52 MR. F. E. BEDDARD ON THE ANATOMY [Jail. 15, 



It is not safe upon these two last-mentioned examples to atteinpt 

 to draw any distinctions between the different species of Bitis. 

 It seems, however, to be most probable that they do not difier 

 widely from each other as regards the points under discussion, 

 whether they will ultimately be found to differ specifically or not. 

 It is, however, quite plain, in reviewing all the facts brought 

 forward in the present communication, that the position of the 

 umbilicus among Yipers is one that does at least characterise 

 some forms wdiich happen in the instances studied to be generi- 

 cally separated. 



(4) Some Notes upon the Anatomy o/Zonurus, with Special 

 Reference to the Hyoid. 



The following notes refer to three specimens of ZonurxLs 

 giganteus which I have had the opportunity of dissecting during 

 the last year or two. The anatomy of this Lizard is already to 

 some extent known through the work of previous observers. 

 The lungs have been dealt with by Milani * in his general account 

 of these organs among the Lacertilia, and the arteries of the 

 gastric and intestinal regions are described and figured by Hoch- 

 stettert. There remain, however, a few points to which it is 

 worth while calling attention as a further contribution to the 

 natural history of this Lacertilian. 



Of special importance — rather, however, from a general point 

 of view than as a particular contribution to our knowledge of this 

 Lizard — is the condition of the elements which together make up 

 the hyoid complex of bones and cartilages in this Lacertilian. 

 I am able to add to what I have to say concerning Zonurus a few 

 notes upon other genera of Lacertilia which I have dissected for 

 purposes of comparison. I commence with a brief resume of 

 some of the facts already known of this part of the skeleton. 



The hyoid and branchial arches of Lacertilia have not, as it 

 appears, been investigated in a very large number of genera. 

 Several are figured in the volume t of Bronn's 'Thierreich ' dealing 

 with the Lacertilia, while other genera have been illustrated by 

 subsequent writers §. Apart from differences in the form of the 

 individual elements of the hyoid complex there is substantial 

 agreement, according to these various writers. For contrary to 

 wha,t is to be found in the Chelonia— where the remains of the 

 hyoid arch proper is followed by two branchial bars considerably 

 developed — the Lacertilia are generally believed to be characterised 

 by the preservation in the adult of only one visceral arch follow- 

 ing the hyoid arch, which is stated to be the first branchial. 

 This statement occurs at any rate in such authoritative textbooks 



* Zool. Jahrb. (Abth. f. Anat.) vii. p. 545. 



t Movpli. Jahvb. xxvi. 



+ Reptilia, Bd. vi. Abth. iii. Taf. 72. figs. 2-8, & Taf. 107. figs. 24, 33. 



§ E. g., Gecko mauritaniciis, Gadow, Phil. Trans. 1888 B, pi. 72. fig. 10; SeZo- 

 derma siispectum, Shiifeldt, P. Z. S. 1890, pi. xviii. tig. 6 ; Clilamydosauriis and 

 JPJiysignathns, Beddard, P. Z. S. 1905, vol. i. p. 20, text-fig. 9, and p. 21, text-fig. 10. 



