operculum

• As the wings rose, the feathery operculum-like flaps which protected them were drawn back. —  "You can't leave now," Daniel Holm told his son
• Brain activations reflected differences in observed facial expressions, with emotional expressions activating relatively more the insula / frontal operculum, and neutral ones (blowing up the cheeks) the somatosensory cortices —  CiteULike: Everyone's library
• As this species has a thick calcareous operculum, I removed it, and when it had formed a new membranous one, I immersed it for fourteen days in sea-water, and it recovered and crawled away: but more experiments are wanted on this head. —  On the Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life. (2nd edition)
• But a close examination shows us that this operculum is really composed of two halves, on two separate segments of the body, the segment at the extremity only being the true head, armed with its powerful, sharp, curved jaws. —  My Studio Neighbors
• Then a flap of skin outside the hyoid arch grows back to cover over the gills; this is the operculum (op. in Figures 11 and 12, Sheet 22), and it finally encloses them in a gill chamber, open only by a pore on the left, which resembles in structure and physiological meaning, but differs evidently very widely in development, from the amphioxus atrium. —  Text Book of Biology, Part 1: Vertebrata

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