. Animal physiology. Physiology, Comparative; Physiology, Comparative. 230 CIRCULATION IN MOLLUSCA. lation that prevails among the Mollusca in general, and that which we have seen in the class of Fishes. The auricle and ventricle of the heart are separated from each other; and whilst the latter remains in the position just described, the auricle occupies the place which the whole heart possesses in the class above. The course of the blood in these animals is shown in Fig. 134; where c represents the ventricle or systemic heart, from which arises the aorta a, a, as, av, that supplies the body w
. Animal physiology. Physiology, Comparative; Physiology, Comparative. 230 CIRCULATION IN MOLLUSCA. lation that prevails among the Mollusca in general, and that which we have seen in the class of Fishes. The auricle and ventricle of the heart are separated from each other; and whilst the latter remains in the position just described, the auricle occupies the place which the whole heart possesses in the class above. The course of the blood in these animals is shown in Fig. 134; where c represents the ventricle or systemic heart, from which arises the aorta a, a, as, av, that supplies the body with arterial blood. The venous blood is returned through the great vein v c, covered with a curious spongy mass c s, the use of which is not known; this also receives the blood from the intestinal veins v v; and it divides into two trunks which convey the blood to the gills or branchiae (br and br'), where it undergoes aeration. On each of these trunks is an enlargement, c b, which has the power of contracting and dilating, and thus of assisting the transmission of the blood through the arteries of the gills, ab. The blood is returned to the ventricle by the branchial veins, v b0 on each of which there is another dilatation, bu, which might be regarded as analogous to the auricle of the other Mol- lusca, but is not muscular. Thus in the Cuttle-fish, the blood receives an impulse from the systemic heart, when it is trans- mitted into the main artery; and when it returns by the sys- temic veins, it receives another impulse from the branchial hearts, before it passes through the gills;—an arrangement obviously analogous to that which we meet with in the highest Vertebrata. 292. In the Crab and Lobster, and other animals of the class. Fig 135.—Circulating Apparatus of Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble th
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