1905.] ANATOMY OP THE FRILLED LIZARD. 15 



MitsGular fibres in the Mesenteries. — The existence of muscular 

 fibres in the mesenteries of Saurians is well known *. That they 

 have not been recorded in the genera with which I deal in the 

 present communication is less important to me than to note 

 their distribution in those mesenteries. 



The aorta in Uromastix lies between the two halves of the 

 dorsal median mesentery, which are attached to it laterally and to 

 the CBSophagus above in the thoracic region of the body. The 

 two mesenteries spring from the sides of the vertebrfe ; they are 

 much invaded by muscular fibi-es which have a dorso -ventral 

 direction. The pulmonary mesenteries vary in this respect ; 

 those which bind each lung to the dorsal parietes are free from 

 muscular fibres except towards their posterior region ; on the 

 other hand the (right) pulmo-hepatic ligament is much more 

 invaded by muscular fibres. The mesogastrium and mesentery 

 proper are not muscular, in which the formei- contrasts, as already 

 pointed oiit, with the hepato-colic ligament. The oviducal 

 mesenteries are very muscular. The umbilical ligament is also 

 provided with muscular fibres. The gastro-hepatic membrane, on 

 the other hand, is very slightly if at all muscular. 



The three other genera which I compare with each other and 

 with Uromastix show differences as to the amount of the invasion 

 of the several mesenteries by muscular tissue. In considering the 

 ligament which binds the liver to the ventral parietes (umbilical 

 ligament) I have already referred to its partial muscularity in 

 Physignathus. The muscles in question are very strong at their 

 insertion on to the ventral body- wall ; besides giving ofi' fibres to 

 the liver as already described, they give off other fibi-es which run 

 along the gastro-hepatic ligament and pass out on to the oesophagus. 

 There is no question here, it must be noted, of a muscular con- 

 nection between the liver and the cesophagus and stomach. The 

 fibres cross this membrane. Similarly the pulmo-hepatic ligament 

 on the opposite side is traversed by muscular fibres, arising, how- 

 ever, in this case from the mesogastrium, which pass out on to 

 both liver and lung. From this it results that the free extremity 

 of the lung is attached by muscular fibres to the dorsal parietes 

 behind the liver. The pulmonary ligament itself of this lung 

 (the right), i. e. that which attaches the lung to the dorsal parietes, 

 is completely free from muscle. In the case of the left lung, 

 however, which possesses no pulmo-hepatic ligament, the pvilmo- 

 parietal ligament, though generally free of muscle, has a few slips 

 at the very tip of the lung which may correspond physiologically 

 with those of the right side, though their relation to the pulmonary 

 ligament is diff'erent. The mesogastrium is also muscular ; but 

 the fibres by no means form such a thick dense mass as they do 

 in Ghlamydosaurus, which will be dealt with immediately. They 

 are more sparsely scattered, with wider non-muscular intei'vals. 



. •. 

 * Briicke, "Uebev ein in Peritonajum von Tsammosauriis .(//'/seHs aufgefuuJencs 

 System von glattcn MuskeUascri)," SH. Wicu. Akad. vii. p. 2k). 



