The Echinoid Directory

• Test small with rounded margin; circular in outline.
• 4 gonopores.
• 10 thick internal radial partitions.
• Petals moderately well developed; open distally.
• Ambulacral pores forming narrow lines that follow plate sutures.
• Interambulacral zones much narrower than ambulacra at ambitus.
• Basicoronal circlet pentagonal without projecting interambulacral plates.
• All interambulacral zones continuous on oral surface.
• Periproct marginal or just inframarginal; opening bounded by third and fourth pair of post-basicoronal interambulacral plates.
• Food grooves forming simple shallow furrows and extending to margin.

Middle to Late Eocene of southern Europe and North Africa.

Scutellina nummularia Agassiz (=S. lenticularis Lamarck, 1816, p. 10) by original designation.

• P. lenticularis (Lamarck, 1816).

Clypeasteroida; Scutellina, stem group scutelliform or laganiform

 

Mooi (1989) reports that adapical interambulacral plating is biserial and provides several figures, including a radiograph of the internal structures. Scutellina is distinguished from Eoscutum by its marginal rather than supramarginal periproct and by its thick, rounded margin. In superficial characters Scutellina resembles Marginoproctus Budin, 1980. Both are small, with 10 simple radial bars, a marginal periproct and without food grooves. However, Marginoproctus is likely to represent a neotenous form of advanced scutelliform related to Echinarachnius or Dendraster (see discussion under Marginoproctus.

Agassiz, L. 1841. Monographies d'Echinodermes vivans et fossiles. 2, Des Scutelles, i-iv, 1-151, pls 1-27. Neuchatel

Mooi, R. 1989. Living and fossil genera of the Clypeasteroida (Echinoidea: Echinodermata): an illustrated key and annotated checklist. Smithsonian Contributions to Zoology 488, 1-51.