PHYLUM CHORDATA 



157 



irf.Juff.v 



r.card.s — 



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

 caudal artery through the inferior arches of the vertebrae, divides 

 on entering the ab- 

 dominal cavity into 

 right and left nnal 

 portal veins, which 

 end in a number of 

 afferent renal veins 

 supplying the kid- 

 neys. 



The hepatic portal 

 vein (A. 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. 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 hull {L. oL), closely 

 applied to the posterior surface of the corresponding olfactory 



bort.v 



CCUU)L.V 



[r;. 820. — Hemiscyllium. Diagrammatic representation of 

 the ventral .aorta and afferent branchial arteries, and of the 

 ehief veins, ali. alimentary canal ; hr. v^-hv. v.^ afferent 

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

 Cuvieri ; ht. heart ; he'p. port. >'. hepatic portal vein ; hep. 8. 

 hepatic sinus ; -m/. juij. v. inferior jugular vein or sinus ; 

 lug. V. jugular vein or sinus ; lat. v. lateral vein ; liv. liver ; 

 /. card, s left cardinal sinus ; I. port. v. left renal portal vein ; 

 7ieph. kidney ; r. card. 8. right cardinal sinus ; r. port. v. 

 right renal portal vein. 



