490 FISHES. 



pair of anterior innominate arteries, which supply the anterior 

 gill and the hyoid half gill on each side. 



The purified blood passes from each half gill by an 

 efferent branchial artery. To begin with, there are nine 

 of these on each side, but by union they are reduced to 

 three efferent trunks, which combine to form the dorsal 

 aorta. 



From the efferent branchial of the hyoid arch, a carotid 

 arises, which divides into internal and external branches 

 supplying the brain and head. From the first of the 

 efferent trunks, a vertebral arises which supplies the brain 

 and spinal cord. 



The dorsal aorta gives off — (i) a subclavian to each 

 pectoral fin ; (2) a coeliac to the stomach, duodenum, and 

 liver ; (3) a superior mesenteric to the intestine, pancreas, 

 and spleen ; (4) spermatic arteries to the reproductive 

 organs ; (5) an inferior mesenteric to the rectum ; (6) renal 

 arteries to the kidneys; (7) arteries to the pelvic fins. It 

 ends in the caudal artery. 



At each end of the bow-shaped sinus venosus, there is 

 a pre-caval sinus. This receives venous blood as follows : — 

 (a) from the head by a jugular vein ; (h) from the liver 

 by a hepatic sinus, which runs from one pre-caval sinus 

 to the other like the string of the bow ; (c) from a large 

 posterior cardinal sinus (between the reproductive organs) 

 by a cardinal vein on each side ; (d) from the hind-fin 

 by an epigastric, with which brachials from the fore-limb 

 unite anteriorly. The great cardinal sinus receives blood 

 from the hind limbs, the kidneys, and other posterior parts. 



Blood passes into the liver (a) from the cceliac artery, and 

 {b) by portal veins from the intestine (the hepatic portal 

 system) ; blood leaves the liver by hepatic veins which enter 

 the hepatic sinus. 



Blood passes into the kidneys {a) from the renal arteries, 

 and {b) by renal portal veins from the caudal, pelvic, and 

 lumbar regions (the renal portal system) ; blood leaves the 

 kidneys by posterior cardinal veins, which enter the cardinal 

 sinus. 



Into the pre-caval sinus there also opens the lymphatic 

 trunk, with nutritive fluid from the intestine. 



The heart lies in a pericardial cavity, which is connected 



