OCR Text |
Show 1889.] THE BODY-CAVITY IN LIZARDS, ETC. 469 wall, without damage to the delicate septa and ligaments attached and passing into it. There appears to be a septum or " diaphragm " behind the lungs, d.a°, d.a° ; but this only extends for a short distance inwards from the ventral body-wall, as is seen by comparing the figures 40 and 42, which represent the condition in the ventral region, with figures 41 and 43, which are sections through the more dorsal part. There is, in fact, a continuous pulmohepatic space 4, 4°, 4, 4°, on either side closed posteriorly by the post-hepatic septum (figs. 40, 42, and 43, ft, ft and fig. 41 /3-f y & /3). I would compare the imperfect partition (d.a°, d.a°, figs. 40 & 42) to the ventral portion of the avian diaphragm. The septum behind the liver appears to m e to be homologous with the post-hepatic septum of Tupinambis, or with the ventral or omental part of the post-hepatic septum of the bird. And perhaps the most dorsal part near the postero-dorsal extremity of the lung and liver may represent the dorsal element (oblique abdominal septum of the bird). But besides these lateral pulmo-hepatic cavities, there are, anterior to the post-hepatic septum, two smaller sacs on either side in the region of the liver, which must now be described. In fig. 42 we see on either side of the median ventral ligament (m) a closed peritoneal sac (1, 1') containing a portion of the liver-lobe of its side. These sacs I would roughly compare to the large ventral liver sacs in the bird (figs. 29 et var. 1, ]'). However, the lateral boundaries (Lob, l.ob) of these spaces in the Crocodile do not seem to correspond exactly to any membranes in the bird, but to the oblique ligaments of the liver described above (p. 466) in the Lacertilia, as apparently complementary to the pulmohepatic ligaments which are represented in all three groups. The relations of these spaces (1, V) and ligaments (l.ob, l.ob) are further illustrated in the transverse sections (figs. 37 & 38) and in the longitudinal section (fig. 39). The second pair of cavities in the region of the liver are specially worthy of consideration. These are the cavities 2 & 2' on the right and left sides respectively in the longitudinal sections (figs. 40 & 43, & 41 right side) and in the transverse sections (figs. 37 & 38). I regard them as comparable to the pulmohepatic recesses of the bird. That on the left side seems to be entirely closed, and since it lies between the liver and the alimentary canal it is not bounded antero-dorsally by the lung and mediastinal tissue, and it can only be compared with the posterior and more median portion of the corresponding recess in the bird. The space on the right side, however, much resembles the corresponding space in the bird or lizard in its relations to the liver and lung; it is bounded on the outside by the pulmohepatic ligament (figs. 37, 40, 41, 43, a), which, as in the lizard or bird, passes postero-dorsally into the membranous tract (y, fig. 38) that is continuous with the posterior extremity of the pulmonary and mediastinal tissue (oblique abdominal septum of bird). On the right side I found, in some of the young specimens examined, a passage between the pulmohepatic recess and the |