Watch the movements of the opercula and mouth, and determine what movements are concerned in breathing and their order. [Please select]
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From the remarks on this genus, made at Plate 103, the fact of their opercula being either shelly or horny, is sufficiently established. [Please select]
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This is proved from the fact, that among the Naticæ some have horny, and some shelly, opercula: in Phasianella, this part is, in some species, almost flat, in others remarkably convex; in _Turbo, Lam. [Please select]
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This latter formation is by far the most frequent, and leads to the conclusion that the majority of these shells have their opercula horny. [Please select]
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