1906.] VASCULAR SYSTEM OF THE HELODERM. 609 



and thus forms a pai^t of the hepatic portal system. On the right 

 side of the liver, a little process of liver-substance juts out to 

 meet the vein. This does not occur in the case of the left-hand 

 vein. The arrangement of oviducal membrane and the vein 

 which it bears appears to me to be exactly the same as a corre- 

 sponding series of structures which I described some time ago in 

 the Chamteleon*. 



Epigastric Veins. — These veins va. Heloder^ma (text-fig. 99, p. 602) 

 form a median unpaired system unlike the corresponding veins of 

 Varanibs. The principal vein of the system enters the liver very 

 anteriorly quite close to the end of that organ. The epigastric 

 generally, it is to be observed, is connected with the liver well in 

 front of the entrance of the umbilical vein. The main stem of the 

 epigastric was broken off, and a corresponding break on the largest 

 branch of the abdominal vein may perhaps indicate the junction 

 of the two. The main stem, whose actual course I am thus unable 

 to map, gives off a backwardly running branch which extends 

 beyond the liver. This latter stem is also connected directly with 

 the liver itself by two branches which it gives off just before ending 

 in the main stem of the epigastric. These form an anastomosis 

 with each other, and there are altogether formed three exits into 

 the liver, in addition, of course, to the main epigastric stem. 



Arterial System. — Dr. Shufeldt, in his memoir already referred 

 to t, has made a few comments upon the arteries arising from the 

 aorta behind the heart. He has not, however, dealt in any way 

 with the arteries at their point of origin from the heart. The 

 general arrangement of the exits of the arteries does not seem to 

 me to differ from what is found in the Lacertilia generally. The 

 heart also is bound to the pericardium by the tag which is so 

 general in the group. On the right side, the systemic trunk and 

 the carotid run side by side for a long distance after their 

 emergence from the common trunk by which they originate from 

 the ventricle. The systemic trunk then doubles upon itself to 

 pass back towards its point of junction with the aorta of the 

 opposite side of the body, the carotid continuing its forward 

 course. There is not the least trace, that I could discover, of the 

 ductus Botalli joining the systemic and carotid arches, which is so 

 prevalent among the Lacertilia. The contact between the two 

 trunks concerned is so close and exists for so long a space, that 

 there is, so to speak, every opportunity for the connection to have 

 been presei-ved. Yet it is absent. In this feature Heloderma 

 obviously agrees with Varanus and Amphishcena, in which genera 

 there is no such ductus Botalli to be found. 



The left aortic arch gives off no branches. The right aorta 

 gives off several pairs of intercostals as well as the subclavians, 

 which, as in many Lizards, arise the one behind the other. As 

 is the rule elsewhere, the left subclavian arises behind the right. 

 Yery shortly after the junction of the two aortse arises a slender 



* "Contributions to the Auatomj- of the Lacertilia," P. Z. S. 1904, vol. ii. p. 9. 

 t P. Z. S. 1S90. 



41* 



