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Show 1889.] THE BODY-CAVITY IN LIZARDS, ETC. 467 as being very peculiar ; but it is led up to in other genera of the Teiidae. Thus, in Ameiva and Callopistes the median ventral ligament is, as it were, expanded laterally behind the liver, or it may be said to give off at right angles on either side a membrane which dorsally becomes attached to the hinder part of the liver. In Ameiva and Callopistes, however, the transverse vertical septum thus formed is not continuous with the lateral walls, and there is a free passage on either side. But in Tupinambis (see Plate XLVIII. fig. 32, which is a view of the septum from behind, ventral side uppermost) the subdivision of the body-cavity is much more complete. On the right side there is only a very small aperture of communication (o) between the pulmohepatic and intestinal cavities. This is situated on the dorsal side external to the inferior vena cava and the attenuated extremity of the right liver-lobe, which is represented as visible through the septum. On the left side there is a larger, but still comparatively small, aperture (o') also dorsally situated. Figs. 33 & 34 give side views, ventral side uppermost, of this post-hepatic septum (ft), and the organs contained in the pulmohepatic cavity in front of it. The whole lateral body-wall next the observer is supposed to be removed. In fig. 31, on the right side (left of observer), only the ventral part of this septum is displayed, the more dorsal part lying concealed beneath this, together with the extremity of the right liver-lobe. This post-hepatic septum I have throughout indicated by the same letter (/3) as the more ventral, or omental, part of the post-hepatic septum of birds, in accord with my opinion that they are homologous ; since the position of the foramen of either side seems to make it clear that there is no component growing in from the dorsal side corresponding to the oblique abdominal septum of the bird. This is just what we should expect, there being no development of abdominal air-sacs. The difference between the adult condition of these Teiidee and that of the other type of Lizard would seem to imply that the vena cava inferior of the former, instead of developing, as in Lacerta, Gallus, and Lepus, in tissue continuous with the posterior part of the pulmohepatic ligament, has arisen in a lateral transverse outgrowth of the dorsal part of the longitudinal median septum or mesentery, in fact in a membrane situated altogether posterior to the place where the pulmohepatic recess would lie if present. The need of some such transverse membrane, in the absence of the pulmohepatic ligament, to carry the vena cava inferior to the liver, accounts for the dorsal portion of the post-hepatic septum in the Teiidee. To the relations of the lungs in the Teiidae I have already referred (p. 465). V. ON THE BODY-CAVITY OF THE CROCODILIA. Turning now to the Crocodiles. In the absence of any data as to the development of the septa in these animals (such as we possess in |
