No. 462.] LATERAL VEIN OF SKATE. 361 
passed around the narrow posterior end of the rectal extension 
of the cardinal sinus, was tightened so that further flow of the 
fluid into the cardinal sinus was prevented. A very light pres- 
sure on the syringe was maintained, with the result that the 
blue fluid appeared in the posterior region of the mesenteric vein 
and in its posterior branches, whence it passed forward, filling 
most of the veins on the intestine. The intestinal arteries were 
then injected, via the anterior mesenteric artery, with a fluid 
similar to that used for the veins, but colored with pulverized 
carmine. There was no interference or mingling of the blue 
and red fluids on the intestine, nor was there any evidence that 
the blue fluid had passed through capillaries into arteries. 
The injection of the Prussian blue fluid backward into the 
mesenteric vein gave similar proof of the continuity of the portal 
veins and the rectal network. The fluid appeared in extremely 
fine vessels over the entire intestinal wall and, passing through 
the rectal network, entered the cardinal sinus and both lateral 
veins. 5 
To summarize, in Raza erinacea and R. /evis (see the dia- 
gram, Fig. 5):— 
(1) There are no veins similar to the large ilio-haemorrhoidal 
veins described by Parker for R. nasuta. 
(2) The two lateral veins have a common origin in a close 
network of fine vessels distributed over the walls of the rectum 
and cloaca. 
(3) This venous network communicates with the cardinal 
sinus by means of small vessels lying along the ventral margin 
of the mesorectum, in the region of its attachment to the rectal 
gland. 
(4) The vessels of the rectal network communicate with the 
posterior factors of the hepatic portal system as stated by 
Hochstetter and as thought probable by Parker. : 
(5) The lateral vein receives the blood from the pelvic fin, 
there being, in addition to the chief femoral vein, one or two 
smaller vessels from the fin which open into the lateral vein 
independently. 
The relations of the lateral veins to other parts of the venous 
System are, therefore, substantially as described by Hochstetter 
* 
