Conoclypeidae

Conoclypeidae, an extinct family of irregular Sea-urchins, of much interest, as they are intermediate between the toothed and toothless forms. They are provided with powerful ossicles supporting the teeth, which are, however, diminished in size; these members of this family also possess the star-shaped structure known as the "floscelle," consisting of five ridges and five depressions, all of which radiate from the mouth. This floscelle is the typical character of the toothless order, Cassiduloidea, in which the genus Conoclypeus and its allies were included before the discovery of the teeth. There are no British representatives of the family, which was most abundant in the Eocene period in Central Europe.