The Echinoid Directory

Contributed by Andrew Smith, July 2008

Phymotaxis sp.

Diagnostic Features	Large, hemispherical and relatively thick-shelled. Apical disc small, plating lost - presumed hemicyclic or dicyclic. Ambulacra sinuous above the ambitus; plating polygeminate with 7-8 elements to a compound plate at the ambitus. Plate compounding stomopneustid, with largest element medial and upper and lower elements reaching the perradius. Plating becomes simple adapically. Well developed phyllodes on oral surface. Primary tubercle on each compound ambulacral plate; large and dominating the plate at the ambitus and adorally but confined to just two or three elements towards the apex and becoming small. Interambulacral plates with a primary tubercle and smaller adradial flanking tubercle on adambital plates; adapical and adoral plates dominated by a single primary tubercle. All tubercles imperforate and non-crenulare without surrounding platform to mamelon. Peristome with small, feeble buccal notches. Spines and lantern unknown.
Distribution	Upper Cretaceous (Campanian [=Dordonien inferieur]), Algeria.
Type	Peron Collection?
Classification and/or Status	A species of Phymotaxis