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Show 1904.] CIRCULATORY SYSTEM IX THE OPHIDIA. 8Ef5 Genital Arteries.-It is remarkable that both the ovary and testes, in spite of the disproportion of their size, are each of them furnished with a single artery only; that is to say, of course, there is a separate artery to each ovary and to each testis. The artery supplying the anterior testis is the first artery which springs from the aorta after the superior mesenteric; it is closely accompanied by a parietal portal vein. Then follow six arteries which supply the vas deferens and the suprarenal. But of these six, the first and the last but one are mainly (perhaps really exclusively) fat-body arteries. After them arises the artery of the second, posterior, testis ; this is given off close to the inferior mesenteric. I a m uncertain how many arteries supply the vas deferens of this testis. Three parietal portals lie among these vas deferens arteries. The ovarian and oviducal arteries are very similar in their arrangement. The artery of the anteriorly-situated ovary is also the first artery to spring from the aorta after the origin of the superior mesenteric, but it is placed farther forwards than in the case of the testicular artery. It is closely accompanied by a branch of the portal; it is followed by two oviducal arteries, of which the second gives off a large branch to the fat-body. Near to each of them is a parietal branch of the portal. Then comes the ovarian artery of the posterior ovary. This is followed by two oviducal arteries; after which comes the second fat-body artery. This is again followed by two oviducal arteries, between which lies a parietal portal vein. All these arteries lie in front of the inferior mesenteric, which is the next artery to follow. OPHIOPHAGUS BUXGARUS. In this species the much shorter left aortic arch gives off five quite slender vessels to the oesophagus before it joins the right aorta. The latter, at the point of junction, is about one-third of the diameter of the former. The right aorta gives off four intercostals before it fuses with the left arch. These intercostals agree with the entire series in perforating the body-wall in the middle line. This state of affairs is apparently without exception, and is thus characteristic of the species, as it is of Lctchesis gramineus. There are about 80 of these arteries * from the junction of the aorta to the end of the body; they are, as usual, given off at irregular intervals, sometimes closer, sometimes further apart. Below the muscles each artery divides at once into a right and left branch. The anterior vertebral runs up the neck to within an inch of the head, giving off median intercostals; these are very nearly one to each successive vertebra, but the arrangement is not quite regular. I counted 24 arteries supplying the oesophagus and liver, * I cannot be certain to two or three, as the injection was deficient posteriorly. o •>* |
