1906.] VASCULAR SYSTEM OF THE HELODERM. 603 



ascertain, with any veins in the posterior region of the abdomen. 

 It runs, of course, upon the ventral side of the abdominal cavity 

 lying to the left of the anterior abdominal vein. This position 

 at first led me to think that the vein in question was a left 

 anterior abdominal vein, such as is met with in addition to a 

 right in the Orocodilia invariably and in the Ohelonia generally. I 

 think, however, that the facts which I have to state about this vein 

 disprove the idea that it is a second anterior abdominal vein and 

 prove it to be a persistent umbilical. This vein is by no means 

 a ligamentous rudiment such as Hochstetter has described and 

 figured * the umbilical to be in Anguis fragilis. It contains 

 plenty of blood ; but it looks rather like an artery owing to its 

 pink colour — due, I imagine, to thickish walls. It is, however, 

 not an ai-tery ; for anteriorly it could be followed between the 

 lobes of the liver ventrally, and perhaps about halfway along the 

 length of the liver was traced into communication with the vena 

 cava posterior, which latter, on separating the lobes of the liver, 

 can be seen lying between them. It could be distinctly observed 

 at the same time that various branches of the epigastric vein 

 (see p. 609) which enter the liver near the entry of the umbilical 

 did not communicate with the vena cava but entered the liver- 

 substance. There can be no confusion therefore of this presumed 

 persistent umbilical vein with a branch of the epigastic system 

 of veins. It is fui'ther to be noted that the umbilical vein is in 

 its relations to adjoining viscera more like that of birds than of 

 the Boidse, where alone among existing Sauropsida — so far as we 

 know at present — this vein persists in the adult. That is to say, 

 the vein is lost to sight until the two lobes are separated at about 

 the middle of the liver as in the Class Aves, instead of extending 

 beyond the liver as in the Python f for example, and joining the 

 vena cava in front of that organ. On another pagej 1 call 

 attention to the possible persistence of the umbilical vein in the 

 Monitor lizards, which vein, however, shoM^'s certain diflerences 

 from that which I describe in Heloderma as an umbilical. There 

 is no doubt, however, that the vein in Heloderma corresponds to 

 what is clearly the persistent umbilical in the Anaconda, &c. in 

 bearing no part in the cu-culation, i. e. in not being furnished 

 with branches. 



Anterior Abdoviincd Vein. — This vein is, as is universal among 

 the Lacertilia §, a single median vein, and was very full of blood in 

 the specimen which I dissected. The origin of the vein in the 

 pelvic region seems to me to be more like that of Varmius than of 

 such other Lizards as have been examined. Of Varanus arenarius 

 ( = F. griseus) Hochstetter |i has written : — " Ein zvi^eiter wich tiger 

 Differenzpunkt betriift die Lage der Wurzel der Abdominalvene, 



* Morpli. Jahrb. xix. 



f Beddaid, "Contributions to the Anatomy of the Ophidia," P. Z. S. 1906, vol. i. 

 p. 28. X Below, p. 611. 



§ Excepting: possibly Varanvs (see below, p. 611). 

 II Morph. Jahrb. xix. p. 467. 



