18 MR. F, E. BEDDARD ON THE [Jan. 16, 



I have had the opportunity of compai-ing the structure of the 

 kidneys in the two young Eunectes notcetcs with the strvictiire of 

 those of an adult male of the same species. There is in the adult 

 no forwaid prolongation of a narroAver region of the kidney. The 

 oi'gans are of the noimal Ophidian foim, of equal diameter 

 throughout, and ending antei'iorly in a bkint rounded extremity. 

 That there may have been some microscopic traces in the tissues 

 surrounding the sperm-duct is of couise possible ; but there was. 

 nothing obvious to the naked eye. This state of afiairs in the 

 adult snake confirms, as I think, my opinion that the narrow 

 anteiior region of the renal organ in the newly-born young is to 

 be looked upon as mesonephros. I may observe that the testes are 

 veiy long bodies, and that that of the right side extends as far 

 forward as the gall-bladder. The growth of the testis may account 

 for the disappearance of the mesonephric portion of the renal organ. 

 With the disappearance of the supposed mesonephros there is 

 correlated, perhaps in this species but not in some other Boids, 

 the disappeai-ance of the posteiior caidinal vein, which, as I 

 describe in this paper, accompanies that gland in the young- 

 snakes. 



Umbilical Vein. — The umbilical vein was not absorbed in either 

 specimen. I was able to trace it along its whole course in the 

 body from the navel onwards to the antei-ior end. The conditions 

 which obtain in this snake show that Prof. Hochstetter's discovery 

 of the independence of the imibilical vein from the anterior abdo- 

 minal of the adult applies to Eunectes as well as to the reptiles 

 {Lacerta and Tropidonotus) whose development he studied. There 

 were two veins to be seen running fi-om the umbilical aperture. 

 The right-hand vein had the longest course, and is, 1 take it, the 

 representative of the right umbilical vein. The second vein was 

 traced along Meckel's divei-ticulum to the alimentaiy canal, where 

 it joined the poital system. This vein is, as I think, the omphalo- 

 meseraic. The umbilical vein pursues a stiaight course between 

 the two fat-bodies and over the gall-bladder. Arrived at the liver, 

 it passes beneath this organ, between it and the ventral body-wall. 

 There were no blanches to be detected anywhere, and there was 

 certainly no connection between the vein and the two anterior 

 abdominal veins at any point that I could ascertain. Indeed it 

 was easy to observe the umbilical \e\\\ i-vuming acioss the anterior 

 abdominals. The vein is fairly closely attached to the ventral 

 parietes in the region of the liver. It gives oft' no branches to the 

 liver, with which it has no relations save those of superposition. 

 At the extreme anterior end of the liver the umbilical vein joins 

 the vena cava posteiior just where the latter emeiges from the 

 liver. The two then run as one vessel to the heart. It is for the 

 reason that the umbilical vein joins the vena cava that I regard 

 it as the right-hand of the two primitive umbilicals. For in 

 Hochstetter's figure* illustrating the relation of these various veins 



* Moiph. Jalirb. xix. 1892, pi. xvii. fig. 15, V.u.d. aud V.u.s. 



