The Echinoid Directory

• Test small, elongate, highly inflated, flattened oral surface, with greatest width and height posterior to centre, steep sides, adoral surface flattened.
• Apical system anterior, tetrabasal, three genital pores, no pore in genital plate 2, posterior genital plates in contact with each other. Distinct sexual dimorphism in the size of the gonopores, the female\'s being larger.
• Petals narrow, diffuse, pores in petals small, only slightly larger than pores in plates beyond petals, slightly elongated transversely.
• Periproct marginal, longitudinal, with slight groove beneath periproct.
• Peristome anterior, higher than wide, pentagonal.
• Bourrelets weakly developed, forming slight mounds adjacent to peristome.
• Phyllodes broad, double pored, two series of pore-pairs in each half-ambulacrum , 9 or 10 in each outer series, 4 or 5 in each inner series; inner pore of each pair greatly reduced in size.
• No buccal pores.

Late Cretaceous (Cenomanian) of western Europe.

Oolopygus bargesii d\'Orbigny, 1860, p. 456; by monotypy.

• Only the type species.

Irregularia; Neognathostomata; \'catopygids\'.

Mortensen (1948, p. 160) and Lambert & Thiery (1921, p. 354) considered Penestica to be a synonym of Oolopygus. Kier (1962, p. 75) points out that these authors must have been unaware that C. bargesii has double pored phyllodes, as the type species of Oolopygus, O. gracilis, has only single pored phyllodes. Furthermore, although both have three gonopores, in Penesticta it is G2 that lacks a gonopore, whereas in Oolopygus it is G3.

Smith & Wright (2000, p. 419) state that although Kier described the petals of P. bargesii as being only slightly developed, he did not draw attention to the extraordinary narrowness and diffuseness of the petals, in which successive pore-pairs are far more distant from each other than in any Catopygus. Maczynska (1972) concluded that P. bargesii fitted into neither Oolopygus nor Catopygus and favoured resurrecting Pomel\'s genus Penesticta for bargesii, a view held by Smith & Wright (2000).

Penesticta is distinct from the type species of Oolopygus in having all double pores below the petals. Smith & Wright (2000, p. 419) state that this feature is plesiomorphic, and shared primitively with Catopygus. "Penesticta is best interpreted as a sister group to the post Cenomanian clade formed by Oolopygus and Studeria, with Penesticta, Oolopygus and Studeria together forming a clade characterized by their apical disc and petal structure, whose immediate sister group is Catopygus" (Smith & Wright, 2000).

Pomel, A. 1883. Classification méthodique et genera des Échinides vivante et fossiles. Thèses présentées a la Faculté des Sciences de Paris pour obtenir le Grade de Docteur ès Sciences Naturelles, 503, 131 pp. Aldolphe Jourdan, Alger.

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.

S. Maczynska. 1972. On some representatives of the genus Catopygus L. Agassiz (Echinoidea) from the Upper Cretaceous. Prace Paleozoologiczne, Prace Muzeum Ziemi, Waszawa, Poland, 20; pp. 173-185, 4 pls.

T. Mortensen. 1948. A monograph of the Echinoidea: 4 (1): Holectypoida, Cassiduloida. Reitzel, Copenhagen, 363 pp., 14 pls.

A. B. Smith & C. W. Wright. 2000. British Cretaceous echinoids. Monograph of the Palaeontographical Society, pp. 391-439, pls 130-138.