600 MK, F. E. BEDDARD ON THE ANATOMY OF [May 26, 



seems to lend support to the view that existing mammals have 

 radiated oiit separately in many directions from a common stem, 

 and that no two groups are very markedly nearer to each other 

 than any others. 



This view is in accord with certain opinions expressed by 

 Prof. Osborn. The relative positions of the various groups 

 (excluding those of which I have not sufficient knowledge derived 

 from memoirs or from my own observations) can be expressed in 

 some such diagram (p. 599) as that which accompanies these 

 remarks. The stages referred to are described on a previous page. 



lY. Note on the Existence of a Suprarenal Portal 

 Syste'm in Marsupials. 



Although it is possibly true that physiologically there is no 

 renal portal or supiarenal portal system *, it is plain that among 

 Reptiles, as contrasted with Mammals, there are veins entering the 

 kidneys and the suprarenal bodies from the parietes and hind 

 limbs forming afferent veins to those glands, and thus contrasting 

 with efferent veins which convey the blood from the glands in 

 question directly to the postcaval system. Whether the capillaries 

 intervening between the afferent and efferent veins are real 

 capillaries or sinusoids does not affect the anatomical facts just 

 stated, though naturally of great embryological and physiological 

 importance. Neither does my own suggestion t that the supra- 

 renal portal system is really due to the disappearance of that 

 section of the postcardinal vein which runs over oi- near to that 

 organ on each side and the consequent opening of its (the post- 

 car.dinal vein's) affluents into the substance of the gland. It is 

 still a fact that among Reptiles the suprarenal organs send a vein 

 or veins to the postcaval and receive a vein or veins from the 

 adjacent parietes. And this feature, whatever may be its physio- 

 logical importance or want of importance, is an anatomical feature 

 in which the lower Vertebrata differ from the Mammalia. 



This being the case, attention is directed to the accompanying 

 drawing (text-fig. 124, B) which represents the veins in the 

 immediate neighbourhood of the kidneys of an example of the 

 Marsupial Dasyiorvs maugcei. It will be seen that the suprarenal 

 body of the left side of the body lies anteriorly to the left renal 

 vein and not in contact with it. The vein from this body opens 

 directly into the postcaval vein between the points of entrance 

 thereinto of the two renal veins, but nearest to the left renal 

 vein. In addition, however, to this vein connected with the supra- 

 renal body, another vein is depicted in the figure which arises by 

 more than one veinlet from the adjacent muscles. This vein runs 

 in a direction parallel to that of the postcaval and ends in the 

 suprarenal body, which it enters at the end remote from that 

 whence the suprarenal affluent of the postcaval emerges from the 



* Cf. Woodland, P. Z. S. 1906, p. 886. f P. Z. S. 1906, p. 24. 



