The Collaborative International Dictionary of English v.0.48:

Paleechinoidea \Pa`le*["e]ch`i*noi"de*a\, n. pl. [NL. See
   Paleo-, and Echinoidea.] (Zool.)
   An extinct order of sea urchins found in the Paleozoic rocks.
   They had more than twenty vertical rows of plates. Called
   also Palaeechini. [Written also Palaeechinoidea.]
   [1913 Webster]