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Show 466 MR. G. W. BUTLER ON THE SUBDIVISION OF [Nov. 19, median ventral ligament behind it, and take a more or less oblique course across the liver. Sometimes there is more than one such on a side. I would call these the oblique ligaments of the liver. These ligaments, when present, appear, in certain cases, to be continuous with the membranes that bear the forward continuations of the Miillerian ducts (oviducts), and are specially noticeable in the case of the Chameleon, where they form broad sheets of membrane constituting a kind of ventral diaphragm 1. The oblique ligaments can be traced in Lacerta, Uromastyx, Ameiva, Chamceleon, and others, but their number, distribution, and degree of development is different in different forms ; and I call attention to them chiefly on account of the light they may throw on the nature of certain membranes in the Crocodiles. There are in these animals (cf. p. 469) certain well-defined ventral ligaments of the liver, which completely mark off the more median portion of each lobe from its antero-lateral corner, and seem to correspond to these inconspicuous ligaments in the Lacertilia, but not truly to anything in Birds. I am inclined to regard such oblique ligaments as complementary to the pulmo-hepatic ligaments; that is, to consider that they serve to unite the liver to the body-wall in those forms in which the tissue corresponding to the avian diaphragm, to which the last-mentioned ligaments are attached, does not itself become attached to the body-wall. The more or less marked folds of peritoneum, which carry the forward continuations of the Miillerian ducts, seem (cf. p. 462) to mark the line along which an avian diaphragm might be expected to arise; and they probably exercise one of the functions of a diaphragm, in rendering a certain protection to the lungs; but I would not advocate any closer homology between these membranes and the diaphragms of either Birds or Mammals. The relation of the lungs to the body-cavity in the Monitors is referred to in my paper on the " Fat-bodies," to be subsequently read, and I have nothing further to add here. (b) The Teiidce. The condition in Tupinambis teguixin (Tejus teguexim, Gray) is very interesting. W e have here (cf Plate XLVIII. figs. 31-34) a post-hepatic septum (ft), apparently homologous with the ventral (or so-called " omental ") portion of the post-hepatic septum in birds (the ventral side of which is shown in fig. 29, ft), and perhaps to the greater part of the post-hepatic septum in Crocodiles (figs. 40-43, j3). This well-marked post-hepatic septum at first strikes the observer 1 Such oblique ligaments do in their adult relations rather suggest part of the embryonic mammalian diaphragm. They attach the liver to the body-wall posteriorly and ventrally to the attachment of the liver to the lungs or mediastinum (compare with this Plate X L V I . fig. 4, dph.). |
