echinometridæ

from The Century Dictionary.

• A family of regular desmostichous or endocyclical sea-urchins, of the order Endocyclica or Cidaridea, having a long oval shell, imperforate tubercles, oral branchiæ, and ambulacral areas in arcs of more than three pairs of pores. Echinometra and Podophora are the leading genera.