152 



ZOOLOGY 



SECT. 



The venous blood is brought back from the head by a pair of 

 jugular or anterior cardinal sinuses (Fig. 830, jug. v.), and from the 

 trunk by a pair of posterior cardinal sinuses (r. and l.card.s.). At 



the level of the 

 sinus venosus the an- 

 terior and posterior 

 cardinals of each side 

 unite to form a short, 

 b?-v 4 nearly transverse sinus, 

 br.t'f the precaval sinus or 

 ductus Cuvieri (Fig. 

 830, dct. c.), which is 

 continued into the 

 lateral extremity of 

 the sinus venosus. In- 

 to the precaval sinus, 

 about its middle, opens 

 an inferior jugular 

 sinus (inf. jug. v.} 

 which brings back the 

 blood from the floor of 

 the mouth and about 

 the branchial region of 

 the ventral surface. 

 The two posterior car- 

 dinal sinuses extend 

 backwards throughout 

 the length of the body- 

 cavity ; in front they 

 are enormously dilated, 

 behind they lie be- 

 tween the kidneys. 

 Anteriorly each re- 

 ceives the correspond- 

 ing subclavian vein 

 bringing the blood 

 from the pectoral fin 

 and adjacent parts of 

 the body-wall. The 

 lateral vein (I. v.), in- 

 stead of joining with 

 the subclavian 

 (p. 91), opens separ- 

 ately into the precaval. 



The genital sinus discharges into the posterior cardinal sinus. 

 There are two portal systems of veins, the renal (r. and l.port.v.) 



and the hepatic portal (hep. port, v.), by which the kidneys and liver, 



r.bort.v 



l.Jborb. v 



ccutd.v 



FIG. 830. Hemiscyllium. Diagrammatic representation of 

 the ventral aorta and afferent branchial arteries, and of the 

 chief veins. aZi. alimentary canal; br.v.i-br.v? afferent 

 branchial arteries ; cau/1. v. caudal vein ; dct. c. precaval 

 sinns ; hi. heart ; h.port. v. hepatic portal vein ; hep. s. 

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

 jug. a. jugular vein or sinus ; Int. v. lateral vein ; liv. liver ; 

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

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

 right renal portal vein. 



