1905.] AXATOMY OF THE FRILLED LIZARD. 17 



when it immediately gives ofi" a branch to the pectoral muscles. 

 After this the artery again perforates the body- wall close to a rib 

 aiid reappears upon the peritoneal face of the ventral musculature, 

 where it runs back and constitutes the epigastric. The conditions 

 which obtain in this genus are not universal among the Lacertilia. 

 The origin of the epigastric in Monitor is described by Corti *" 

 as being quite different. I can confirm this. It originates in the 

 Monitor from the carotid artery before it divides into two, but 

 still some way in front of the heart. 



The relationship between the intercostal and oesophageal arteries 

 is worth remarking upon in this Lizard. The left aorta is not, as 

 it appears, concerned with the circulation of either the oesophagus 

 or the body- wall t. But the right aortic arch gives off brandies 

 to both. There are two pairs of intercostals in front of the union 

 of the two aoi-tfe ; both of them on the i-ight side only give off a 

 twig to the walls of the oesophngus. After, tliat is posteriori}^ to, 

 the junction of the two aort;>^, one trunk ai'ises on each side of the 

 aoi'ta, which branches into an intei'costal ond an oesophageal 

 branch. From this point backwards the branches to the aH- 

 mentai'V canal ai'ise sepaiately fi'om the intercostals. On the 

 riglit side there are foiu- of these arteries, on the left only two. 

 There is not, therefore, an accuratelv paii-ed nirangement. 



It is notewoi'thy that the intercostal arteries J do not plunge 

 so deeplj" into the musculature of the back as they do in some 

 Lizards ; the arteries in question can be followed for a long 

 distance towaixls the ventral extremities of the ribs, h'ing as they 

 do very superficially in the musculatui'e. In Iguana, on the other 

 hand, the arteries in question are lost to view directly the}'' touch 

 the dorsal musculature on either side of the middle line. 



It does not appear that the aorta gives ofi" in the gastiic region 

 any branches to the livex' ; the hepatic artery, which is single, aiises 

 as a branch of the coeliac. It is important to remark this fact 

 because in some Lizards there are such arteries. In Lacerta 

 galloii, for example, each of the last two intercostal arteries which 

 lie in the liver region gives ofi" a bi'anch to that organ, which 

 bi-anches lie close to the dorsal parieto-hepatic veins. In this 

 particular Iguana agrees with Uromastix. 



Skull. — The skull of Chlamydosaurus is much like that of its allies 

 Ainphibolurus and Physignathus. On the whole, it comes nearer 

 to the former than to the latter, as the following facts tend to 

 show. It has also peculiarities of its own. On a general aspect 

 of the skulls the supratemporal fossa is seen to be very much more 

 elongated in Physignathus than in the other two genera. This 

 is actually due to the greater proportionate length of the metlian 

 unpaired portion of the parietal in Physignathus. The I'elative 

 lengths of the median portion of the parietal and the divei-ging 



* ' De systemate vasornin Fsammosauri c/risei,' 1S47. 



t Calovi, however, tig'ui-es an u'sopbageal artery arising- from the left aorta just at 

 juiu-tion with the right, and no others on either rig'lit or left half arch. 

 X These arteries are deliberately not dealt with by Calori, 



Proc. Zool. Soc— 1905, Vol. I. No. II. 2 



