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Show There are many differences in detail between the venous system of this lizard and that of other genera. Vena cava 'posterior.-It is interesting to note that Gerrhosaurus agrees with Tiliqua in that the left vena cava posterior is very much thinner than the stout right vein. This is another of those numerous though individually perhaps small points of likeness between the genus whose anatomy is dealt with in the present communication and the Scincidse. As in Tiliqua also *, the left cava or vena renalis revehens lies to the left side of the mesorectum and the right vein to the right side of that mesentery. The left vena revehens is large where it receives the three or four veins arranged in a fan-like fashion from the left ovary ; behind this point it dwindles immediately but can be easily traced to the kidney, where it becomes enlarged at its jnnction with the right vena renalis revehens. The left vena renalis revehens receives two intercostal veins before the ovarian veins join it, and on the right side also I observed two intercostals. I could only observe one, and that a slender, oviducal vein joining the left vena renalis revehens. I feel convinced, however, that no veins from the oviducts join the afferent renal veins, as is often the case in Lizards. The reason for this in the present species may be that the kidneys are unusually far back. Afferent Renal Veins.- The caudal vein reaches the kidneys as an undivided vein. It runs between them and receives a cloacal vein before dividing. Immediately after division each half receives another cloacal vein. The cloacal artery runs exactly at the point of division between the two afferent renals. At about the end of the first third of the kidney each renal afferent vein turns at light angles and runs superficially over the kidney, giving off a large branch to the kidney itself at about the middle of the transverse diameter of that organ. There is no sign of any forward continuation of the renal afferent vein beyond the anterior border of the kidney such as occurs in Chamceleon and Pygopus f. Where the renal afferent vein reaches the border of the hind leg it receives three veins, two from the hind limb and one from the median dorsal parietes. It there runs directly forwards parallel with the kidney, and on a level with the anterior end of that gland receives the femoral vein, and a small parietal on the opposite side which crosses the epigastric artery. The vein then continues its straight course forward, and before bending inwards and downwards to follow closely the inner margin of the fat-body gives off a short forwardly directed branch, which appears to me to be the equivalent of the lateral abdominal vein of other Lizards. Its shortness in Gerrhosaurus contrasts with its length in Tiliqua. Hepatic Portal Veins.-The mode of entrance of the conjoined intestinal portal and anterior abdominal and of the epigastric vein * See Beddard, P. Z. S. 1904, vol. i. p. 445, fig. 93. 266 ON THE ANATOMY OF THE YELLOW-THROATED LIZARD. [June 6, |