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Show 484 MR. P. E. BEDDARD ON THE [Nov. 28, Between the liver and the stomach runs a forward extension of the portal vein, which dies away anteriorly but nearly reaches the forward extremity of the liver. At fh'st the dorsal parieto-hepatic vessels, where the right lobe of the liver is prolonged beyond the gall-bladder, open directly into the intra-hepatic venous system. But further forward, where the two lobes of the liver come into continuity and the two dorsal hepatic ligaments fuse, the parieto-hepatic portal veins open into (or at least very close to) the forward extension of the portal vein already referred to. It is only in this region that gastro-hepatic vessels occur. The left gastro-hepatic ligament carries no gastro-hepatic vessels, that I could see, in that part where it is free from the right ligament. The vessels, in fact, are first visible about 40 mm. from the anterior end of the liver. They open into the longitudinal portal vessel like the dorsal parieto-hepatic veins. It is important to notice the likeness which the arrangement of these veins in Amphisbcena bears to the similar arrangement of the same veins in Snakes on the one hand and in Hatteria on the other. In Lacertilia, as a rule, the gastro-hepatic veins bringing blood from the stomach and oesophagus to the liver enter the latter organ separately, or at most one or two blend together before opening into the blood-sinuses of the liver. In Hatteria, as I have already pointed out *, there is a collecting-vein, which is a prolongation forward of the portal vein, that is the conjoined portal and anterior abdominal, which runs in the gastro-hepatic ligament on the left side of the body and receives on the one hand veins from the stomach, while on the other side it gives off veins to the liver. There is, however, in Hatteria, no further resemblance to the conditions which obtain in Amphisbcena. In Snakes there is the further likeness in that, while there is the same forward prolongation of the portal vein forwards between the liver and the stomach, this vein not only receives branches from the stomach which it transmits to the liver from the opposite side, but it is also in connection with the venous system of the body-wall by means of the dorsal parieto-hepatic veins, which thus come, as in Amphisbcena, into close relations with the gastro-hepatic veins. The important point of likeness between all three types is, as it appears to me, the extension forwards of the portal up to or nearly up to the anterior extremity of the liver. The close association in Snakes and in Amphisbcena of the dorsal parieto-hepatic vessels with branches from the stomach to the liver seems to me to be dependent merely upon the narrow form of the body and of the liver, and the consequent necessity of packing everything in a narrow space. As it is so markedly the rule for the portal to enter the liver at its hinder border in the Lacertilia, these two divergences from that normal condition cannot but attract attention, especially as they show a likeness to the admittedly nearly * Above, p. 464. |
