. Elements of zoölogy. Zoology. 54 MOLL USCA. etc. The eyes, when present, are in the borders of the mantle, and often resemble gems. The foot is a muscular organ that projects from the mantle nearly opposite the siphon, by which the animal leaps, moves, or glues itself to the rock, as the case may be. The ear is in the foot—a transparent sac containing a clear fluid in which floats a glassy globule. BIVALVES WITHOUT SIPHONS. Oysters {Ostreidce).—The oyster is found in great beds upon the coasts of many countries. About 425 different living species are known, and over 1,400 fossil, some of the
. Elements of zoölogy. Zoology. 54 MOLL USCA. etc. The eyes, when present, are in the borders of the mantle, and often resemble gems. The foot is a muscular organ that projects from the mantle nearly opposite the siphon, by which the animal leaps, moves, or glues itself to the rock, as the case may be. The ear is in the foot—a transparent sac containing a clear fluid in which floats a glassy globule. BIVALVES WITHOUT SIPHONS. Oysters {Ostreidce).—The oyster is found in great beds upon the coasts of many countries. About 425 different living species are known, and over 1,400 fossil, some of the latter being of gigantic size. A single oyster will de- posit during July and September over 1,000,000 yellow eggs. At first they remain in the gills, but finally leave the parent, and, after swimming about for a while by means of cilia, during which their numbers are greatly dimin- ished, they finally settle upon the bottom, and in five or six weeks are as large as a grain of corn, three years, how- ever, being required to attain full growth. They generally lie upon their sides, and are often inhabited by one or more small crabs (Pimwtheres). Value.—Seven hundred and sixty-five million oysters are handled yearly in New York alone, representing a capital of $1,577,000, the industry giving employment to thousands. Comb Shells (Pectens).—The Pectens are generally round, with radiating ribs from the valves, and are noted for their loco- motive powers, and the luster and brilliancy of their gem-like eyes that dot the mantle. They Fig. swimming, by violently have also numbers of opening and closing its valves. filaments that extend. 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 Holder, Charles Frederick, 1851-1915; Holder, Joseph Bassett, 1824-1888, joint author. New York : D. Appleton and
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
