1907.] OF CERTAIN SPECIES OF SQUAMATA. 63 



that the bronchus traverses a considerable distance within the 

 lung before it disappears. My own illustration will show that 

 the semirings of the bronchus are complete for a considerable 

 distance, and perfectly easily recognisable, since they show no 

 particular differences from the semirings in the extrapulmonary 

 region of the bronchus. The bronchus communicates with the 

 lung by copious apertures, which are not situated in the region 

 of the bronchus corresponding to the fibrous band which unites 

 the tips of the semirings in the extrapulmonary region of the 

 lung ; these apertures would seem to be rather breaks in 

 continuity of the semirings themselves. Their disposition is 

 thus reminiscent of the way in which the rudimentary lung of 

 certain Snakes arises from the bronchus. There is a simple hole 

 in the bronchus which leads into the lung in the case of those 

 Snakes. 



In a paper communicated to this Society a good many years 

 since* 1 described the complicated branching of the cystic duct 

 and its anastomosis with the hepatic duct in Varanus salvator. 

 I have since then discovered that the same network, comparable 

 to that which is found so generally among the Ophidia, occurs 

 also in V. goiddii, though it is in that species rather less developed 

 than in V. salvator. Quite recently I have dissected out the bile- 

 ducts in V. niloticus^ of which species I have had the opportunity 

 of examining several very small examples preserved in spirit. 

 I had one of these injected from the gall-bladder, and the injection 

 (chrome-yellow i-ubbed up in olive-oil) ran readily along the 

 branches of the cystic and hepatic ducts. The accompanying figure 

 (text-fig. 17, p. 64) is fairly accurate (but I fear not absolutely 

 so) as regai-ds the network, which, as will be seen, is much like 

 that of V. salvator, but perhaps not quite so complicated. Moi"e- 

 over, when once the hepatic and cystic ducts have left the surface 

 of the gall-bladder there are apparently no further anastomoses 

 between them, as there are — though to a limited extent — in 

 V. salvator. On the other hand, there are some species of Varanus 

 in which there is no network formed by the bile-ducts on their 

 emergence from the gall-bladder (as is also found among the 

 Ophidia). To some of these I have referred in my communication 

 just quoted. I have since carefully examined Varaoitbs exanthe- 

 maticios, and find that the cystic duct emerges as, and continues 

 to be, a simple duct throughout. The same is the case with 

 V. griseus. It is not wise perhaps to genei'alise on these few 

 data ; but so far as the facts go they agree with an important 

 external character by which the species referred to may be 

 grouped . In V. salvator, V. goiddii, and V. niloticus the nostril is 

 a circular aperture, while in the other species mentioned it is 

 obliquely placed and slit-like. 



In all the species of Varamis that have been referred to in the 



* P. Z. S. 1888, p. 106. The illustrative figure (fig. 4, p. 105) has been copied in 

 Gegenbaur's ' Vergl. Anat. Wirbelth.' 



