THE ELASMOBRANCH FISHES 



205 



are connected bj- the interorbital vein which traverses the interorbital canal 

 (see fig-. 47, facing p. 44). The blood thus collected in the orbital sinus passes 

 through the postorbital groove and then backward in the enlarged anterior 

 cardinal sinus over the pharyngeal region. The sinus receives nutrients from 

 the gills. At the level of the most posterior gill arch the anterior cardinal drops 

 down and enters the duct of Cuvier or the postcardinal sinus (Scyllium, fig. 

 190b, a.c.s.). The branches to the anterior cardinal may be considered further. 



Fig. 190. Anterior cardinal system. 

 A.Mustelus. (From T. J. Parker.) B. Scyllium. (From O'Donoghue.) 



a.c.s., anterior cardinal sinus; a.c.v., anterior cardinal vein; a.f.v., anterior facial vein; 

 tr.v., brachial vein; h.s., hyoidean sinus; h.v., hyoidean vein; i.j., inferior jugular; l.a.v., 

 lateral abdominal vein ; l.c.v., lateral cutaneous; n.s., nasal sinus; o.s., orbital sinus; p.c.s., 

 postcardinal sinus; p.c.v., posterior cerebral vein; s.cl.v., subclavian vein; s.sc.v., subscapu- 

 lar vein. 



A supraorbital vein (so.v., fig. 192a) collects blood from the skin and the 

 jelly-like tissue overlying the cranium, and passes forward from the segment 

 of the parietal fossa (p.f.) over the dorsal surface of the nasal capsule. At the 

 place where the superficial ophthalmicus nerve {fo.VII, fig. 192a) perforates 

 the cartilage the left supraorl)ital receives a small dorsomedian rostral vein 

 {dm.v.). 



