. Elements of zoölogy. Zoology. 6o MOLLUSC A. author twenty years ago, has now disappeared, having crumbled away under their tunneling. Hulls that appear solid may be crushed by the hand—completely honey-combed. In 1731 they nearly destroyed the piles in Holland, threatening the country with destruction. They attack floating wood, and so are carried all over the world. Docks at Tortugas, Fla., were rendered unsafe in twelve months. Palmetto is the most successful resistant. Watering-pot Shells {Aspergillum).—In these shells the two valves are imbedded in the lower part of the tube, the beaks o
. Elements of zoölogy. Zoology. 6o MOLLUSC A. author twenty years ago, has now disappeared, having crumbled away under their tunneling. Hulls that appear solid may be crushed by the hand—completely honey-combed. In 1731 they nearly destroyed the piles in Holland, threatening the country with destruction. They attack floating wood, and so are carried all over the world. Docks at Tortugas, Fla., were rendered unsafe in twelve months. Palmetto is the most successful resistant. Watering-pot Shells {Aspergillum).—In these shells the two valves are imbedded in the lower part of the tube, the beaks only being visible externally. The tube which incloses the siphon ends in shelly expansions or ruffles; at the other or anterior end it is club-shaped, and cov- ered by a disk like the nose or sprinkler of a watering- pot, and perforated with numerous holes in exactly the same way. They are found in tropical countries, buried in the mud or sand, the ruffled end containing the siphon exposed. SINGLE-SHELLED MOL- LUSKS. Class II.—Snails, etc. {Gasteropoda, belly- footed). General Characteristics. —Mollusks that secrete a single shell. They have ears and eyes upon a dis- tinct head. The foot is now a flat, creeping disk. Fig. 63.—The interior of a univalve {Periwinkle), f, foot; m, muscle for drawing back into the shell; g, spittle glands; the glands for giving out slime are near the anus tube; t/i, throat leading to s, stomach ; r, tooth-bearer rolled up; br, branchiae or breathing- gills, which, when the mantle is folded back in its place, lie over the throat; a, anus; o, ovary car- rying 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 company
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
