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.