The Echinoid Directory

 Echinothurioids with:

• primary tubercles perforate and non-crenulate without sunken areoles
• ambulacra trigeminate with triads forming multielement compound plates adorally, with adoral tubercles varying in size
• the two small elements as demiplates along adradial margin
• pore-pairs forming a broad adradial band adorally
• peristomial membrane with series of wedge-shaped ambulacral plates
• spines simple with rounded tip.

Middle to Upper Jurassic; Europe.

Distinguished from other echinothurioids by having well developed adoral phyllodes and by the complex ambulacral compounding that develops adorally.

Groom, T. T. 1887. On some new features in Pelanechinus corallinus. Quarterly Journal of the Geological Society of London 43: 703-714.