The Echinoid Directory

 Scutellidea with:

• internal buttressing in the form of stellate clusters with well-defined adradial bars and V-shaped interradial channels;
• four gonopores;
• interambulacral zones not greatly narrower than ambulacral zones at ambitus; pores and tube-feet extending onto interambulacral zones on oral surface;
• petals well-developed, with accessory pores in perradial zone;
• basicoronal circlet small, interambulacral elements pointed but not strongly projecting;
• no notches or lunules.

Late Eocene to Recent; Europe, North and Central America, North Pacific (Japan, Kamchatka, Alaska, west coast USA)

(Probably includes stem group members of the Scutellidea)