Falcated, bent or hooked like a scythe.
Fasciated, filleted, or covered with bands.
Fascicled, clustered together as in a bundle.
Fasciculated, consisting of little bundles.
Fastigate, flat and even at top.
Faux, what can be seen of the cavity of the first chamber of the
shell, by looking in at the aperture.
Ferruginous, of an iron colour, or rust coloured.
Filament, a slender threadlike process.
Filiform, thread-shaped, slender, and of equal thickness.
Fimbriated, fringed.
Fissure, a cleft, a little slit, or narrow chasm.
Flexuous, zigzag, with angles gently winding.
Flexure, a bending.
Fluviatic, of or belonging to a river.
Fluviatile, belonging to fresh water.
Foliaceous, consisting of laminæ or leaves.
Foliated, bent into laminæ or leaves.
Fornix, the excavated part under the _umbo_. It likewise signifies the
upper, or convex shell in the _Ostrea_.
Fragile, brittle, easily broken.
Front, in univalves, when the aperture is turned towards the observer.
Furcated, forked.
Furrow, a small trench or hollow.
Fuscated, darkened, obscured.
Fusiform, spindle-shaped, intermediate between the conical and oval.