1907.] OP CERTAIN SPECIES OF SQUAMATA. 67 



lung this distance was only 21 mm. A second specimen showed 

 pi^ecisely the same relations in all these points of structure. 

 Contrasted with this (compare text-figs. 18, 19) are the different 

 conditions observable in Varmiics exanthematicus. In the latter 

 species (text-fig. 18, p. 65) the two branches of the bronchi were 

 exactly symmetrical and each was situate 33 mm. from the bifurca- 

 tion of the bronchi. Only the right lung gave ofl;' a forwardly 

 directed lobe situated on the inner side of its bronchus. There was 

 nothing to correspond in the left lung. I have not been able to 

 compare these conditions with those of many other species of 

 Varanus. But in both V. ocellatus and V. niloticios there was 

 precisely the same asymmetry in the relative positions of the 

 branch of the bronchus, which in all cases lies behind the aorta of 

 its side. 



Simimary of more important neio Facts contained in this 

 Comtnunicat ion. 



In view of the fact that very few genera and species of 

 Lacertilia have been studied anatomically, it is a little difficult at 

 pi-esent to difierentiate between more and less important structural 

 details as evidence of affinities between different genera. The 

 following resume, therefore, will be necessarily only an attempt to 

 lay stress upon what appear at present to be the more important 

 new facts which I have set forth in this communication. 



(1) The pancreas in the Lacertilia, as already known, differs in 

 different genera. I have added to the existing knowledge some 

 new facts with regard to genera and species not examined by 

 others. It appears from this that the chief variability in the 

 pancreas consists in the presence or absence of a splenic lobe and 

 in the relations of the latter to the spleen. The classificatory 

 importance of the facts does not appear to be great ; since, though 

 the Iguanoids, Iguana and Liolcemus, are like each other in the 

 relations between the splenic lobe of the pancreas and the spleen, 

 we find in Varanus and Chamceleon differences between different 

 species in these points. The pancreas is nearly always a compact 

 gland ; but not so in Zonurus. 



(2) The variations in the structure of the viscera among the 

 Ohamseleons concern principally the proportions between the two 

 lobes of the liver, the form of the diverticula of the lungs and the 

 absence or presence of these, the degree of pigmentation of 

 the body-cavity, and the degree of coiling of the intestines. 



(3) The variations in the structure of the viscera in the 

 different species of Varanus concer-n principally the presence or 

 absence of a bile-duct network and certain minute differences in 

 the lungs. It seems possible that those species with a round 

 nostril are distinguished from those with an oblique slit-like 

 nostril by the possession of this netwoi-k. 



(4) The simplicity of .;truct-are which is often associated with 

 small-sized forms as compared with their allies of larger size is 



