70G 
PROFESSOR T. J. PARKER ON THE 
formed from the pre-caudal portion of the sub-intestinal vein or primitive ventral 
vascular trunk of the embryo. It is usually stated, for instance by Miller (17), 
Stannius (25), and Milne Edwards (14), to be absent in those genera in which a 
true spiral valve is present, but has been shown by myself (22) to exist as a large and 
conspicuous trunk both in the species now under consideration and in Callorhynchus 
cintarcticus. 
The intra-intestinal vein of Mustelus (Plate 36, figs. 12 and 13 ; Plate 37, figs. 22 
and 30, Lit. intest. V .) is a large vessel, fully 8 mm. in diameter at its anterior end 
when moderately distended with injection. It lies imbedded in the free edge of the 
spiral valve, having therefore itself a spiral twist, and is accompanied by the intra- 
intestinal artery. It receives veinlets from the inner or central portions of the 
various turns of the spiral valve, emerges through the wall of the intestine (fig. 12) 
immediately dorsad of the pylorus, receiving as it does so a small duodenal vein 
( Duod. V.) from the dorsal wall of the duodenum, and finally joins the ventral 
intestinal and posterior lieno-gastric veins about 2-3 cm. to the right, and dorsad of 
the pylorus. 
The ventral intestinal vein. 
Duodenal vein (in Raja and Scymnus ), Parker (20-23). 
This, the second large vein of the intestine (Plate 36, figs. 12 and 13 ; Plate 37, 
figs. 22, 30, Vent, intest. V.), accompanies the artery of the same name, receiving 
transverse feeders from the walls of the gut, and from the outer or peripheral portions 
of the successive turns of the spiral valve. In the greater part of its course it is 
double, the two divisions lying one on each side of the artery. Anteriorly it passes 
to the left, between the intestine and the narrow pyloric division of the stomach, and 
finally turns immediately cauda.d of the pylorus to join the intra-intestinal and 
posterior lieno-gastric veins. 
The 'posterior lieno-gastric vein. 
This (Plate 36, figs. 12 and 13, Post. li. gast. V .) is a moderate-sized vessel lying 
between the pyloric division of the stomach and the adjacent right lobe of the spleen, 
and receiving feeders from both. Anteriorly it passes dorsad of the pylorus to join 
with the two preceding vessels as already described. 
The gastro-intestinal vein 
(Plate 36, figs. 12 and 13, Gast. intest. V .) is a large vessel lying parallel to and 
dorsad of the main portal vein, and joining the latter about 6 cm. cephalad of the 
pylorus. Posteriorly it is constituted by the confluence of the dorsal intestinal 
