| OCR Text |
Show 1904.] CIRCULATORY SYSTEM IX T H E OPHIDIA. 345 series supplies the right side and also sends back a large branch to the liver. The alternation is kept up with perfect regularity until the ninth and largest of the series, which, immediately after its origin from the aorta, divides into two vessels, each of which supplies one only of the longitudinal gastric trunks. The same is the case with the tenth vessel, which is also concerned with the blood-supply of the gall-bladder. The eleventh arises opposite the gall-bladder and runs over it. Immediately after the gall-bladder arises the very large mesenteric vein, which is really almost as thick as the aorta. It runs down the intestine, giving off branches to the same. The first branch is much the largest and supplies the gall-bladder, spleen, and pancreas. I could not find any gastric branch to this artery and feel assured that if such a branch exists, which might I admit be expected, it is not large. It looks to m e very much, in fact, as if the superior mesenteric artery in this snake had retained its original derivation from two separate trunks, one gastric and one intestinal, and that therefore the last gastric which crosses the gall-bladder really belongs to it. Ovarian and Oviduccd Arteries.-As is usual in the Ophidia, the arteries to the gonads come between the superior mesenteric and the remaining arteries of the alimentary tract. The first of this series of arteries is the anterior ovarian artery, which opens into a longitudinal artery running down the gonad. Separated from this by five intercostal arteries is a much larger vessel which supplies the oviduct belonging to that ovary and the fat-bodies ; its mode of distribution to these two organs is rather curious. It divides almost immediately into trunks, roughly equisized, which pursue a tortuous course at right angles to each other, the one anteriorly and the other posteriorly. The former reaches the oviduct and forms a longitudinal vessel running along the oviduct and giving off numerous branches to the lobules of the fat-body. The posterior branch seems to be entirely concerned with the blood-supply of the fat-body; it forms a longitudinal trunk and gives off numerous branches right and left. Very close to this trunk and behind it arises the second ovarian artery. The oviducal artery lies much further back and is separated from the ovarian artery by two intestinal arteries and two renals belonging to the anterior kidney. Intestinal Arteries.-I observed only two of these, but there may be others posteriorly, where the injection had failed. It is noteworthy that in this species, unlike what is found in some others*, the first intestinal artery, which we may term the inferior mesenteric, immediately follows the gonad arteries and precedes the renal. The rectal artery lies next to the second renal artery of the anterior kidney. Renal Arteries.-Here, again, I a m unable to give full details. I can only say that two renal arteries of the anterior kidney arise * K. g., Naia tripudians. |
