218 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



wall. It runs along the ventral surface of the body wall to the 

 bladder, where it, together with its fellow from the opposite side, 

 gives off three branches to that organ. One of these branches 

 sends a short twig to the posterior part of the intestine. The 

 vesical then proceeds to the cloaca, Vs. Gl., fig. 3, PL 10, where 

 it breaks up. At about the center of the vesical artery two 

 branches are given off; one, Vs. I., fig. 3, PL 10, passes cephalad 

 to the muscles on the ventral surface of the ilium, the other runs 

 caudad to the cloaca. Vs. an., fig, 3, PL 10. > 



Just posterior to the anal gland the aorta enters the haemal 

 arches of the candal vertebrae and continues to their end as the 

 Caudal Aokta, Ca. A., PL 9, giving off branches to the muscles 

 of the tail. At the anal gland the aorta gives off two branches, 

 one, GL, PL 9, on each side to the anal gland, and one, M., PL 9, 

 to the muscles of the body wall. 



THE VEINS. 



The venous system of Necturus is exceedingly interesting, 

 showing as it does points of resemblance to that of the Dipnoi 

 on the one hand, and the higher Amphibia on the other. I 

 would call special attention to the sinus between the postcaval 

 vein and the Sinus Venosus; the communication between the 

 posterior cardinals and the postcaval; the anastomosis between 

 the posterior cardinals and the renal portal, — a condition which, 

 it seems to me, is intermediate between that of Protopterus an- 

 nectens and Salamandra maculosa. The constant presence of 

 the anastomoses between the two sets of gastric veins is also quite 

 conspicuous. 



For convenience the venous system will be described under 

 three heads: 



1. EENAL PORTAL. 



2. HEPATIC PORTAL. 



3. SYSTEMIC VEINS. 



In each case the description will be begim with the distal ves- 

 sels and followed towards the heart. 



