26 Macteay Memoria VoLume. 
very peculiar anastomosis with the left vena cava superior. This last anastomosis 
is also indicated on the right side; but its arrangement is somewhat different ; 
namely, the right vena cava superior emits a branch inwards towards the aorta, 
running parallel with the arteria coeliaca. The branch is widely open at its origin, 
and colouring matter can easily be injected into its cavity from the vena cava; but 
the canal is gradually obliterated and closed entirely before it reaches the aorta. 
Probably there exists an open communication between the vein named and the aorta 
at an early period of life.” 
The branch in question (fig. 8, ~ vert. v.), which appears to exist only on the 
right side, is formed by the union of several small branches from the side of the 
vertebral column behind the region of the cceliac artery. It crosses the latter and 
then immediately turns downwards by the side of the brachial artery receiving as it 
does so branches from the outer surface of the membrane between the ribs lying just 
behind the latter artery. It then crosses beneath the brachial artery and runs 
downwards, inwards and forwards, increasing rapidly in size till it joins the trunk 
formed by the union of the jugular and subscapular vein in exactly the position in 
which, on the left side, the posterior cardinal joins this. 
We have, I believe, in this vein, the proximal part of which is abnormally large 
in proportion to its area of distribution, the remnant of the anterior part of the right 
posterior cardinal, which now simply serves to carry back blood from the anterior 
vertebral and costal region of the right side. 
G. Brachial veins (figs. 8, 15, and 16). 
The blood from each of the anterior limbs is returned to the heart by a vessel 
which runs superficially from the anterior aspect of the limb upwards in the hinder 
wall of the gill cavity till it falls into the short trunk running between the proximal 
end of the superior and inferior jugular veins. It receives a small branch from the 
dorsal face of the median coracoid portion of the limb girdle. 
H. Cutaneous vein system (figs. 8, 15, and 16). 
In Mustelus amongst Plagiostomes Parker has described the presence of paired 
lateral cutaneous and median dorsal and ventral cutaneous veins. In Ceratodus 
there is no trace of a dorsal cutaneous vein and though in the anterior part of the 
trunk ventrally a vein lies somewhat close to the external surface, this has been 
shown above to be a direct forward prolongation of pelvic veins and hence cannot be 
regarded as equivalent to a cutaneous vein. 
