LIMPET (probably from AS. lempedu. variant of lanlnrcde, lamprey, from \l L. lumpredu, lam prey, from Lat. lombere, to lick + pout. rock; hardly connected with Lat. lepas, Gk. Xercis, limpet, from Neras.
bare rock. from Xereiv, le prin, to strip, to peel). A gastropod mollusk of the prosobranehiate Patclli( I a% in which the shell is nearly conical, not spiral, and with a wide mouth and the apex turned forward. The animal has a large round or oval muscular foot by which it adheres to rocks, the power of creating,' a vacuum being aided by a secretion. Limpets live on rocky coasts, between tidemarks, and re main fixed when the tide is out, as their fringed gills cannot bear exposure to the air, hut move about when the water covers them ; many of them, however, it would seem, remain long on the same spot, which in soft cal careous rooks is found hol lowed to their exact form. The power of adherence is very great, so that. unless surprised by sudden seizure. they are not easily removed without violence sufficient to break the shell. Curious eases of the 'homing instinct' of lim pets are reported by Morgan. If removed from theiL station or 'home' on a rock they will find their way back. even if carried away as far as three feet. They feed on alg.r. The sexes are distinct. The species are numerous and exhibit many varieties of form and color.
The American species is Acma-a testudinalis, and is common along the New England coast. Some of the limpets of warmer climates have very beautiful shells. A species found on the western coast of South America has a shell a foot wide which is often used as a basin. The name is often extended to other shells, especially of the related families Acinwida2 and Fissurelliffic (key hole limpets) and the genus Crepidula (slipper limpets). The fresh-water snails of the genus Aneyelus are called 'fresh-water limpets,' from the• shape of the shell. Limpet-like shells are found fossil in rocks of all ages from the Cam brian upward. and many of the early forms cannot readily be distinguished from modern genera. The oldest is Scenella, a low come shell with reticulate surface, found in the Cambrian. Paheacmata, with a smooth low colic shell, is from the Upper Cambrian. The genera Patella and Am:ea occur from the Silurian upward; Metoptoma, with a straighth anterior margin, is a common Silurian to Carboniferous fossil, and Tryblidium, with a thick oval flattened shell marked by strong imbricating plates, is a curious Silurian form evidently evolved from some early limpet.