XIII 



PHYLUM CHORDATA 



157 



inf.ju-g.v 



which brings back the blood from the tail, running, along with the 

 caudal artery through the inferior arches of the vertebra, divides 

 on entering the ab- 

 dominal cavity into 

 right and left renal 

 portal veins, which 

 end in a number of 

 afferent renal veins 

 supplying the kid- 

 neys. 



The hepatic portal 

 vein (h. port, v.) is 

 formed by the con- 

 fluence of veins de- 

 rived from the 

 intestine, stomach, 

 pancreas, and spleen, 

 and runs forwards to 

 enter the liver a 

 little to the right of 

 the middle line. 1 " In 

 Hemiscyllium a large 

 branch connects the 

 genital sinus with 

 the intestinal tribu- 

 taries of the hepatic 

 portal system. The 

 blood from the liver 

 enters the sinus ven- 

 osus by two hepatic 

 sinuses placed close 

 together. 

 Nervous System. 



The fore-brain con- 

 sists of a rounded, 

 smooth prosence- 

 phalon (Fig. 821, 



V.H.) divided into 



two lateral parts by 



a very shallow median 



longitudinal groove. 



From its antero- 



lateral region each 



half gives off a thick 



cord, which dilates 



into a large mass of nerve-matter, the olfactory bulb (L. ol.\ closely 



applied to the posterior surface of the corresponding olfactory 



\porb.v 



FKJ. 8-20. Hemiscy Ilium. Diagrammatic representation of 

 the ventral aorta and afferent branchial arteries, and of the 

 chief veins, ali. alimentary canal ; br. v.i-br. v.& afferent 

 branchial arteries ; caud. v. caudal vein ; dct. c. ductus 

 Cuvieri ; Id. heart ; hep. port. r. hepatic portal vein ; hep. s. 

 hepatic sinus ; inf. jug. r. inferior jugular vein or sinus ; 

 jug. v. jugular vein or sinus ; lat. v. lateral vein ; liv. liver ; 

 1. card, x left cardinal sinus ; I. port. v. left renal portal vein ; 

 neph. kidney ; r. card. s. right cardinal sinus ; r. port. v. 

 right renal portal vein. 



