[Proc. Roy. Soc. Victoria, 30 (N.S.), Pt. I., 1917j. 

 Art. VI [. — Abnormal Circulation of a Frog. 



By ELLINOR ARCHER, B.Sc. 



(Government Research Scholar). 



(With Plate XVIII). 

 [Read 9th August, 1917J. 



During the usual dissection of the frog (Hyla aurea) by students 

 in tlie Biological laboratory of the University of Melbourne, one 

 of the specimens was found to show a hitherto unnoticed abnormal 

 arrangement of certain vessels of the venous system. 



The organs were well developed and sliowed no trace of being 

 affected by the altered circulation as might have l^een expected, 

 especially in the case of the liver. 



The anterior abdominal vein was the chief vessel showing the- 

 abnormality. It commenced from the two pelvics as a normal-sized 

 vessel; it then, instead of being augmented by the two parietals, as- 

 is normally the case, passed some of its blood into the parietals on 

 the left side, which was an unusually large vessel. The parietal 

 on the right side was normal." 



The anterior abdominal beyond the two parietals was smaller 

 than is usually the case, and was continued up the length of the 

 body to the heart, across the liver and across the ventral surface of 

 the heart, entering the left anterior vena cava at the point at which 

 it is formed by the large anterior veins. 



The hepatic portal opens directly into the liver without being 

 joined by the anterior abdominal vein, which therefore had no- 

 communication Avhatever with the liver. 



The musculo-cutaneous branch of the left subclavian appeared 

 abnormally large, and the branch which enters the muscular body- 

 wall was traced down and found to be a continuation of the large 

 abnormal parietal. This vessel ran between the obliquus externis 

 and obliquus internis muscle of the body wall. Apparently some 

 of the blood via the pelvics and anterior abdominal entered the left 

 parietal and flowed through it to the musculo-cutaneous, and so on 

 into the left anterior vena cava and sinus venosus. 



The abnormal connection of the left parietal and musculo- 

 cutaneous vein may l>e readily explained on the presumption that 

 during the early development the capillaries of these vessels which 



