481 
“venous sinus” in which the pronephros is apparently enclosed is the 
dorsal of the two vessels described above, and in the figure the extent 
of the pronephros is represented by the circles. On the right side 
the anterior cardinal or “anterior portal vein” (7) does not terminate 
after opening into the portal heart (7“), but is continued backwards 
as a vessel (7°) which corresponds in every respect with the dorsal 
of the two vessels of the other side, and, like it, encloses the pro- 
nephros of its side. Behind the pronephric region this vessel con- 
siderably diminishes in size, and finally discharges into the portal vein. 
In position and relations the portal heart (7) is the equivalent of the 
ventral vessel of the other side (5“). It will be noticed that the left 
pronephros is more extensive than the right. Without a knowledge 
of the development of these vessels it is idle to speculate on their 
homologies. Even if the general relations of the parts have been 
conditioned by the absence or loss of the right Cuvierian duct, we 
are still without an adequate reason for the extraordinary connection 
between the portal vein and the right anterior cardinal. In the higher 
Mammals the absence of the right Cuvierian duct may be linked with 
the reduction of the right posterior cardinal. In Myxine the right 
posterior cardinal, though much smaller than the left, persists through- 
out life, and we can hardly seek, in the minor loss of its anterior 
section, a satisfactory explanation of the major phenomena which make 
unique the cardiac vessels of Myxine. 
The connection with the liver of the sub-intestinal or posterior 
hepatic vein (13) seems to be of minor importance. The main trunk 
of the vessel is usually superficial in position, it remains fairly con- 
stant in size, and in front has an independent opening into the sinus 
venosus. No factors of the hepatic duct are associated with its 
branches in the liver. It is neither dissolved nor constituted in the 
liver. On the other hand, the posterior lobe of the liver has another 
and a true hepatic vein, constituted within the liver tissue, and corre- 
sponding precisely to the anterior hepatic vein (12). (It is ventral to 
the other vessels, and is not shown in the text figure.) Notwith- 
standing this, the subintestinal vein, as established by injections and 
serial sections, acts both as an afferent and an efferent vessel to the 
posterior lobe of the liver. It has, however, no connection with the 
anterior lobe as figured by Goopricw. These results are partly 
opposed to the statements of Jackson as regards Bdellostoma. He 
says: “It is interesting to note that in Bdellostoma the sub-intestinal 
Anat. Anz. Bd, 46. Aufsätze. 31 
