The Echinoid Directory

Family Archiaciidae Cotteau & Triger, 1869, p. 426

[nom. cor. Archiacidees]

Diagnosis	Stem group Neognathostomata with: test elongate, projecting anteriorly apical system tetrabasal, very anterior, with four genital pores petal lacking in ambulacrum III; petals well developed in other four ambulacra all ambulacral plates beneath petals with pore-pairs peristome eccentric anteriorly; not invaginated periproct infamarginal, longitudinally ovate phyllodes short and slightly widened basicoronal plate short and wide, not projecting; only a narrow ring of specialized spines and tubercles bordering the opening narrow naked granular zone in interambulacrum 5 orally.
Range	Cretaceous (Aptian-Turonian), North Africa and Europe.
Type	Archiacia L. Agassiz, in Agassiz & Desor, 1847, p. 159.
Remarks	Easily separated from other neognathostomates with double pored ambulacral plates by its shorter or apetaloid frontal ambulacrum and by its apical prolongation. Cotteau, G. H. & Triger, J. 1857-1869. Echinides du Departement de la Sarthe, consideres au point de vue zoologique et stratigraphique. J.-B. Bailliere et Fils, Paris, xv+455 pp.