Elementary textbook of economic zoology and entomology . elementarytextbo00kell Year: [c1915] 232 ECONOMIC ZOOLOGY AND ENTOMOLOGY pets so common on the rocks everywhere, the helmet-shells from which cameos are cut, and hosts of others all belong to this group. The large sea-snails and the much smaller but more numerous drills (family Muricidce) are often of serious economic importance. The sea-snails bore holes by means of their roughened tongue-like organ, the radula, and an acid salivary secretion through even the thickest-shelled clams, and suck out the soft body of the victim. The oyster-
Elementary textbook of economic zoology and entomology . elementarytextbo00kell Year: [c1915] 232 ECONOMIC ZOOLOGY AND ENTOMOLOGY pets so common on the rocks everywhere, the helmet-shells from which cameos are cut, and hosts of others all belong to this group. The large sea-snails and the much smaller but more numerous drills (family Muricidce) are often of serious economic importance. The sea-snails bore holes by means of their roughened tongue-like organ, the radula, and an acid salivary secretion through even the thickest-shelled clams, and suck out the soft body of the victim. The oyster-drills, of the genus Urosalpinx and of other genera, drill holes through the oyster shells in the same manner, and as they often occur in great numbers on the oyster beds they may destroy many oysters. Some of them have a habit of collecting in great masses at their breeding season, and are sometimes gathered FIG. 107. — Two kinds of oyster-drills; large one, Polynices Gould; small one, Thais lamcllosa. (Reduced.) and used for food. Many Muricida when crushed exude a reddish-purple fluid which in olden times was used as a dye famous under the name of Tyrian purple. Abalones, or ear-shells, which are particularly abundant along certain parts of the California sea-coast, are of interest because of their economic importance. The animal lives attached to a rock by a great muscle which fills most of the firm ear-shaped shell that covers it. The outer side of the shell is rough and dull-colored but the inner surface is smooth
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