226 Transactions.— Zoology. 
walls, several small panereatie veins from the right lobe of the pancreas, 
and a large anterior splenic vein (a. sp. v) from the spleen, as well as the 
intra-intestinal vein mentioned below: the mesenterie receiving transverse 
veins from the intestinal walls, and a large lieno-gastric vein (l. g.v) which is 
formed mainly by a longitudinal vein from the left side of the stomach and 
receives also veins from the spleen. After receiving the lieno-gastrie, the 
mesenteric vein runs through the left lobe of the pancreas, receiving veinlets 
from it, and unites with the duodenal immediately anterior to that gland. 
The common portal vein passes dorsal to the bursa Entiana and along the 
right side of the stomach, parallel with the ccliae artery and bile-duct, 
receiving as it goes the veins for the right side of the stomach. 
In the paper already referred to on the spiral valve of the skate, I 
described that structure as being supplied entirely by the mesenteric arteries 
and veins, but stated that the bursa Entiana received a special blood-supply 
in the duodenal vessels. Owing, however, to imperfect injections, I missed 
one important point. The spiral valve of Elasmobranchs has, in fact, a double 
blood-supply : vessels from the transverse branches of the mesenteric—and 
in Seymnus, Mustelus, ete., of the duodenal—arteries and veins pass inward 
to it, but in addition to these its free edge encloses an artery and vein which 
may be traced forwards into the duodenal artery and veins respectively. The 
vein in question has been shown by Balfour* to be formed from part of the 
sub-intestinal vein of the embryo. As far as I know no name has been 
given to it as it occurs in the adult, and as it corresponds to part only of 
the sub-intestinal vein, and is known to persist only in the spiral valve of 
Cyclostomata and Elasmobranchs, I propose to call it the intra-intestinal vein, 
and the artery accompanying it the intra-intestinal artery. It attains its 
greatest dimensions in those sharks which possess a scroll-valve, such as 
Zygena, Carcharias, and Galeocerdo,} but is almost equally conspicuous, as 
I have lately found, in Mustelus antarcticus and in Callorhynchus antarcticus, 
both of which have an ordinary spiral valve, although that of the Holo- 
cephali shows transitional characters to the scroll-valve.t In Scymnus, as in 
the skate, the intra-intestinal vein is quite small and easily missed in 
injecting. 
But the most interesting point in the vascular system of Scymnus is the 
presence of a large lateral vein, having the same essential relations as the 
vein I described in the skate.§  Posteriorly it is connected with the veins 
from the pelvic fin, from the anterior border of which it passes forwards 
* Comparative Embryology, vol. ii., p. 535. 
t See Duvernoy, Ann. des Sci. Nat., ser. ii., 1835, t. iii. 
1 See “ Spiral Valve of Skate," loc. cit. 
; “On the Venous System of the md eias. N.Z. Inst., vol. xii., pp. 413-18, 
