The Echinoid Directory

Plesiocorys Pomel, 1883, p. 45

Diagnostic Features	Test ovate with flat base, domal upper surface and weak anterior sulcus. Apical disc subcentral with four gonopores. All ambulacra with simple, rounded pore-pairs adapically. Plastron plating uniserial with 2 to 4 post labral plates arranged uniserially. Peristome small and ovate; facing downwards. Periproct on short truncate posterior face. Aboral tuberculation uniform and fine. Marginal fasciole may be present in small individuals of the type species.
Distribution	Upper Cretaceous (Turonian to Santonian).
Name gender	feminine
Type	Holaster placenta Agassiz, in Agassiz & Desor, 1847, p. 27(133), by subsequent designation of Wagner & Durham, 1966, p. U533.
Classification and/or Status	Holasteroida, Cardiasteridae. Monophyletic.
Remarks	Differs from Holaster and Offaster in having plastron plating uniserial over most of the oral surface. The two subgenera are differentiated on whether there is a distinct anterior sulcus (present in P. (Sternotaxis), absent in P. (Plesiocorys)). 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. Smith, A. B. & Wright, C. W. 2003. British Cretaceous echinoids. Part 7, Atelostomata, 1. Holasteroida. Palaeontographical Society Monographs, London. Pp. 440-568, pls 139-182.