| OCR Text |
Show 1904.] CIRCULATORY SYSTEM IX THE OTHIDIA. 341 portal trunk. In both specimens a single intercostal portal arises near to the penultimate artery of the series. It is plain, therefore, that there is no serious discrepancy of a real character between the gastric arteries in the two individuals. Whether such differences as these are sexual or not I do not know. Between the superior and inferior mesenteric arteries lie the ovarian arteries. The first seven of these, of varying sizes, supply the fully developed (right) ovary and oviduct. Then follow two arising from the opposite side of the body, which go to the left ovary; finally, a single artery is again concerned with the right oviduct, after which rises the inferior mesenteric. Branches of these genital arteries reach the fat-bodies; but, so far as I can make out, no special arteries supply those organs. There is one important rectal artery which arises shortly after the inferior mesenteric. Between these two arteries arises the first of the renal series, to be referred to immediately. Besides this important rectal artery I found five smaller vessels. The renal arteries are four to the right, and three to the left kidney. Intercostal Portal Branches.-These are few in number, and I have only mapped them accurately in one (the female) specimen. I counted five altogether, of which four belong to the first series of intercostal arteries. These veins, like the arteries, vary as to which side of the dorsal median line they enter or rather emerge from the parietes. .The first two emerge on the left side, the last three on the right. Furthermore, these vessels differ among themselves as to whether they pass below or above the aorta. This position is in absolute correspondence with the point of emergence from the parietes-that is to say, the first two veins pass ventrally of the aorta, the last three dorsally. ZAMENIS GEMOXEXSIS. The anterior vertebral artery is much more extensive in this species than in Z. flagelliformis. It extends more than halfway along the neck before becoming lost by plunging into the parietes. In this space a large number of intercostals are given off from the main trunk. I counted 9 in one specimen and 6 in the other; in the latter, however, the vertebral artery itself was not so extensive, only reaching halfway up the neck. In both specimens the right aortic arch gave off three or four intercostals before uniting with its fellow to form the dorsal aorta. It must be noticed that here, as in the last species, these cervical intercostals enter the parietes exactly in the middle line. The intercostals which arise after the junction of the aorta? enter to the parietes either to the left or to the right of the dorsal middle line, or they are paired. The first 20 in one specimen and the first 14 in the other are given off on the left side, and enter the parietes on that side. The difference in number is not great-in one specimen 30, in the other 34 intercostals lie in front of the superior mesenteric. There are 15 intercostals up to the end of the liver in one specimen, 18 in the other. |
