LEPl DOS IREN PARADOX A. 
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Left Posterior Cardinal Vein and Posterior Vena 
Cava. — The left posterior cardinal vein and the posterior 
vena cava (right posterior cardinal) appear on the dorso-inesial 
surfaces of the posterior part of the left and right kidneys 
respectively ; they communicate tlirough these oi’gaiis by an 
intricate meshwork of venous capillaries with the left and 
right renal portal veins (Text-hg. 3, 1. P. Card. andP. F. C.). 
The left posterior cardiual vein, on leaving the kidney, 
passes forwards between the intestine and the body-wall ven- 
trally to the left lung, and passing along the left of the roof 
of the sinus venosus, joins the posterior termination of the 
left anterior cardinal vein to form the left duct of Cuvier 
(Text-fig. 3, 1. D. C.). 
The posterior vena cava (right posterior cardinal vein) 
passes forwards from the right kidney, and inclining some- 
what to the middle line, is embedded in the dorsal surface of 
the liver; here it receives a number of venous radicles from 
the liver substance. Immediately on emergingfrom the ante- 
rior end of the liver it enters the sinus venosus (Text-fig. 3, 
P. F. G.), In the one adult injected Lepidosiren in which this 
part was dissected, there was only one large transverse anasto- 
mosis towards the posterior part of the liver, between the left 
posterior cardinal vein and that part of its fellow on the right 
side that forms the hind part of the posterior vena cava (13). 
Hyrtl mentions four such anastomoses in an adult specimen. 
The renal portal veins posteriorly and the left posteiior 
cardinal and posterior vena cava anteriorly receive veins from 
the body-walls and also vertebral veins. These are segmen- 
tally arranged. 
Right Posterior Cardinal Vein. — The anterior 
portion of the right posterior cardinal vein (Text-fig. 3, r. P. 
Card.) is present as a short vessel near the posterior end of 
the heart ; it receives a vein from the region of the vertebral 
column and one from the body-wall, and the trunk so formed 
joins the posterior part of the right anterior cardinal vein to 
form the right duct of Cuvier. A small vertebral vessel joins 
the left posterior cardinal vein also in this region. 
