It has a bar behind the operculum on its shoulder.

A large black spot approximately the same size as the eye is present on the operculum.

The operculum lies on the top rear part of the foot.

The dark edge of the operculum also fades with age.

The operculum is not observed, the specimens now described being dead.

The operculum has a small black spot on its upper margin.

The operculum of the case is covered with small pebbles.

The head end of the larval case is closed by a operculum.

The dark red operculum is granulated on its inner side.

Without an operculum, other methods, such as ventilation, are required.

A prominent spot of crimson red is seen on the operculum.

They also have an operculum, which helps them breathe without having to swim.

The operculum may provide some protection against smaller predatory species.

The operculum is nearly twice as wide as the eye.

The operculum is either red or has two red rings.

It was not possible for the air to escape because of the valve or operculum mentioned.

Th operculum is almost clear, with the inner dark brown surface showing through.

At the other end the tube is sealed by a circular operculum.

The operculum has two spines which may be concealed by skin.

The operculum is white, inside stained with blue above.

At the large end, the operculum is clearly visible.

There are no scales on the snout, head or operculum.

The skull proper was joined by the bones of the operculum.

It is named for the large, orange-red spot found on each operculum.

He pushed the second operculum away and entered the worldship wall.