The Echinoid Directory

• Test incomplete but apparently ovate with a very weak frontal sulcus at ambitus.
• Apical disc disjunct; genital plate 2 separating ocular plates II and IV. Genital plates 1 and 4 elongate and narrowly separated from posterior oculars. Posterior oculars linearly arranged rather than opposite.
• Ambulacra flush; all five ambulacra petaloid aborally, the two pores being elongate; anterior petal slightly less developed than the rest.
• Oral and posterior surfaces not preserved.
• Aboral tuberculation of scattered primary tubercles set in a groundmass of fine granules. No fascioles.

Lower Cretaceous (Neocomian), Algeria.

Acrolusia gauthieri Lambert, 1920, p. 158. Holotype: Museum National d'Histoire Naturelle, Paris J01258.

• Only the type species.

Irregularia, stem group Atelostomata.

Monotypic.

The distinctive apical disc in this taxon resembles that of the spatangoid Toxaster africanus except that the posterior ocular plates are slightly removed from the rest of the apical disc. Like that taxon also, the anterior ambulacrum is petaloid. Acrolusia is therefore the most derived of the atelostomates with a split disc. It differs from Proholaster in having genital plate 2 extending between ocular plates II and IV and in having all five ambulacra petaloid.

Lambert, J. 1920. Sur quelques genres nouveaux d'echinides. Memoires de la Societe academique de l'Aube 84, p. 145-174, pl. 1.

Mintz, L. W. 1968. Echinoids of the Mesozoic families Collyritidae d'Orbigny, 1853 and Disasteridae Gras, 1848. Journal of Paleontology 42, 1272-1288.