. Zoology : for students and general readers . Zoology. Fig. \^2.— Vnio com^latmtus, partly buried In the sand, the siphonal openings above the level of the river-bottom.—After Morse. of the siphon. Through the visceral mass passes a curious slender cartilaginous rod, whose use is unknown, unless it be to support the voluminous viscera. The gills or branchiaB are four large, broad, leaf-like folds of the mantle, two on a side, hanging down and covering each side of the visceral mass (Fig. 161, D, g). The heart (Fig. 163) is contained in a deh- cate sac, called the pericardium, and is situ- ate
. Zoology : for students and general readers . Zoology. Fig. \^2.— Vnio com^latmtus, partly buried In the sand, the siphonal openings above the level of the river-bottom.—After Morse. of the siphon. Through the visceral mass passes a curious slender cartilaginous rod, whose use is unknown, unless it be to support the voluminous viscera. The gills or branchiaB are four large, broad, leaf-like folds of the mantle, two on a side, hanging down and covering each side of the visceral mass (Fig. 161, D, g). The heart (Fig. 163) is contained in a deh- cate sac, called the pericardium, and is situ- ated immediately under the hinge ; it consists of a ventricle and two auricles ; the former is easily recognized by the passage through it of the intestine (Fig. 161, D, v); usually colored Fig dark, and by its pulsations. The two wing- ?entrideT"'. a^' ^'^^ auricles are broad, somewhat trapezoidal "fi7e' i.'ATte°r in foi™- J^st behind the ventricle is the so- Morsl.' called "aortic ; The arterial system is quite complicated, as is the system of venous sinuses, which can be best studied in carefully injected specimens. At the base of the gills, however, is the pair of large collective branchial veins. The kidney, or "organ of Bojanus," is a large dusky glandular mass (Fig. 164, 4) lying below but next. 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 the original Packard, A. S. (Alpheus Spring), 1839-1905. New York : Henry Holt
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1879
