Charles F. W. McClure 21: 
i f 
up its connection with the abdominal portion, continues to function in 
the pouch young as a revehent vein of the liver, and I am inclined to 
believe that it is also retained in the adult (‘Text Hig. 27) as the hepatic 
vein (revehent) which opens into the postcava in common with or in 
close proximity to the large left hepatic vein (see Text Fig. V, Part I, 
which represents a corrosion of the hepatic veins of the adult). 
The arrangement of the umbilical veins in the 6 mm. embryo of Dasy- 
urus is essentially the same as that described above for the 8 mm. em- 
bryos of Didelphys; the only exceptions being that the two in Dasyurus 
are of about the same size and that their continuation within the liver 
opens into the postcava independently of the*left hepatic vein (Text 
Fig. 9, and Figs. 29 and 30, Plate IT). 
So far as known to the writer, Broom, 98, is the only investigator who 
has hitherto described the umbilical veins of the marsupials and, al- 
though his description is somewhat fragmentary, it conclusively shows, 
when compared with the above observations of the writer, that the plan 
of the umbilical circulation in marsupials not only differs from that in 
the higher mammals, but that there is also a difference even among the 
marsupials themselves. 
Broom states that in an 8.5 mm. embryo of Trichosurus a single mod- 
erate-sized vein brings back the blood from the allantois and on reaching 
the umbilicus opens into a rather large sinus which lies round the margin 
of the umbilicus. From the umbilical sinus two large umbilical veins 
pass up to the liver on either side of the large umbilicus. The vein of 
the left side opens into the liver at a point which corresponds to that at 
which the left umbilical opens in the higher mammals; the right um- 
bilical vein opens into the liver on the right side of the quadrate lobe 
and differs from the left in receiving a number of tributaries from the 
abdominal walls. 
Regarding the course of the umbilical veins within the liver, Broom 
states as follows: “ Each vein, on entering the liver through a small 
opening in its wall, falls into a comparatively large venous space. The 
tracing of the veins in the liver at this stage is a matter of considerable 
difficulty; but there is little doubt that each intra-hepatic venous sac 
gives off a small branch inwards and slightly downwards to the portal 
vein, and divides above into a large number of branches, which spread 
over the periphery of the upper part of the liver, and then pass inwards 
to fall into the inferior vena cava.” 
Broom further states that “In a 10.5 mm. Trichosurus embryo the 
umbilical sinus, though very much reduced, can still be detected. The 
development of the sides of the abdominal wall has brought both the 
