Cardium (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 edition. Excerpt: ...membranous partition, beginning at the dorsal surface of this neck, extends backwards and downwards across its cavity, embracing the rectum, and ends so that its free edge lies near the ventral surface. This must form a valve preventing the reflux of blood into the ventricle from the posterior part of the body. Behind this valve the tube expands forming a "bulbus arteriosus" (B.a., fig. 30) with thin muscular walls. This terminates in two lateral branches, the right and left posterior pallial arteries which diverge from each other and pass backwards beneath the posterior adductor. Here their walls become very illdefined and communicate freely with a system of lacunae between the bundles of the muscle. The arteries, which ar-e now difficult to trace, reach the mantle margin and terminate in the sinuses there and in the walls of the siphons. Anteriorly the ventricle passes into a single median vessel with well defined walls, the anterior aorta (A0., fig. 30); this pierces the posterior wall of the viscero-pedal mass, and travels along in the dorsal region of the latter, giving ofif, in its course, small vessels to the digestive gland. Near " Grobhen, Dr. C. Die Pericardialdriise der Laniellibrancliiaten. Arbeit. Z001. Inst. Wien. Bd. VII. 1888. the anterior margin of the viscero-pedal mass the aorta bifurcates; one vessel runs straight forward over the anterior adductor to the mantle lobes, forming the anterior pallial artery (Art.p.a.), the other passes straight downwards as the viscero-pedal artery. In its course this gives off a vessel from its anterior side which soon bifurcates, forming the right and left labial arteries (A.lab.). Still further down a large vessel is given off from the posterior side, the visceral...