The development of the urinogeuital organs of the lamprey, 47 



ends blindly. It is very thin-walled and contains many fibrous septa 

 that appear to divide it more or less completely into two at the 

 cephalic end. Sometimes it is found full of blood and sometimes not. 

 Besides the connection with the intestinal vein there are many openings 

 into the cardinals at irregular intervals and all the blood of the gonads 

 and kidneys is poured into it. Fine injections were made from dif- 

 ferent parts of the sinus cephalad and caudad and also through the 

 portal vein. The result showed that the flow of liquid is more ready 

 caudad and any such injection does not fill the cardinals posterior to 

 the mesenteric vein, the flow apparently being concentrated into the 

 intestinal vein. There is no cephalic connection between the sinus 

 and the cardinals or auricle, the sinus terminating blindly. That this 



is a blood-vessel is beyond question" etc "This sinus is then 



evidently a means of introducing into the portal system a large amount 

 of venous blood that comes from urogenital and body veins. This 

 makes the lampreys possessors of a connection between the genital 

 and portal veins and gives them one more feature in common with 

 the very dissimilar members of this class, the Myxinoids." It would 

 appear from the foregoing observations of Bert and Miss A. Clay- 

 pole that while the blood moves forward to the heart in the posterior 

 cardinal veins, it must move backwards in the subcardinal sinus and 

 enter the intestine to find its way ultimately into the portal vein 

 which is enclosed in the spiral valve and pours the blood into the 

 liver. Notwithstanding this arrangement, some of the blood from 

 the intestine would seem to find its way into the cardinal veins through 

 the small mesenteric vein which I find in front of the vein from the 

 subcardinal sinus. 



Rathke and Schneider and more recently Goette (1891) have 

 studied the vessels of the intestine, the first in Ammocoetes, the second 

 in Ammocoetes and Petromyzon^ the last in the embryo. Goette 

 describes the development of a vein running forward on the ventral 

 side of the intestine, the subintestinal vein. It had been seen and 

 described by Rathke and Schneider in Ammocoetes where it functions 

 as the portal vein. It atrophies, however, during metamorphosis and 

 its function is assumed by a vein which is formed at this time and 

 accompanies the intestinal artery in the spiral valve of the gut. 

 Goette has shown that these two vessels, the subintestinal of the 

 larva and the definitive portal vein of the adult, though confounded 

 b'y some authors, really arise on opposite sides of the intestine, the 



