. Elements of zoölogy. Zoology. 52 MOLLUSC A. of dead shells several scars are seen, some oval and others mere lines ; the former are the marks of the adductor mus- cles, ey e, that move the valves, opening and shutting them. Near by are smaller scars, showing the position of the pedal muscles that moved the foot. The line running par- allel with the margin of the shell is called the pallial line, /, and shows where the mantle was attached to the Fig. 54.—Bivalve shell, a, beak ; k, base ; b, b, hinges ; c, d, d, principal teeth ; //, ligament; e, e, adductor muscles ; /, lines of grow
. Elements of zoölogy. Zoology. 52 MOLLUSC A. of dead shells several scars are seen, some oval and others mere lines ; the former are the marks of the adductor mus- cles, ey e, that move the valves, opening and shutting them. Near by are smaller scars, showing the position of the pedal muscles that moved the foot. The line running par- allel with the margin of the shell is called the pallial line, /, and shows where the mantle was attached to the Fig. 54.—Bivalve shell, a, beak ; k, base ; b, b, hinges ; c, d, d, principal teeth ; //, ligament; e, e, adductor muscles ; /, lines of growth ; /", pal- lial line. Fig. 55.—Mollusk, without siphon. S, shell; m, lower half of man- tle; m', a piece of the upper half; g, breathing-gills ; //, heart; Iv, liver ; Ip, lips; o, opening of mouth ; a, anus, where refuse is thrown out; ms, muscle hold- ing shells together; c, elastic cushion forcing them apart. Internal Organs.—Opening the valves, we note the two leaves of the mantle, or body-wall, whose function is to secrete and repair the shell. Removing these, we see the gills (Fig. 55, g) or branchiae that are open in front and joined at the back. They appear made up of minute rods covered by a maze of veins, and are provided with cilia. The siphon (Fig. 56, s), or so-called blackhead, when present, projects through the mantle, and in the clam is capable of great distention. It is divided into. 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
