1906.] RESPIRATORY SYSTEMS IN THE OPHIDIA. 505 



It is to be noted that there is no development of longitudinal 

 trunks running along the vertebral column in the liver-region 

 which give off branches to the poi^tal vein. There are a number 

 of the branches to the portal ; but each of these emerges separately 

 from the parietes or is formed of the junction of two or three. 

 There is no extensive fusion such as occurs in the Boine Snakes 

 generally. I do not think that this absence of a longitudinal 

 trunk is due to the emptiness of the blood-vessels. It seems to 

 me to be an anatomical fact. 



The vena renalis advehens (text-figs. 87, 88, pp. 502, 503), as is 

 known to be the case in other Snakes, communicates directly with 

 the mesenteric vein underlying the gut*. Between this point 

 and the right kidney the renal vein receives about eight branches 

 from the parietes. In the case of the left kidney, which is neai'er 

 to the cloaca than the right, there are only five of these branches. 

 At the anterior end of the kidney the vein distinctly ends, though 

 at the very extremity. There is no continuation forwards such 

 as occurs so generally (? universally) among the Boidae and 

 occasionally (Zamenis gemonensis) among the Colubrines. Each 

 kidney also receives a special branch from the dorsal parietes, 

 which is not mentioned by Hochstettter in Tropidonotus. This 

 arises from the parietes at about the middle of the kidney and 

 from several intercostal spaces on the left side of the body, but 

 from one only on the right. In both cases these veins closely 

 accompany the second renal artery (reckoning from the anterior 

 end of the kidney). Their course, however, is rather different on 

 the two sides of the body. The vein of the left side (text-fig. 88) 

 perforates the kidney, or rather runs between the lobules of that 

 organ ; it ultimately joins the renal afferent vein. It is remark- 

 able that the corresponding vein of the right side of the body 

 is different in its relation to the veins of the kidney. It was 

 thoroughly injected, and therefore quite easy to follow. The vein 

 is seen to have no connection whatever with the renal afferent 

 vein of the right kidne}'', but it opens without doubt into the 

 renal efferent vein (see text-fig. 87) at a point roughly opjposite 

 to its point of emergence from the parietes. This anatomical 

 relationship is obviously very Lin expected, and it is quite possible 

 that we have here an abnormal state of affairs. 



The venous system of the hidneys in Coluber corais differs in 

 some details from that of other genera. The afferent renals, some 

 way before they reach the kidneys, give off two important 

 branches. One of these is to the dorsal parietes, and is a vein 

 which is very general among the Ophidia. The other forms with 

 its fellow of the opposite caiidal, which it meets at an angle of 180 

 degrees, what is practically the commencement of the inferior 

 mesenteric vein running along the dorsal surface of the intestine. 



* In Tropidonotus and Coluber asculapii, according to Hochstetter (Morph. 

 Jahrb. xix. p. 489), who thus confinns Schlemm and Jourdain as regards the former. 

 I have found this vein in Coluber corais, in Zamenis gemonensis, and Ancistrodon 

 piscivorus. ' 



