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Show 14 MR. F. E. BEDDARD OX THE [May 3, springs from the ventral surface of the aorta, just in front of a pair of intercostals; it crosses one of these intercostals, but blends with that artery at the point of crossing. The next visceral artery to arise from the aorta is the oviducal of each side ; these are strictly symmetrical, and each arises, not independently from the aorta, but from the intercostal of its own side. Next arises the cfecocolic artery, which is crossed shortly after its origin in the usual way * by the subsequently arising coeliac trunk, which is, it will be observed, a single trunk. Upon this trunk follows the ovarian and suprarenals, of which one arises independently from the aorta and the other from the intercostal of its own side. Then occurs a long gap, the next trunk to arise being the right renal, which springs from an intercostal. So, too, and a little further back, does another oviducal artery. On the whole, therefore, the most remarkable feature of the arterial system of Pygopus appears to be the origin of many of the arterial branches from the intercostals instead of directly from the aorta. Noteworthy, too, is the large number of gastric arteries, which is perhaps to be looked upon as associated with the snake-like form of this lizard. There being only rudimentary hind limbs, the system of the vence renales advehentes is much simplified (Text-fig. 4, p. 15). The caudal vein divides into two branches, one for each kidney. Each vein soon divides into three branches, i. e. the anterior abdominal, the lateral abdominal, and the afferent renal. This last vein, in the case of the right kidney, runs over the gland, giving off branches, nearly to its anterior extremity. On the left side the termination of this vein was particularly interesting, as showing a distinct resemblance to the Chamaeleon. As in the latter reptile, the vein does not end upon the kidney, but is prolonged beyond it for some little distance, and is lost in the parietes to the left of the middle line. It clearly represents the posterior vertebral vein, and its presence on one side of the body only is, it will be remembered, occasionally paralleled in Chamaeleon. At about the middle of the kidney a vein from the oviduct (on each side) reaches the afferent renal. The efferent renals arise at first as a single trunk very near to the posterior end of the kidneys, and of course between them. This trunk divides into two before reaching the middle of the kidneys. The left efferent renal receives first of all a vein from the posterior region of the left ovary, and then passes in close contact to, receiving branches from, the left suprarenal. It forms the right efferent renal just in front of the left and just behind the right suprarenal. Before their junction the right efferent renal receives a branch from the posterior region of the right ovary. Into the vena cava thus formed by the union of the two efferent renals opens first of all, and at about the middle of the right suprarenal, the anterior left ovarian vein, into which opens * See Hochstetter's account of visceral arteries in Lacertilia in Morph. Jahrb vol. xxvi. p. 213. |