. Animal forms; a second book of zoology. Zoology. MOLLUSKS 81 striking peculiarity is in the univalve shell, with numerous whorls, into which the animal may at any time withdraw completely. Ordinarily this is carried on the back of the spindle-shaped body, which is fashioned beneath into a great. Fiu. 48.—The slug {Ariolimax) and common snail {Helix). From life. flat sole or creeping surface that bears on its forward bor- der a wide opening through which mucus is continually issuing to enable the snail to slip along more readily. Slime also exudes on other points on the surface of the body an
. Animal forms; a second book of zoology. Zoology. MOLLUSKS 81 striking peculiarity is in the univalve shell, with numerous whorls, into which the animal may at any time withdraw completely. Ordinarily this is carried on the back of the spindle-shaped body, which is fashioned beneath into a great. Fiu. 48.—The slug {Ariolimax) and common snail {Helix). From life. flat sole or creeping surface that bears on its forward bor- der a wide opening through which mucus is continually issuing to enable the snail to slip along more readily. Slime also exudes on other points on the surface of the body and affords a valuable protection against excessive heat and drought. Unlike the clams, the forward end of the body is devel- oped into a well-marked head bearing the mouth and a complicated mechanism for gathering and masticating food, together with two pairs of tentacles, one of which carries the eyes. On the right side of the animal, some distance behind the head, is the opening of the little sac-like mantle cavity (Fig. 48) which contains the respiratory organs, and into which the alimentary canal and the kidneys pour their wastes. The relation of these organs to the mantle cavity is the same as in the clams, though the cavities differ much in size and position. 82. Other snails. The shell.—Extending our acquaint- ance to other species of snails, we find the same general plan of body, although somewhat obscured at times by. 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 Jordan, David Starr, 1851-1931; Heath, Harold, 1868- [from old catalog] joint author. New York, D. Appleton and company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
