ABNOEMAL VEINS IN THE FEOG. By Thomas W. Shore, 

 M.D., B.Sc. (Lond.), Lecturer on Comparative Anatomy and 

 Biology to St Bartholomevj s Hospital and College. 



A FEW months ago I described ^ an unusual arrangement of the 

 veins of the common frog, in which the left renal portal vein, 

 instead of ending in the capillaries of the kidney, passed onwards 

 as a large vessel forwards round the anterior border of the 

 kidney, to open directly into the post-caval vein. Since then I 

 have been on the look-out for abnormalities in the veins of this 

 animal, and, during the past year, four interesting variations 

 from the usual arrangement have turned up in the animals used 

 in the ordinary practical classes in my laboratory. 



1. An Unusual Renal Portal Vein. — The first specimen, which 

 I now describe, was somewhat similar to that described and 

 figured in this Journal, vol. xiv., N.S., p. 398. It afi'ected the 

 left renal portal vein, which, instead of breaking up into capil- 

 laries in the kidney, passed straight through the substance of 

 this organ as a large vessel with undiminished calibre directly 

 into the post-caval vein. It did not lie deeply in the kidney, 

 but was quite superficial and completely visible on the ventral 

 surface of the organ without dissection into it. As it emerged 

 from the inner border of the kidney, it took the place of the 

 second of the renal veins which are usually present, and then 

 contributed a very considerable part of the post-caval. A good 

 idea of the condition present is afforded by the accompanying 

 figure. 



The explanation of this abnormality is, I think, the same as 

 that I put forward to explain the abnormal renal portal vein 

 previously described — viz., that the renal portal represents some 

 portion of the embryonic posterior cardinal, with which, in 

 development, the subsequently formed post-caval becomes con- 



^ This Journal, vol. xiv., N.S., i). 398. 



