Holasteroida

views updated

Holasteroida (subphylum Echinozoa, class Echinoidea) An order of irregular echinoids in which the apical system is elongated, but not disjunct. In the plastron, the labral plate is followed by a single, large plate, and a varying number of plates in a single column. The Holasteroida first appeared in the Lower Cretaceous.

About this article

Holasteroida

Updated About encyclopedia.com content Print Article Share Article