480 
The relations of the pronephros to the big blood vessels have 
hitherto not been correctly described. The pronephros is often stated 
to lie (apparently, but not, of course, morphologically, in a large 
venous sinus. JACKSON says that the left anterior cardinal passes 
between the gut and the left pronephros, from which it receives a 
twig, and the “anterior portal vein” (=right anterior cardinal) is 
said to pursue a corresponding course. In my large series of sections 
of Myxine I find the facts are as follows: The left anterior cardinal 
(5) shortly behind the anastomosis (6) divides into two vessels—a 
larger dorsal (5°) and a smaller ventral (5°). The two latter pass 
backwards, and open separately into what may correspond to the left 
Cuvierian duct (14), which itself passes forwards and cannot be 

Fig. 1. Myxine glutinosa. Reconstruction from serial sections of a 25 cm. 
Hag of the venous trunks associated with, and in the neighbourhood of, the heart, 
as seen from the dorsal surface. X 6. The vessels have been somewhat displayed 
laterally for the sake of clearness. 1, Sinus venosus. 2, position of sinu-auricular 
aperture. 3, auricle. 4, ventricle. 5, left anterior cardinal or superior jugular vein. 
5', dorsal division of the left anterior cardinal vein. The circles represent the 
extent of the left pronephros. 5'', ventral division of the left anterior cardinal vein. 
6, anterior cardinal anastomosis. 7, right anterior cardinal, superior jugular, or 
“anterior portal vein”. 7°, dorsal division of the right anterior cardinal vein. The 
circles represent the extent of the right pronepbros. 7‘, portal heart, representing 
the ventral division of the right anterior cardinal vein. 8, portal or supra-intestinal 
vein. 9, common portal vein to liver. It gives off a vessel to the anterior lobe of 
the liver (9'), and the remainder passes to the posterior lobe (9). 10. Inferior 
jugular vein. 1/2, common posterior cardinal vein or azygos vein. 11‘, left and 
11", right posterior cardinal veins. 12, anterior hepatic vein. 13, posterior hepatic 
or sub-intestina] vein. 14, left ductus Cuvieri. 
distinguished from the sinus venosus (1). It is, in fact, doubtful, in 
the absence of developmental evidence, whether a Cuvierian duct can 
be identified in Myxine at all, especially as the hepatic veins open 
into the only venous channel which can be described as such. The 
