60 MR. F. E. BEDDARD ON THE ANATOMY [Jan, 15, 



good many facts in favour of such an alliance. On the other 

 hand, Dr. Shufeldt *, who has given us a comprehensive sketch of 

 the anatomy of Heloclerina, remarked that his own studies of the 

 Varanidje convinced him " of the fact that Heloderma is far 

 removed from that group, having very little structural affinity 

 with it." To these papers cited below, and to others quoted in 

 them, reference may be made for the views which have been 

 held with regard to the position occupied by the genus Heloderma 

 in the system. 



In recently dissecting examples of these two genera I have 

 noticed two structural features in which the two genera are similar 

 and by which they may be ditFe]:"entiated from any other Lacer- 

 tilians whose anatomy is known, so far as concerns the points in 

 question. The first of these is a feature in the anatomy of the 

 respiratory organs which has indeed been described in Varanus 

 but not in Heloderma. As to the former genus, Meckel f, 

 Giinther J, and Milani §, to whose investigations our knowledge 

 cif the anatomy of the respiratory organs in the Varanidfe is 

 chiefly due, describe a short branch given off by the bronchus 

 shortly after it has entered the lung ; this supplies the headward 

 extension of the lung which is so well marked in this genus of 

 Lizards. It is plainly figured by Milani ||, whose illustrations ^, 

 particularly a diagrammatic figure, show that this twig arises in 

 front of an aperture in the walls of the intrapulmonary bronchus. 

 Some of Milani's figures** also illustrate another somewhat im- 

 portant fact, which is that the bronchus until it gives ofTthe branch 

 to which reference has been made does not really lie within the 

 the lung, but outside of it. The lung in growing forward has 

 wrapped round the end of the bronchus. Though apparently 

 within, this portion of the bronchus is really morphologically 

 outside of the lung. The interest attaching to the exact relation- 

 ship between the bronchus, the lung-tissue, and the first branch 

 of the bronchus appears to me to be this : — that this independent 

 branch arising so eaidy from the bronchus is possibly to be compared 

 with the eparterial bronchus of the Mammalia. This comparison 

 is not suggested by Milani. In any case it is, so far as I am 

 aware, a structure that has not yet been described in any other 

 Lacertilian. A precisely comparable branch of the bronchus 

 occurs, however, in Heloderma, where its existence is an interesting 

 feature of resemblance to Varanus. I cannot find that any of 

 the writers ft who have described the lung of Heloderma have 

 noticed this — to my eyes, very striking — peculiarity of the lung. 

 Nor do the illustrations given by them show any signs of the 



* P. Z. S. 1890, p. 233. 



t Deutsches Arch. f. d. Pliys. 1818, Bd. iv. % P. Z. S. 1861, p. 112. 



§ Zool. Jahrb. (Abth. f. Aiiat.) vii. 1894, p. 581. 



II Loc. cit. Taf. 31. figs. 16-18. 



T[ Loc. cit. p. 581, fig. E, Taf. 32. figs. 19-21. 

 ** Especially fig. 20 of pi. 32 of his memoir. 



tt Shafeldt,'Zoc. cit. p. 202 ; Stewart, P. Z. S. 1891, p. 118 ; Miller, "The Structure 

 of the Lung," Journ. Morph. viii. 1893, p. 170. 



