Pediform, foot-shaped. Pelagic, belonging to the deep sea. Pellicle, the skin or film. Pellucid, transparent, clear, bright. Pentagonal, having five angles. Perforated, pierced with holes. Pervious, admitting passage. Phosphorescent, emitting light in the dark. Pillar, in univalves is the internal continuation of the columella or inner lips, and extends from the _base_ to the _apex_. Pinnated, winged. Plaited, folded. Plaits, folds. Plicated, folded or plaited, as in the pillar of the volute tribe. Plumose, having a feathery appearance. Polythalmous, divided into several chambers. Porcate, marked with raised longitudinal lines. Porrected, projecting. Prismatic, generally applied to the colours of shells, being like those of the prism; iridescent. Produced, lengthened out. Protrude, to thrust forward. Protuberances, plaits higher or more elevated than the parts adjoining. Punctuated, with small hollows like the punctures of a thimble. Pyriform, pear-shaped. Q. Quadrangular, having four right angles. Quadruplicated, having four plaits. R. Radiated, furnished with rays. Radicated, is when the shell is fixed by the base to another body. Rectangular, having right angles. Recurvated, turned backward. Recurved, bowed back. Reflected, thrown backward, or bent back. Reflex, } the same as _recurvated_. Reflexed, } Refracted, abruptly bent, as if broken. Reniform, kidney-shaped. Repand, with a serpentine margin. Replicated, folded or plaited, so as to form a groove or channel. Reticulated, formed like a piece of network. Retroflected, bent backward. Retrousse, cocked up, turned up. Retroverted, turned back. Retuse, ending in an obtuse sinus. Rotundated, blunted, or turned at the edge. Reversed spire, is when the volutions turn the reverse way of a common corkscrew, or to the sun’s apparent motion. Revolute, rolled backward. Ribbed, having longitudinal or transverse ridges. Ridge, the upper part of a slope. Rima, the interstice between the valves when the hymen is removed. Rostrum, the beak; the extension of the shell, in which the canal is situated. Rotund, round, circular, spherical. Rudimentary, the commencement or first elements of anything; generally applied to the indistinct teeth of shells. Rufous, of a reddish colour. Rugose, rugged, full of wrinkles. S. Sanguinaceous, of a blood colour, or resembling blood. Scabrous, rough, rugged, harsh, or like a file. Scalloped, indented at the edges. Scrobiculate, pitted, having the surface covered with hollows. Scorbiculous, a depression or cavity. Scutellated, } shield-shaped. Scutelliform, } Seam, the line formed by the union of the valves. Semi, is used in composition in the sense of half.