1906.] ON THE VASCULAR SYSTEM OF THE HELODERM. 601 



3. On the Vascular System of Heloderma, with Notes on 

 that of the Monitors and Crocodiles. By Frank E. 

 Beddard, M.A., F.R.S., &c., Prosector to the Society. 



[Received May 11, 1906.] 

 (Text-figures 99-106.) 



Although much work has been done upon the blood-system of 

 the Lacertilia, especially by Rathke and Hochstetter *, there 

 remain a number of important genei-a of which we have at present 

 either no knowledge whatever, or the very slightest only. Among 

 these is the genus Heloderma, with the general anatomy of which 

 the recent investigations of Boulenger, Stewart, and particularly 

 Shufeldt t have made us well acqviainted. In the present com- 

 munication I bring before the Society some facts concerning the 

 blood-vessels of this Lizard in continuation of former contributions 

 to the anatomy of this Order of Reptiles J. 



Having had the oppoi'tunity, during the last year or two, of dis- 

 secting seveiul examples, comprising several species, of Varamis, 

 I incorporate these notes into the pi'esent communication for the 

 reason that Heloderma is in some respects not very remote fi'om 

 Varanus §, and indeed shows certain apparent resemblances to 

 that genus in the ai'rangement of the blood-vessels, as will be 

 pointed out in the course of the following pages. 



Since both in Heloderma and Vai'amcs there is a departure in 

 many directions from the arrangement of the blood-vessels found 

 in other Lacertilia (e. g. Iguana, Skinks, Geckos, Ophisaurus, 

 AmphisbcEna, Anguis), a,nd on the whole in the direction of greater 

 complication, it seemed to me important to compai'e the ascer- 

 tained facts with those relating to the Crocodilia, since the vascular 

 system of the Crocodilia is perhaps the most advanced among the 

 Reptilia. In this department I am able to add some details to the 

 classical treatise of Rathke, in axldition to the facts accumulated 

 by Jacquart and Hochstetter, whose contributions will be referred 

 to on a later page. Of the Crocodilia I have been able to dissect 

 several species belonging to more than one genus. 



(1) O71 some Veins and Arteries in Heloderma suspectum. 



In a specimen of Heloderma sitspecttom which died in the 

 Society's Gardens in January of the present year, the veins wei-e 

 turgid with blood, and therefore in an excellent state for 

 anatomical observation. I had the arterial system injected, and 

 am therefore able to give, as I trust, some reliable notices of various 



* Morph. Jahrb. xix. 1893, were earlier papers are referred to. 



t Boulenger, P. Z. S. 1891, p. 109 ; Stewart, ihid. 1891, p. 119 ; Shufeldt, ibid. 



1890, p. 148. 



t In P. Z. S. 1904 and 1905. 



§ This is not a prevalent view though adopted by Banr. See Boulenger (P. Z. S. 



1891, p. 116) for discussion of the subject. 



