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Show 1905.] ANATOMY OF THE FRILLED LIZARD. 17 when it immediately gives oft a branch to the pectoral muscles. After this the artery again perforates the body-wall close to a rib and reappears upon the peritoneal face of the ventral musculature, wheie 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 f. But the right aortic arch gives off branches to both. There are two pairs of intercostals in front of the union of the two aortse; both of them on the right side only give oft' a twig to the walls of the oesophagus. After, that is posteriorly to, the junction of the two aorta?, one trunk arises on each side of the aorta, which branches into an intercostal and an oesophageal branch. From this point backwards the branches to the a'i-mentary canal arise separately from the intercostals. On the right side there are four of these arteries, on the left only two. There is not, therefore, an accurately paired arrangement. It is noteworthy that the intercostal arteries + do not plunge so deeply into the musculature of the back as they do in some Lizards; the arteries in question can be followed for a long distance towards the ventral extremities of the ribs, lying as they do very superficially in the musculature. In Iguana, on the other hand, the arteries in question are lost to view directly they touch the dorsal musculature on either side of the middle line. It does not appear that the aorta gives off in the gastric region any branches to the liver ; the hepatic artery, which is single, arises as a branch of the coeliac. It is important to remark this fact because in some Lizards there are such arteries. In Lacerta galloti, for example, each of the last two intercostal arteries which lie in the liver region gives off a branch 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 Amphibolurus 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 median unpaired portion of the parietal in Physignathus. The relative lengths of the median portion of the parietal and the diverging * ‘ De systemate vasorum Psammosauri grisei,' 1847. f Calori, however, figures an oesophageal artery arising from the left aorta just at junction with the right, and no others on either right or left half arch. J These arteries are deliberately not dealt with by Calori. P roc. Z oo l . S oc.- 1905, V o l . I. Xo. II. |
