BLOOD-VASCULAR SYSTEM OF THE LORICATI 73 



specimens where there was no anterior gall-bladder artery, as 

 is shown in iig. 33, there is a fiostcrior oall-bladdcr artery 

 (fig. 33 ; P.G.Bl.A.) arising from the intestinal arter^'^,), which 

 in addition to supplying the gall-bladder is continued caudad to 

 supply a portion of the ileum. The splenic artery (PL IV, fig. 

 31 ; Spl.A.) penetrates the spleen with the splenic vein, but 

 before entering it, gives off 2. posterior gastric artery (PI. IV, 

 fig. 31 ; P. Gas. A.), which passes beneath the spleen to the 

 ventro-posterior end of the stomach ; and like the posterior 

 gastric artery of Ophiodon, which, however, has a different 

 origin, coming from the right pyloric cseca arter}^ it sends off 

 a branch to the posterior portion of the intestine. 



7. Dorsal Aorta. 



This vessel (PI. I, figs, i, 5, and 10 D.Ao.), which is the 

 largest artery in a fish, arises as the most dorsal trunk from 

 the common chamber (PI. I, fig. 5 ; C.C.) and continues 

 caudad in a median line directly below the vertebral column 

 to the last caudal vertebra. At first the dorsal aorta runs 

 between the 2 anterior lobes of the kidney, above and be- 

 tween the dorsal branchial retractor muscles, and when the 

 posterior unpaired part of the kidney is reached, runs along in 

 its dorsal groove. After leaving the kidney and the body 

 cavity, the aorta is known as the caudal artery (PI. I, figs, i, 

 7, 8, 9 and 10 ; Cau.A.). It penetrates the hasmal canal of the 

 first caudal vertebra with the caudal vein and continues in the 

 hsemal canal above the vein until the last caudal vertebra is 

 reached, where at about the middle of the last centrum it 

 separates into a right and a left caudal artery. The le/t cau- 

 dal artery (PI. I, fig. 8; L. Cau.A.) is much the shorter; 

 it sends a branch upward in front of the urostyle, which sup- 

 plies both profundus and superficial muscles. The much 

 larger right caudal artery (PI. I, figs, i and 8; R. Cau.A.) 

 following along the outer margin of the last centrum and after 

 giving off a branch in front of the urostyle similar to the left 

 caudal artery, continues caudad in a median line between the 2 

 hypural bones, parallel with the longitudinal haemal lymphatic 

 vessel, giving off branches from both sides to the profundus 



