| OCR Text |
Show 1906.] ANATOMY OF CENTROPHORUS CALCEUS. 87 7 The visceral arteries arising from the dorsal aorta are three in number-the cceliac, the lieno-mesenteric, and the posterior mesenteric. The coeliac, as indicated in PI. LVII. fig. 3, supplies the liver, stomach, and duodenum. The lieno-mesenteric, about four inches from its origin, divides into the splenic and anterior mesenteric; the former runs to the middle of the larger spleen where, after giving off* small branches to this organ, it divides into two vessels, one of which runs to the cul-de-sac of the pylorus and the other to the posterior extremity of the outer lobe of the pancreas; the latter runs directly to the anterior portion of the spiral-valve intestine. The posterior mesenteric supplies the rectal gland as usual. The oviducts are each supplied in the region of the oviducal gland by three arteries arising from the dorsal aorta at about the level of the eleventh or twelfth vertebra, as shown in PI. LX1I. fig. 19. The posterior cardinal sinuses are large in diameter and lie on each side of the vertebral column ; they arise by the bifurcation of the caudal vein about three inches in front of the anterior extremities ot the pelvic fins. There is no " renal-portal system " -the slender kidneys lying externally to the sinuses. The posterior cardinals suddenly diverge anteriorly to open as usual into the Cuvierian sinuses, the small lateral veins opening into the posterior cardinals just before. The anterior cardinal sinuses, subclavian arch, brachial veins, and internal jugulars exist as usual. The hepatic-portal vein (which has several conspicuous factors in connection with the spleens, pancreas, and spiral-valve intestine) is large and runs, as before described, in the same muscular band as the bile-duct and goes first to the right lobe of the liver, as shown in fig. 3 (PI. LVII.). I neglected to ascertain its further course anteriorly, including its relation to the left lobe of the liver. The hepatic veins enter the sinus venosus by two large apertures situated some distance apart (PI. LVIII. fig. 4). According to Neuville 111 (who has dissected Centropliorus granulosus and C. squamosus), the genus Centropliorus is characterised by the absence of hepatic sinuses : " les veines sus-hepatiques forment des troncs qui, au lieu de confluer pour former un sinus commun, restent completement independants et debouchent directement dans les canaux de Cuvier, apres avoii subi un renflement presque insensible." Also, according to Neuville, Centropliorus, with Selachians generally 24, possesses an intra-intestinal artery and vein which course along the margin of the spiral valve, the latter of course forming a factor of the hepatic-portal vein. The appearance of the hepatic apertures in the sinus venosus of C. calceus is confirmatory of Neuville's former statement. Each of the oviducts has a conspicuous vein running along its outer edge, which I presume enters the posterior cardinal of the corresponding side anteriorly. A small vessel, apparently a vein (PI. LXT. fig. 16, B.V.), ran 24 " Sur les Vaisseux intra-intestinaux des Selaciens." Bull. Mus. Paris, 1897 (7). |
