No. 462] ABNORMAL VEINS IN NECTURUS. 395 
posteriad. By careful dissection it was separated to a point 
opposite the posterior extremity of the liver. Here it was unin- 
tentionally severed from the postcava at what is believed to 
have been its point of entrance, as it could not be traced any 
farther. Its junction with the postcava could not be determined 
positively on account of its small size, the injury to the delicate 
wall of the postcava, and the exudation of the injected starch 
mass. The identity of this vessel is open to question, but from 
its relations and course, and by analogy with the somewhat 
similar cases mentioned above, it was most probably the atro- 
phied left posterior cardinal corresponding to the very much 
hypertrophied right posterior cardinal, which was functioning as 
the anterior part of the postcava. 
No further abnormalities were observed in either the circu- 
latory or other systems. ; 
Comparing this case with the normal venous system and con- 
sidering the development of the postcava, it is inferred that the 
right hepatic vein (or at least the anterior part of tt) represents 
the anterior part of the normal postcava, the normal “ Mittel- 
stück” of the postcava having failed to develop. Wiedersheim 
('98, p. 371), speaking of the development of the postcava in 
Amphibia, says: * Der vordere (Leber) Abschnitt entstammt 
offenbar zum Theil der rechten V. omphalo-mesenterica, zum 
Theil aber entsteht er unabhängig.”  Hochstetter (88) states 
concerning the development of the postcava in Salamandra : 
*Das Wesentliche an der Hohlvenenbildung ist demnach die 
Verbindung zwischen Lebervenen und Cardinalvenen und die 
Verschmelzung der Cardinalvenen in ihrem Urnierenabschnitte " 
(p.105); ,... "due Verschmelzung erfolgt übrigens erst ziem- 
lich spát,.nachdem der sich ganz selbständig entwickelnde 
Abschnitt der vorderen Hohlvene sich mit der rechten Cardi- 
nalvene in Verbindung gesetzt hr "(p 103), Aus 
nahmsweise kommt es manchmal vor, dass die Entwicklung 
eines vorderen Hohlvenenabschnittes vollständig ausbleibt, dann 
bildet sich entweder die rechte oder linke Cardinalvene weiter 
aus und führt im erwachsenen Thiere das Blut der Nieren, 
Geschlechtsorgane und des Rumpfes dem Herzen zu” (p. 164).' 
In comparison with the abnormal cases previously described, 
