CIRCULATORY SYSTEM OF THE GRASS-SNAKE. 625 



7. The Anterior Left Renal Artery divides soon after its origin 

 into two branches, one going to the fat-body and the other to 

 the kidney. This latter brtmch supplies the anterior half of the 

 kidney and sends a twig to the oviduct. 



8. The Second Inferior Mesenteric Artery arises about the level 

 of the anterior end of the left kidney, and supplies the intestine 

 in the region of the median part of the right kidney. 



9. The Median Right Renal Artery, in addition to taking blood 

 to the posterior median part of the kidney, sends a branch to the 

 right oviduct. 



10. The Posterior Right Renal Artery feeds the posterior end of 

 the kidney and gives off two branches to the oviduct. 



11. The Third Inferior Mesenteric Artery, arising near the level 

 of the posterior end of the right kidney, supplies the intestine in 

 the region of the posterior part of the left kidney. 



12. The Median Left Renal Artery is distributed very similarly 

 to the coi'responding vessel on the right. 



13. The Fo'urth Inferior Mesenteric Artery, arising at the level 

 of the posterior end of the left kidney, supplies the last pai't of 

 the intestine. 



14. The Posterior Left Renal Artery resembles its fellow on the 

 right, save that it does not send a branch to the oviduct, 



15. The Posterior Oviducal Arteries are a pair of artei'ies 

 running to the posterior ends of the oviducts. In addition to 

 this there may be one or two small twigs going to the rectum. 



16. The Rectal Artery is a small vessel supplying the last part 

 of the rectum. 



An Epigastric Artery is present, and it appears to be similar to 

 that described by Beddard (1) in Ophioj)hagus bungaris, that is, 

 it runs along the bodj'-wall in the mid-ventral line in close con- 

 nection with the epigastric vein, and is fed by branches from 

 the carotid anteriorly and the fat-body posteriorly. Its precise 

 relations are somewhat difficult to make out, for it is a vessel too 

 small for individual injection, and in order to get a satisfactory 

 injection of the arterial system it is necessary to open the snake 

 from end to end, dissect away the skin, and free the gut to some 

 extent. This, however, necessitates cutting either the epigastric 

 arteiy itself or some of its small tributaries. 



The arrangement of the vessels in the male snake is very 

 similar to that just described for the female. All the arteries 

 anterior to and just posterior to the heart are precisely the same, 

 and it is not until the region of the urino-genital organs is 

 I'eached that we find any difference. 



Each testis receives one spermatic artery as is general in snakes, 

 which first runs to the supra-renal body, whence it sends branches 

 to the testis and also to the vas deferens. These two spermatic 

 arteries are each followed by another vessel that runs to the pos- 

 terior part of the supra-renal body and also supplies the vas 

 deferens for a considerable distance, that on the right side also 

 sends a, branch to the fat-body. 



