus ; J'/i, the hepatic vein ; cv, the vena cava inferior ; vil, the 

 iliac veins ; az, a vena azygos ; vc', a vena cardinalis posterior ; 

 DC. a dncttis Cuvieri ; the anterior cardinal vein is seen com- 

 mencing in the head and running down to the ductus Cuvieri on the 

 under side of the numbers 1, 2, 3, 4, 5 ; P, the lungs. 



When the umbilical vesicle and allantois cease to have any 

 further import, as at birth, or before, the omphalomeseraic 



