Amphineura (phylum Mollusca) A class of elongate, bilaterally symmetrical, marine molluscs in which the shell, if present, consists of seven or eight overlapping, calcareous plates on the dorsal surface. The head is poorly differentiated, if at all. Some possess an effective radula. The posterior mantle cavity contains the anus and gills. A broad, flat foot occurs ventrally and is used for creeping. The anatomy is typically molluscan, with a primitive, ganglionic nervous system. All are blind and lack tentacles. Sexes are generally separate. The class first appeared in the Upper Cambrian.

Amphineura (phylum Mollusca) Class of elongate, bilaterally symmetrical, marine molluscs, first appearing in the Upper Cambrian, in which the shell, if present, consists of seven or eight overlapping, calcareous plates on the dorsal surface. The class comprises the Polyplacophora (chitons), and the Aplacophora which have no fossil record.