The presence of these opercula in swallows' nests is very curious,[164] and leads one to suppose that they must have been brought there from some distant shore in the swallow's stomach.
I found them to be the hard polished calcareous opercula of some species of Turbo, and although their worn state precludes the idea of identifying the species, yet I am confident that they belong to no European Turbo.
This is the case with shells of the genus Turbo and Phasianella, which are on this account distinguished from those of the genus Trochus; the opercula of the latter being horny or corneus.
The opercula of various shells differ in the first place as to their chemical composition.
The opercula of multivalve shells are composed of two or four pieces, which are called the opercular valves.
D--Ampullae likewise placed in sand which is contained in a box, of which the spouts from the opercula extend crosswise into ampullae placed under them.
C--Ampullae placed in the sand which is contained in a box, the spouts of which reach from the opercula into ampullae placed under them.
Watch the movements of the opercula and mouth, and determine what movements are concerned in breathing and their order.
Any lidlike or operculiform process or part; as, the opercula of a dental follicle.
Defn: Having numerous spiral coils round a center or nucleus; -- said of the opercula of certain shells.
The opercula have been utilized a great deal in the classification of the /Gasteropoda/, and especially in some groups that have become terrestrial in habit.
The opercula vary to a great extent in the different genera; in some cases they are calcareous, in others cartilaginous.
The best way to accomplish this is to pack the dry shells with cotton wool, and then fasten the opercula to the wool by means of a little gum tragacanth or acetic glue.
To the same category belong also the opercula of Fishes, and even their scales.
Their shells are branchialopercula (as in the Fishes).
Proboscis having thick lips, and retractile into a large cephalic cavity; alulæ or halteral opercula arrested--Hypocera to Dolichocera.
Body quite regular with large scales, mouth of moderate size with scythe-shaped teeth, branchial opercula armed.
Tolerably naked or microlepidal, cylindriform or very much compressed, with small head and mouth; the teeth very feeble, only like a brush; the branchial opercula without spines.
The branchiæ with their operculaare similarly formed to the branchial plates and shells of the Bivalve Mollusca.
They are desiccated air-branchiæ, alary opercula or elytra, and consequently indicate that feature of the Insect, which has continued to work its way into the class of Fishes.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "opercula" in a variety of sentences. We hope that you will now be able to make sentences using this word.
