| The chimaeran hyoid is, it turns out, quite happy supporting the operculum and has no interest in the palatoquadrate. |
| The halecostomes, of which Amia is an example, have an opercular dilator muscle originating on the mandible which opens the operculum. |
| The operculum illustrated by Reed does not match in outline the conch, and is here considered to be a different taxon. |
| Avicularia are small heterozooids in which the zooecium and operculum form a beak-like, snapping structure that deters small predators. |
| Whenever muscular control of the operculum was established, it was probably based on the cleithrum. |
| So the spiral of the operculum of a dextral snail is invariably counterclockwise, while that of a sinistral shell is the opposite. |
