A STRANGE ABNORMALITY IN THE CIRCULA- 
TORY SYSTEM OF THE COMMON RABBIT 
(LEPUS SYLVATICUS. — 
JAMES ROLLIN SLONAKER. 
IN the March number of the Naturalist an article appeared 
“On the Frequency of Abnormalities in Connection with the 
Postcaval Vein and its Tributaries in the Domestic Cat (Felis 
domestica). Such variations are quite familiar to those who 
have charge of laboratory work in vertebrate anatomy. The 
abnormalities are, however, by no means confined to the region 
indicated in the above article. They are common to other parts 
of the circulatory system. 
Though the author does not discuss the probable causes of 
these abnormalities, he suggests that they may be due in part 
to “domestication, in breeding, disease, drugs, and shock.” 
I have found that abnormalities in the circulatory system are 
hot confined to the domesticated cat, but are also of frequent 
occurrence in the common gray rabbit. 
The most noticeable variation that I have found, and the only 
one which I shall describe, was found in the venous system of 
the rabbit. I have found it but once and, as I have seen 
no mention of such an occurrence in the literature pertaining 
to this subject, I will describe it. 
In injecting the posterior vena cava from the heart I was 
amazed by the rapid filling of the portal veins. This continued 
until they were as well injected as the other veins of the body. 
The injecting fluid used was a starch mass which was too 
Coarse to pass from the vena cava through the capillaries of 
the liver into the portal vein. The inference was that there 
was a vein of sufficient size forming a direct connection between 
the portal vein and the posterior vena cava. 
Careful dissection showed this supposition to be true. A 
small vein extended from the posterior mesenteric and united 
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