XII VASCULAR SYSTEM 323 
vein, as already mentioned (Fig. 190), but more or fewer of them, 
especially those from the dorsal wall of the organ, open into the 
posterior cardinals. They may, as in Polypterus, even join the 
hepatic veins.’ 
The veins from the gonads are very variable in their destina- 
tion, sometimes joining the posterior cardinals, as m the Salmon 
(Salmo salar); or the hepatic portal vein, as in Amiurus ; or, as 
in the Perch (Perca fluviatilis), forming by their union a single 
trunk, which communicates directly with the left Cuvierian 
duct. 
Representatives of the great lateral veins of Elasmobranchs 
appear to be absent in the Teleostomi, the veins from the 
pectoral and pelvic limbs joining the Cuvierian duct and the 
posterior cardinal veins respectively. 
The two large anterior cardinal veins, which collect the blood 
from the head and brain, occupy their usual position directly 
above the branchial apparatus, and are sometimes connected by 
transverse anastomoses as they pass backwards to join the 
Cuvierian ducts. The inferior jugular vein is either single (e.g. 
Gadus); or paired, as in Perca (Fig. 190). 
In the Dipnoi the venous system is distinguished by an 
interesting combination of characters, some of which are either 
primitive or peculiar to the group, while others exhibit a distinct 
transition to the embryonic or the adult condition of the lower 
air-breathing Vertebrates. 
In Neoceratodus ” (Fig. 191) the renal portal system is unusually 
complex, the veins distributing venous blood to the kidneys being 
derived from several sources, as follows: (1) from each of the 
two branches into which the caudal vein divides on its exit from 
the haemal canal (af.7.v); (2) from a common trunk (pé.v) which, 
on each side, is formed by the union of segmental veins from 
certain of the post-cloacal myotomes and is united with its fellow 
by a transverse anastomosis; (3) from more anteriorly situated 
intercostal or segmental veins (i.c.v) which enter each kidney 
directly ; and (4) from a vein on each side corresponding to the 
renal portal vein of Amphibia. The latter vein (7p.v) is formed 
by one of the two branches of the iliac or femoral vein, and joins 
1 Budgett, Trans. Zool. Soc. xiv. Pt. vii. 1901, p. 382. 
2 Giinther, Phil. Trans, 161, 1872, p. 535; Baldwin Spencer, Macleay Memorial 
Volume, 1894, p. 17. 
