The Echinoid Directory

• Test small, elongate, smoothly rounded anterior margin, pointed posterior margin, flattened oral surface, greatest width posterior to centre, greatest height at centre, oblique posterior face.
• Apical system tetrabasal, anterior, madreporite extending to posterior separating genital and ocular plates.
• Petals of unequal length, anterior the longest and paired posterior petals the shortest. Interporiferous zones twice width of poriferous zones at greatest width; petals closing distally.
• Periproct supramarginal, midway between apical system and posterior margin, oval, slightly elongated longitudinally, invaginated, slight groove extending posteriorly.
• Peristome anterior, pentagonal, slightly higher than wide; with vertical-walled entrance.
• Bourrelets developed as small rounded points; basicoronal plates longer than wide.
• Phyllodes single pored, broad, with five to seven pores in each outer series and one to three in each inner series.
• Buccal pores present, small.
• Tubercles much larger adorally and distinctly sunken.
• Naked and pitted medial area in interambulacrum 5, and, to a lesser extent, in ambulacrum III.

Upper Cretaceous (Maastrichtian) to Palaeocene of Europe, ?Kazakhstan. Possibly more widely distributed.

Echinites lapis cancri Leske, 1778, p. 256, by original designation.

• P. lapiscancri (Leske, 1778); Maastrichtian of France, Belgium, Netherlands.
• P. elongatui> d'Orbigny, 1856); Early Danian of Belgium.

   

  Lambert & Thiery (1911) list the following species, none of which have been checked: P. neltneri Lambert, 1931 [Cenomanian of N. Africa]; P. lambayensis Lambert, 1936 [Eocene of Senegal]; P. bassea Lambert, 1936 [Campanian of Madagascar]; P. apianus Besairie & Lambert, 1930 [Maastrichtian, Madagascar].

Irregularia; Cassiduloida; Faujasiidae; Stigmatopyginae.

Procassidulus is very similar to Rhynchopygus in petal form, phyllode structure and in having an invaginated periproct. It differs in lacking the strongly pronounced tongue-like projection above the periproctal opening. Procassidulus is also very similar to Gongrochanus, but is easily differentiated as Gongrochanus only has three gonopores, typically has broader arc-like phyllodes, with stronger developed bourrelets, with a median ridge present in the middle of the phyllodes between bourrelets and a cleft-like longitudinal periproct.

Lambert, J. 1918. Considerations sur la classification des echinides atelostomes. 1, Brachygnata et Procassiduloida. Memoires de la Societe academique de l'Aube 82, p. 10-54.

Lambert & Thiery (1909-1925) consider Hardouinia to be a subgenus of Procassidulus. These genera are very similar, and only differ in that Hardouinia typically has broader, more equal petals, with stronger developed phyllodes and more tooth-like bourrelets.

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

J. Lambert & P. Thiery. 1909-1925. Essai de nomenclature raisonnee des echinides. Libraire Septime Ferriere, Chaumont, 607 pp., 15 pls.

A. B. Smith & C. H. Jeffery. 2000. Maastrichtian and Paleocene echinoids: a key to world faunas. Special Papers in Palaeontology 63, 406 pp.

J. W. M. Jagt. 2000. Late Cretaceous-Early Palaeogene echinoderms and the K/T boundary in the southeast Netherlands and northeast Belgium - Part 4: Echinoids. Scripta Geologica 121, 181-375.