188 THE AMERICAN NATURALIST. (VoL. XXXIV. 
(b) PERSISTENT POSTERIOR CARDINAL VEINS.  Lrrr Cov- 
MON ILIAc VEIN (V. iliaca communis sinistra) PRESENT. 
Abnormalities of this type have been described as occurring 
in man, by Cruveilhier, von Gruber, Kollmann,! Lobstein, Nic- 
olai, Quain, Wilde, and others. 
Kollmann, with whom the writer is fully in accord, states as 
follows regarding the significance of this type of abnormality : 
* The significance of this condition can, according to my inter- 
pretation, only be as follows: Persistence of both cardinal 
veins, together with the connecting branch (Verbindungsast)." 
By the * Connecting branch" is meant the vessel which is 
subsequently developed between the veins of the left hind 
extremity and the right posterior cardi- 
nal vein, in correlation with the appear- 
ance of the functional kidneys and the 
. atrophy of the distal portion of the left 
posterior cardinal vein. -This vessel 
becomes the left common iliac vein (7. 
iliaca communis sinistra). 
No instance was met with by the 
writer in which the * Connecting 
branch" ran in the reverse direction, 
that is, between the veins of the right 
Tute. Worreferencetongm. Mnd extremity and the left posterior 
"— "€ cardinal vein. Abnormalities of this 
type, however, have been described by Timmermann, Walter? 
Walsham, and others, as occurring in man. 
Two cases were met with by the writer in which the poste- 
rior cardinal veins were persistent, together with the ** Connect- 
ing branch." 
In one (Fig. 3) the union of the two posterior cardinals (17) 
with the common postcava (1) was opposite the third lumbar 
vertebra; in the other (Fig. 4) this union was opposite the mid- 
dle of the sixth lumbar vertebra. 
In the first-mentioned case, represented by Fig. 3, where the 
1 Kollmann gives a a complete bibliography relating to this type of abnor- 
mality in Bd. viii of the Azat. Anz., p. 113. 
2 See Kollmann’s primi 
