1909. | POSTCAVAL VEIN IN MAMMALS. 501 
or both cardinal collaterals*) and its connection with a vein of 
the body-wall. 
On the left side two vessels run, one on each side of the ureter 
to the renal vein of that side into which they opened after fusing 
into one vein. Lower down, these vessels were connected by 
several cross-anastomoses. The outer of the two, which is the 
real anterior ovarian vein, anastomoses with the posterior ovarian 
vein only just in front of the ovary. The inner and more slender 
of the two vessels could be distinctly seen to pass dorsally of the 
posterior ovarian, and to follow the ureter to the bladder. On 
the right side the outer (ovarian) vessel did not fuse with the 
posterior ovarian, but passed dorsally to it. I did not follow the 
more slender vessel beyond the posterior ovarian. Between the 
left renal vein and the posterior bifurcation of the postcaval were 
four stout intercostal veins, of which two lay above the entry of 
the right ovarian, which enters the postcaval in common with 
the third of these four veins. The lumbar parietal veins flow 
into the common iliac vein on either side. The ovarian arteries 
escape from the aorta just at the bifurcation of the postcaval, as 
shown in text-figure 132, p. 499. 
In Pseudochirus peregrinus the veins in question are much like 
those of Trichosurus vulpecula, but show differences of detail. 
The renals are but slightly asymmetrical. Into each renal opens 
a vein at right angles, which is compounded of two running along 
the ureters. These become separate ata very short distance from 
the renal vein. ‘They appear to cross the spermatic vein without 
forming an anastomosis with it, and they do not anastomose with 
each other. The spermatic veins are symmetrically paired and 
flow into a postcava some way below the renals. There are two 
intercostal veins lying between the influx of the spermatics and 
the left (lower) renal. On one side of the body I noted an 
anterior lumbar parietal vein, which passes along the lower border 
of the kidney at right angles to the anterior spermatic vein, 
from which it arises close to the renal vein. The posterior lumbar 
parietal veins flow perhaps rather into the iliacs than directly 
into the postcaval stem, but are just at the junction of the 
two. 
In Onychogale lunata both anterior and posterior spermatics 
were present, though I am uncertain as to an anastomosis 
between them. The posterior spermatics were very asymmetrical, 
the left being much above the right. The latter, indeed, joined 
the postcaval only just in front of the bifurcation to form the 
iliac veins. The renals were also as usual asymmetrical. 
In Onychogale frenata the typical Marsupial arrangement was 
met with in all its essentials. There were nevertheless slight 
differences in detail between these two Marsupials. The renal 
veins although asymmetrical were not very much so, the right- 
* Tt is impossible to fix accurately, without embryological data, which part of 
the postrenal section of the postcaval is here dealt with. 
