Rudistes \Ru*dis"tes\ (r[udd]*d[i^]s"t[=e]z), n. pl. [NL., fr.
L. rudis rough.] (Paleon.)
An extinct order or suborder of bivalve mollusks
characteristic of the Cretaceous period; -- called also
{Rudista}. See Illust. under {Hippurite}.
[1913 Webster]