\Pa`le*["e]ch`i*noi"de*a\, n. pl. [NL. See
{Paleo-}, and {Echinoidea}.] (Zo["o]l.)
An extinct order of sea urchins found in the Paleozoic rocks.
They had more than twenty vertical rows of plates. Called
also {Pal[ae]echini}. [Written also {Pal[ae]echinoidea}.]