. Elements of comparative zoology. Zoology. 278 SYSTEMATIC ZOOLOGY. gradually the muscle of the oyster becomes fatigued, until at last it can no longer hold the shell closed. Then the starfish protrudes its stomach from the mouth, envelops the flesh of the oyster with it, and thus digests the oyster out- side of the body. The retractor muscles are to draw the stomach back after a meal. This method of external eat- ing explains the frequent degeneration or absence of intestine and anus (p. 277). Class II.—OPHIUROIDEA (Brittle-stars). The brittle-stars, or serpent-stars as they are frequently ca
. Elements of comparative zoology. Zoology. 278 SYSTEMATIC ZOOLOGY. gradually the muscle of the oyster becomes fatigued, until at last it can no longer hold the shell closed. Then the starfish protrudes its stomach from the mouth, envelops the flesh of the oyster with it, and thus digests the oyster out- side of the body. The retractor muscles are to draw the stomach back after a meal. This method of external eat- ing explains the frequent degeneration or absence of intestine and anus (p. 277). Class II.—OPHIUROIDEA (Brittle-stars). The brittle-stars, or serpent-stars as they are frequently called, are much like the true starfishes, the chief distinc- tions being that in the brittle-stars the arms and the disc are sharply distinct from each other, and that the extremely mobile arms are long, slender, and somewhat snake-like. A little closer examination shows that the ambulacral groove has been carried into the interior of the arms, and that here one must search for the ambulacral plates (fig. 93). There is no vent, and the madreporite occurs on. 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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