. Elements of comparative zoology. Zoology. FIG. 41.—Quahog (Venus mercenaria), with foot and siphons extended. then strong retractor muscles to draw them back are present. All of these muscles—adductors, retractors, etc. -leave their impress on the shell, so that the student, with the shell alone, may know of some •/ of the structures of the soft parts (fig. 42). Water is drawn into the mantle-cavity by means. of very minute hair-like FlG- 42.—inside of bivalve shell ing muscular impressions of a, an- StrUCtlireS (Cilia} Which terior adductor; p, posterior adduc- tor; s, siphonal muscle. cove
. Elements of comparative zoology. Zoology. FIG. 41.—Quahog (Venus mercenaria), with foot and siphons extended. then strong retractor muscles to draw them back are present. All of these muscles—adductors, retractors, etc. -leave their impress on the shell, so that the student, with the shell alone, may know of some •/ of the structures of the soft parts (fig. 42). Water is drawn into the mantle-cavity by means. of very minute hair-like FlG- 42.—inside of bivalve shell ing muscular impressions of a, an- StrUCtlireS (Cilia} Which terior adductor; p, posterior adduc- tor; s, siphonal muscle. cover the gills and other parts. These cilia are in constant motion,* and thus currents of water are produced, flowing always in one * The teacher should demonstrate this ciliary action under the compound microscope,. 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 Kingsley, J. S. (John Sterling), 1854-1929. New York, H. Holt and Company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1904
