CIRCULATORY SYSTEM OF THE GRASS-SNAKE. 633 



The Supra-renal Portal Systera. — Each supra-renal body has 

 a portal supply, an arrangement of vessels which is universally 

 present in snakes according to Beddard (1), who, however, attributes 

 the discovery of this system to Gratiolet in 1853 (17), wdiereas it 

 had been described seven years previously by Ecker (15). The 

 supply consists of two, but in more rare cases of three, intercostal 

 veins which arise from the corresponding side of the dorsal bod}'- 

 wall and also of a vessel from the oviducal sinus in the female, 

 all of these pour their blood into the supra-renal network. The 

 last of these vessels is rather small and runs at the level of the 

 middle of the ovary on each side. 



The Hepatic Portal Vein (Vena portte, Schlemm) arises by two 

 roots, from the renal portal veins, which unite to form a single 

 vessel on the dorsal wall of the rectum in a way that has already 

 been described *. It passes forward through the gut mesentery, 

 receiving on its way numerous branches from the many coils of 

 the small intestine and also from the fat-body. Towards its 

 anterior end a tributary joins it bringing blood from the front 

 pai-t of the intestine, the pancreas, and the spleen. This is shortly 

 followed by another vein coming from the gall-bladder. In the 

 same region it is joined by the anterior abdominal vein which 

 runs down from the fat-body. From this point instead of being 

 on the ventral side of the post-caval vein it passes dorsally to the 

 left of this vessel and enters a furrow on the dorsal side of the 

 liver. Between the entrance of the vein fj'om the pancreas and 

 the spleen and the posterior end of the liver, i. e. just anterior to 

 the superior mesenteric artery, the hepatic portal vein receives 

 three large intei'costal veins from the parietes of the right side. 

 The vessel runs in the groove of the liyer right to its anterior end, 

 gradually diminishing in calibre, and it receives in this part of its 

 course a more or less regular series of intercostal veins arising to 

 the left of the vertebral column and a greater number of small 

 veins from the stomach and oesophagus. A very similar condition 

 obtains in T. fasciaius (Beddard, 1). 



I. The Anterior Abdominal Veinf, correspoi^ding to the simi- 

 larly-named vein in Lacertilia, is a single small vein arising at 



* According to Schlemm (35) the hepatic portal yeiii has onlj' one root, and that 

 arises from the right renal portal vein. This statement is also made in Hoitmanu 

 (23), but it should be noted that this author quotes nearly the whole of Schlemm's 

 account of the venous system almost verbatim without indicating in anj' waj' that 

 he is so doing. My own investigations confirm those of Jourdain (27) and Hoch- 

 stetter (20), who describe a double root for this vein in Trojjidoxotus, one part 

 arising from each renal portal vein. The latter author makes a similar statement 

 with regard to Coluber cssculapii. Beddard (4 & 3) has also recorded the same 

 arrangement in Coluber corais, Zamenis gemon,enSf,s, and Ancistrodon piscivoriis. 

 According to Jaquart (26) there are a number of anastomoses between the hepatic 

 portal vein and the right renal portal vein in Fijthoii. In Gadow's account of 

 Pelophilus madaga$carietisis, quotei by Hoffmann (23), it is stated that there is no 

 connection between the hepatic portal and renal portal veins. 



t This vein is especially interesting, as it is subject to considerable variation among 

 the Ophidia. In Lizards, as is well known, it arises by two roots from the renal 

 portal veins, and a similar condition is to be found in some snakes, viz., Ert/.v jacithis, 

 JE.jolini, Pi/tJion sehce, and Uoa diviiiiloqita, Beddard (2,3, & 4). In other snakes 



Proc. Zool. Soc— 1912, No. XLII, 42 



