606 MR. F. E. BEDDARD ON THE [May 29, 



upon the right side of the body, its usual position not so much in 

 the Lacertilia as in the Ophidia generally. 



It is of very limited extent in the present lizard, and after 

 reaching the neighbourhood of the vertebral column plunges at 

 once into the thickness of the parietes. It appears on the surface 

 for a brief intei-val between the two following intercostal arteries. 

 Five intercostal arteries then intervene before the next appearance 

 superficially of the vertebral vein, which is here developed iipon 

 both sides of the vertebral column. The longitudinally running 

 vein of the left side is the more important of the two and draws 

 blood from six intercostal spaces ; the right-hand vein is shorter 

 but developed in the same region of the vertebral column as the 

 left. The two vessels join and enter the liver near to its anterior 

 end together by a common trunk. This trunk receives before it 

 reaches the liver a branch from the stomach, the gastro-hepatic, 

 which is in its turn composed of two vessels, one of which runs along 

 the stomach forwards and the other passes along the stomach 

 towards its posterior end. This posterior gastro-hepatic vein has 

 other rather unusual relations with the portal system. It gives off 

 a small branch which goes at once to the liver. Posteriorly it 

 does not communicate with the general portal system of the 

 alimentary tract as in other Lizards, but ends by joining the anterior 

 abdominal vein behind the point where the latter receives the 

 intestinal portal. The somewhat complicated relations of these 

 several veins will perhaps be rendered clearer by an inspection of 

 the accompanying diagram of their course (text-fig. 101). In 

 possessing that anterior system of parieto-hepatic veins which are 

 connected with the gastro-hepatic veins, Heloderma does not 

 merely differ from the more typical Lacertilia, but agrees with 

 the Boine snakes, the snake-like Lizard Ophisaurus* , with Hat- 

 teria, and, as will be seen presently t, with the Yaranidfe, though 

 to a less extent with these also aberrant Lizards. The entire 

 separation of the gastric from the intestinal portal system is also 

 noteworthy ; and it will be obvious that, in spite of the points of 

 resemblance with other Squamata insisted upon, the details of 

 this part of the venous system are peculiar to Heloderma and 

 distinguish it from other Lacertilia. 



Heloderma possesses, as do all other Lacertilia which have been 

 examined, a series of veins entering the light lobe of the liver 

 close to its posteiior extremity, the posterior doi^sal pa7^ieto-kepaiic 

 veins. 



These vessels originate by several roots, which unite to form one 

 trunk as in Varanus. There are four separate roots, which arise 

 from the parietes on the right side of the body and lie between 

 three intercostal arteries. The single trunk formed by their 

 union enters the right lobe of the liver close to the postcaval 

 vein, and by the aid of a fold of membrane which, as in so many 



* Beddard, P. Z. S. 1905, vol. ii. p. 474. 

 f Infra, p. 616. 



