112 MR. F. E. BEDDARD ON THE [May 17, 



In Eryxjohni the same series of oesophageal branches arising from 

 intercostals ai-e present. They arise from intercostals partly 

 belonging to the right aortic arch, and partly to those arising from 

 the common trunk. The third intercostal, after the union of the 

 two aortse, gives off a slender vessel which runs forward and joins a 

 vessel arising fi'om the last but four of the intercostals belonging 

 to the right aorta. This longitudinal trunk gives off several lateral 

 vessels. The third, fourth, and fifth of the intei-costals of the 

 right aortic arch also give off single oesophageal vessels. 



I have pointed out in another paper* that the Lizard Pygopus 

 is unusual by reason of the fact that some of the visceral arteries 

 arise from intercostals instead of directly and independently from 

 the aorta. In Eryx johni precisely the same mode of origin 

 occurs not only for oesophageal arteries, but for a fat-body artery. 

 This springs from the right-hand intercostal of the seventh pair 

 after the posterior renal artery. 



I observed the exact converse of this state of affairs in 

 Tropidonotus fasciatus. The right aorta gives off intercostal 

 branches, but no twigs to the oesophagus that I could find. On 

 the other hand, a single parietal vessel, accompanied closely by a 

 vein, enters the parietes a good way to the left of the middle 

 dorsal line and arises unmistakably from the left aortic arch, 

 which also, of course, gives off several branches to the oesophagus. 



Gastric arteries. — The fact tha,t in Eryx there are only two t and 

 in Python spilotes only three gastric arteiies, appears to me to be 

 an archaic point of structure in these Boid snakes. Among the 

 Ophidia generally there is frequently a large number of gastric 

 arteries. For example, in the genus Coluber 1 have found as many 

 as ten or eleven. The reduplication of these and other arteries, 

 so characteristically Ophidian, seems therefoi'e obviously to mark 

 the more specialised members of the group. The absence of, or less, 

 reduplication is not therefore inconsistent with the less modified, 

 more archaic, structure. 



Ovarian arteries. — It is at least rare among snakes + for the 

 ai-teries supplying the gonads to arise fi'om the aorta opposite to 

 each other. As a rule one spermatic or ovarian artery follows the 

 other in relation to the asymmetrically placed gonads. Never- 

 theless in a female Eryx conicus the two ai'teries arose side 

 by side. They immediately follow, as is usual, the superior 

 mesenteric. The paired condition of these arteries seems to me 

 to be a primitive feature in the organisation of this snake. 



Renal arteries. — It is the general rule among the Ophidia for 

 each kidney to be supplied with a considerable number of arteries. 

 There are, for example, as many as eight in Coluber cateni/er. 

 Among such Boidje as I have examined, the number is invariably 

 one or two arteries only to each kidney. In Python sebce, Eunectes 



* Above, p. 12. 



f I could find only one in ISrt/x JoJini. 



X I have not myself observed a single instance in the Ophidia cxxept in the case 

 mentioned above. 



