504 ME. F. E, BEDDARD ON THE VASCULAR AND [May 1, 



enters a distinct foramen larger than itself, formed in the tendons 

 exactly in the middle line. Before entering this foramen it gives 

 off a slender branch to the oesophagus. The intercostal artery 

 can then be plainly seen to divide into two. 



Erythrolamprus has only one gastric artery proper. This arises 

 from the aorta about on a level with the posterior end of the 

 liver*. The following superior mesenteric artery arises from 

 the aorta about on a level with the gall-bladder. It sends off, of 

 course, a gastric branch. The number of gastric arteries varies 

 much among Snakes t, and it is therefore of importance to record 

 the fact, though its systematic value is not yet apparent. 



The azygos vein of Erythrolamprus is in some ways remarkable 

 as compared with that of other serpents. For it is particularly 

 short though its branches are of considerable calibre. There are, 

 in fact, only three branches, supplying as many intercostal spaces, 

 which unite to form the single azygos trunk. This lies on the 

 right side of the body, and of coui-se joins the anterior vertebral 

 vein before the latter enters the heart. This is apparently shorter 

 than the azygos of any snake yet described. The azygos of 

 Coronella getula is just larger — four interspaces. 



In Coluber corais the single azygos vein also lies on the right 

 side of the body. It is, however, a little more extensive though 

 perhaps slighter. It supplies six intercostal spaces. It is to be 

 noticed that in both these Colubrines the azygos vein is of very 

 limited extent as compared with the P}d:honine and Boine Snakes, 

 speaking generally, for Eunectes is an exception. This fact is in 

 correspondence with the generally limited development of super- 

 ficial parietal veins in non- Boine Snakes as compared with the 

 Boidse. Even in Eryx, though a genus containing small-sized 

 species, the azygos is, as I have pointed outj, comparatively long. 

 I may take this opportunity of pointing out that in Python regius 

 — a small Python — the azygos extends over about 15 vertebrae, 

 to 2 inches or so behind the heart. 



The vena cava inferior of Coluber corais shows an interesting 

 vestige of the umbilical vein. ISTear to the anterior end of the 

 Kver the vena cava has a short diverticulum, which seems hardly 

 to be pervious, lying to the left side and extending obliquely 

 backwards. I take it that this seam is the equivalent of the thick 

 branch of the same vein in the same position which I have 

 described in Python sebce §, and which I then regarded, and still 

 regard, as a last remaining fragment of the embryonic umbilical. 

 It is clearly even more rudimentary in the present species. 



* I take this opportunity of noting that in JErythrolamprus eesculapii there is a 

 detached fragment of the liver lying upon the post-caval vein about an inch behind 

 the extremity of the liver. This is quite analogous to the division of the pancreas 

 and of the spleen which is to be seen in other Snakes. It is also to be compared to 

 the extremely thin posterior end of the liver in Corallus {vide infra, p. 518). In 

 these cases the gland appears to be in course of reduction in length. It is possible 

 that this is connected with a shortening of the body generally which has con- 

 spicuously taken place in certain Vipers. 



t Beddard, " Circulatory System in Ophidia," P. Z. S. 1904, vol. i. p. 331. 



t P. Z. S. 1904, vol. ii. p. li9. § P. Z. S. 1906, vol. i. p. 28. 



