1907.] OF OERTAIX SPECIES OF SQUAMATA. 45 



There is thus a simphfication in the coiling of the gut in this very 

 small species which is not so sti'ongly marked in the rather larger 

 but still small Ch. piirtulus. It is not without interest to note 

 this apparent relation between smallness of size and simplification 

 of structure shown also in the lungs of these species, as has been 

 already commented upon *. 



(2) Soine Notes upon Ohamseleolis. 



This Lizard is placed among the Iguanidce in spite of its super- 

 ficial likeness to a Chamseleon. Indeed this superficial likeness is 

 not after all very striking, and depends mainly upon the fact that 

 the head is prolonged behind and above into a parietal crest. 

 Nevertheless it is of advantage to be able to record a few facts in 

 the visceral anatomy which distinctly confirm the placing of this 

 genus in the immediate neighliourhood of Iguana. It has, more- 

 over, its own peculiai'ities as compared with that genus ; and 

 therefore as a contribution to the visceral anatomy of the Lacer- 

 tilia I am laying before the Societj^ such facts as I have gathered 

 from a dissection of a female individual. The existing knowledge 

 of the anatomy of the Lacertilia shows that there are four 

 marked structural features in which all the Iguanidse that have 

 been examined agree with each other, and the combination of 

 which allows them to be defined. I shall, therefore, first of all 

 deal with these foui- points, which together prove that Chamoi- 

 leolis has been rightly placed among those Lizards. 



In the first place, the umbilical ligament which divides the two 

 liver-lobes and is attached to the ventral median line of the body 

 is a single ligament which runs continuously fi'om end to end of 

 the liver, without any trace of a posterior division upon the liver, 

 as I have lately figured in. Iguana "f. The gall-bladder is left to 

 the right of this ligament. In these particulars the umbilical 

 ligament of Chamcdeolis is precisely like that of Iguana, and there 

 is no need to illustrate the relations of the ligament by a figure. 

 I may mention that it is deeply pigmented. 



A second feature, which, though a small character, appears to be 

 a constant one, is the position of the intercostal arteries in relation 

 to the vertebrae. In Chamcdeolis, as in some other Iguanoids, 

 these artei'ies plunge into the thickness of the dorsal parietes 

 towards the posterior end of each vertebra ; in some other Lizards 

 they disappear from view at about the middle of each vertebra. 

 Of course, Chamcdeolis has the same regular arrangement of pairs 

 of these arteries as in other Lizards, a featui-e, indeed, which seems 

 to differentiate the Lacertilia from the Snakes, at least broadly 

 considered. 



Thirdly, Milani $, whose account of the Lacertilian lungs is the 

 most recent and comprehensive known to me, has found that in 

 the Iguanidae the lung is totally divided into two chambers, of 



* Swpra, pp. 39 & 41. 



t P. Z. S. 1905, vol. i. p. 12, fig. 7. 



t Zool. .Jahrb. (Abtli. f. Anat.) vii. p. 545. 



