

106 BULLETIN OF THE BUREAU OF FISHERIES. 



The third pair of parietal arteries are given off opposite the sixth vertebra and 

 have the same branches as the second, described above, with the addition of a small 

 branch to the swim-bladder. This additional branch (86) arises from the peritoneal 

 blanch of each parietal artery and immediately enters the swim-bladder to supply, 

 with its fellow of the opposite side, the anterior dorsal portion. 



The fourth pair of parietal arteries arise opposite the eighth vertebra and have 

 branches corresponding- to those of the third. The vessel to the swim-bladder, how- 

 ever, is larger than the corresponding branch from the third pair, and supplies the 

 median dorsal portion. 



Between the origin of the fourth and fifth parietal arteries, though but slightly 

 anterior to the latter, the dorsal aorta sends a large branch to the kidneys. This 

 vessel, the posterior renal artery {■>.!). leaving the ventral surface of the aorta, runs 

 caudad and ventrad in the posterior division of the kidney, which it supplies, and 

 sends a branch also to the bladder. A short distance beyond its origin it gives off 

 two vessels, each of which almost immediately divides into a peritoneal branch (85) 

 and a branch (86) which supplies the posterior dorsal surface of the swim-bladder. 



The fifth pair of parietal arteries is given off opposite the tenth vertebra, just 

 caudal to the posterior renal artery, as stated above. Each divides into a dorsal and 

 an intermuscular branch. The peritoneal branch belonging to this segment arises 

 from the posterior renal artery, as already stated. 



The dorsal aorta at this point leaves the abdominal cavity and continues as the 

 caudal aorta, inclosed by the haemal arches of the caudal vertebrae. It gives off, 

 opposite alternate vertebrae, three branches, two lateral, one on each side, and a 

 median ventral branch. Each lateral branch divides almost immediately into an 

 intermuscular (87) and a dorsal artery (88). The ventral branches (93) arise as 

 median vessels from the ventral surface of the caudal aorta. They run ventrad in 

 front of the haemal spines of their respective vertebra? and divide into right (££d) and 

 left (94s) branches which run ventrad, one on each side of the pterygiophores of the 

 anal tin. At the base of the anal tin each one of these branches divides into an 

 anterior and a posterior branch. These anastomose with corresponding vessels, thus 

 fori. ling a continuous artery on each side of the base of the anal fin (95) in the same 

 manner as do the dorsal branches at the base of the dorsal tin. these continuous 

 arteries (95) giving off small branches (•%') to the skin and tin. The first ventral 

 branch of the caudal aorta, which is given off opposite the eleventh vertebra, is 

 somewhat larger than the more caudally situated ventral branches, and its anterior 

 branch extends craniad to supply the muscles around the cloaca. 



The caudal aorta terminates in two branches which run dorsad and ventrad. 

 respectively (97), in a groove at the base of the caudal tin, supplying the latter by 

 means of numerous small branches (98). 



THE VENOUS SYSTEM. 



The veins (tig. 17, pi. i) will be described in the following order: 



I. The hepatic portal system. 



II. The veins opening into the sinus venosus. 



III. The veins opening into the Cuvierian ducts. 



IV. The caudal vein and venae •idvehentes of the kidney. 



