355 



Nachdruck verboten. 



The Persistence of Posterior Cardinal Veins in tlie Frog 



together with 



Some Remarks on the Significance of the Kenal Portal System. 



By Chas. H. O'Donoghue, B. Sc, F. Z. S. 

 Assistant to the Jodrell Professor of Zoology, University College, London. 



With 5 Figures. 

 Part I. 

 The persistence of posterior cardinal veins in thefrog. 

 Two of the specimens dealt with in this note were discovered 

 during class- work dissection in this college, and were apparently normal 

 specimens of adult male frogs (Rana temporaria). The third, for 

 which I have to thank Professor J, P. Hill, was a typical young male 

 specimen of the Australian frog (Liranodynastes peronii). The ab- 

 normalities which revealed themselves in the course of dissection in 

 each case consist in the persistence of the posterior cardinal vein or 

 veins, and the absence of all but the inter-renal segment of the post- 

 caval. It may be taken for granted in the following descriptions that, 

 unless the contrary is stated, the arrangement of the vessels was 

 otherwise normal. 



Description of specimens. 

 Specimen A. S Rana temporaria (Fig. 1). 

 In this specimen, the left posterior cardinal vein is persistent as 

 a large trunk of much the same calibre as the post-caval of the normal 

 frog which runs from the union of the femoral and sciatic veins for- 

 ward alongside the outer edge of the kidney and then upwards to 

 join the innominate. In the anterior part of its course along the 

 kidney, it receives a factor from the very asymmetrical inter -renal 

 vein which runs obliquely across the ventral surface of that organ, and 

 which conveyed the whole of the blood collected by the inter-renal 

 vein into the left posterior cardinal. The persistent posterior cardinal 

 is closely attached to the lateral border of the kidney, but venae re- 

 nales advehentes were apparently completely absent, as was also the 



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