The Echinoid Directory

• Test thick-shelled, medium sized, subquadrate in outline, somewhat inflated; adoral surface flattened to slightly pulvinate; tumid oral surface, distinctly concave towards the peristome.
• Apical system anterior, tetrabasal with four genital pores.
• Petals broad, equal poriferous zones, bowed and closing distally.
• Periproct supramarginal, longitudinal, with distinct subanal sulcus.
• Peristome anterior, pentagonal, wider than high, surrounded by small rounded bourrelets.
• Bourrelets well developed, inflated, projecting.
• Phyllodes broad, single pored, with two series of pores in each ambulacrum.
• Buccal pores present.
• Distinct granular tubercle-free zone between the peristome and the posterior surface.

Cretaceous (Turonian to Maastrichtian) of North Africa, America and India.

Echinobrisus setifensis Cotteau, 1866, p. 151, by original designation.

• P. ammonis (Fourtau, 1914); Turonian, Egypt.
• P. oldhamianus (Stoliczka, 1873); Ariyaloor Group, southern India.
• P. pyramidalis (Peron & Gauthier, 1881); Maastrichtian, North Africa.
• P. rawdahensis (Smith, 1995); Mid Maastrichtian, United Arab Emirates.
• P. setifensis (Cotteau, 1866); Maastrichtian, North Africa.

Irregularia; Cassiduloida; Faujasiidae; Stigmatopyginae.

Petalobrissus is similar to Australanthus in having a supramarginal periproct in a longitudinal anal sulcus, with bowed petals (slightly more parallel in Australanthus) that taper distally, and where the posterior petals are longer than the lateral petals. Petalobrissus differs from Australanthus in having a tetrabasal apical system (monobasal in Australanthus), less projecting bourrelets and phyllodes that have a more developed inner series of pores.

P. M. Kier. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections, 144 (3) 262 pp.