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Show 1904.] CIRCULATORY SYSTEM IX THE OPHIDIA. 369 number. There are, for instance, twenty in Coluber melanoleucus, which has not, I m a y remark, a specially long liver. The arteria epiploica, the longitudinal artery of the fat-body, is fed from several distinct sources. Arteries arise independently from the aorta, from the spermatic arteries, from the oviducal (arterice uterince in Bronn's ' Thier-Reich'), from the superior and inferior mesenteric, from the renal and gastric arteries. But I have not found all these origins to coexist in the same species. It is clear, from the facts at present known, that the rule among the Ophidia is that each gonad has but a single spermatic artery. The extraordinary length of the testes in Python spilotes may account for their richer blood-supply. It is noteworthy, moreover, that the artery or arteries generally reach the testes at their posterior extremity. On the other hand, the ducts of the gonads, whether male or female, commonly receive their blood-supply from a number of separate branches of the aorta. Exceptionally (as in Tropidonotus fasciatus) both ovary and oviduct may be supplied by branches of the superior mesenteric, in addition to their own proper arteries. And this is the case with the testes in Python spilotes. The renal arteries appear to vary from a single one to each kidney (Python spilotes) to eight such arteries in Coronella catenifer. The close association of the arterial supply of gonad and kidney in Ophiophagus bungarus (see p. 357) is quite exceptional. Little attention seems to have been paid to the epigastric artery, which, however, exists and has been chiefly studied by m e in Ophiophagus. It is a continuous trunk running from end to end of the body in close association with the anterior abdominal vein, and is fed by the carotid anteriorly and the fat-body artery posteriorly. As to the venous system, I may chiefly remark upon the epigastric vein, which I have most particularly studied in Ophiophagus. It extends along the lower body-wall and sends branches to the shorter lobe of the liver along its whole length. The portal system of the dorsal parietes appears to exist in all Snakes. The trunks which arise from the parietes appear never to issue from the muscular walls exactly in the middle line; they are always to the right or left of that line, and in this they differ from the intercostal arteries. There is always, or nearly always, a specially large trunk in the immediate neighbourhood of the superior mesenteric artery. It is remarkable that the intercostal veins of the trunk should be connected with the portal systems, while those of the "thorax" and neck open into vertebral veins. I a m able to confirm and extend Gratiolet's discovery* of a suprarenal portal system, which appears to be universally present. I have given above a number of detailed figures showing the number and position of these veins (pp. 358, 364, &c.) in several Snakes. * " Note sur le systeme veineux des Reptiles," Journ. de l'lnst. xxi. 1853, p. 60. PROC. ZOOL. Soc-1904, VOL. I. No. XXIV. 24 |