38 



normal manner by the union of the two pelvic veins, does not enter into 

 the hepatic-portal vein, which is quite normal dividing into two branches 

 one supplying each lobe of the liver, nor is it connected in any way with 

 the liver itself. Instead of so doing it runs forward along the outside 

 of the pericardium and opens into the left sub-clavian vein just at the 

 point where this unites with the innominate and the external jugular 

 veins to form the left pre-caval. 



Somewhat similar abnormalities of the anterior abdominal vein 

 have been recorded by Woodland(3) and Buller(l). The former 

 described a case very similar to the one recorded here; the animal was 

 an adult male frog and the anterior abdominal vein, opening into the 

 left sub-clavian had no connection with the hepatic-portal vein or the 

 liver. In the instance recorded by the latter however, the animal was 

 an adult female , in which the anterior abdominal vein opened into the 

 right sub-clavian vein, and also gave off a very slender branch to the 

 liver. Both these writers have called attention to the fact that this ab- 

 normal condition recalls that which obtains in Ceratoihis in which the 

 anterior abdominal vein opens into the right Ductus cuvieri. 



These abnormalities appear to be readily explicable in the light of 

 the development of the anterior abdominal vein in the frog as described 

 by Marshall (2). This author states that there are at first a pair of 

 these veins running backwards from the sinus venosus and communicating 

 with the veins of the hind leg. Somewhat later the two anterior ab- 

 dominal veins unite at their hinder ends in front of the bladder and 

 then the one on the right side disappears leaving only the one on the 

 left. Still later this remaining vein acquires a secondary connection 

 with the hepatic-jDortal vein and looses its connection with the sinus 

 venosus. 



The explanation of these particular cases appears to be that the 



secondary connection with the hepatic-portal vein has either not been 



acquired or else it has never replaced the original connection with the 



sinus venosus. BuUers specimen would appear to suggest also that in 



this case it was the right anterior abdominal vein that persisted and not 



the left. 



Literature. 



1) Bull er, Journ. Anat. and Physiol. \ol. XXX. N.S. 1896. 



2] Marshall, Vertebrate Embryology. London 1893. 



3] Woodland. Zoologischer Anzeiger. Bd. XXXV. 1910. 



