The Echinoid Directory

Family Holasteridae Zittel, 1879, p. 532

Diagnosis	Basal Meridosternata with: apical disc of standard holasteroid structure, with four gonopores; frontal groove present from ambitus to peristome as shallow furrow; usually also extending adapically; plastron plating meridosternous with sternal plate similar in size to episternal plates and with episternals biserially offset. In some taxa episternals reaching opposite adradial suture making plastron metasternous; pores in anterior ambulacrum small and differentiated from those in the paired ambulacra aborally.
Range	Cretaceous (Hauterivian to Maastrichtian); northern hemisphere.

Diagnosis

apical disc of standard holasteroid structure, with four gonopores;
frontal groove present from ambitus to peristome as shallow furrow; usually also extending adapically;
plastron plating meridosternous with sternal plate similar in size to episternal plates and with episternals biserially offset. In some taxa episternals reaching opposite adradial suture making plastron metasternous;
pores in anterior ambulacrum small and differentiated from those in the paired ambulacra aborally.

Range

Cretaceous (Hauterivian to Maastrichtian); northern hemisphere.