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Show 1905.] ANATOMY OF THE FRILLED LIZARD. 15 Muscular 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 oesophagus above in the thoracic region of the body. The two mesenteries spring from the sides of the vertebra: ; they are much invaded by muscular fibres 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 former contrasts, as already pointed out, 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 oft' fibres to the liver a^ already described, they give off" other fibres 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 connection between the liver and the oesophagus and stomach. The fibres cross this membrane. Similarly the pulmo-hepatic ligament on the opposite side is traversed by muscular fibres, arising, however, 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 pulmo-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 different. The mesogastrium is also muscular; but the fibres by no means form such a thick dense mass as they do in Chlaviydosaurus, which will be dealt with immediately. They are more sparsely scattered, with wider non-muscular intervals. * Briicke " Uebev oin in Peritonaeum von Psammosaurus g rise us aufgefundenes System vcmglatten Muskelfasern," S15. Wien. Akad. vii. p. 210. |