The Echinoid Directory

• Test circular and depressed.
• Periproct trigonal and weakly to strongly oblique; supramarginal in position; widely separated from the apical disc.
• Apical disc with four genital plates, genital plate 2 elongate and extending to the posterior separating the posterior genital and ocular plates.
• Ambulacra with trigeminate plate compounding on the oral surface and simple plating aborally; pore-pairs uniserially arranged.
• Peristome relatively small and sunken; buccal notches feeble or absent.

Cretaceous (Albian to Maastrichtian) of Europe, the Middle East and Cuba.

Nucleolites orbicularis Grateloup, 1836, by original designation.

• A. orbicularis (Grateloup, 1836); Albian - Cenomanian of Europe, North Africa and the Middle East (Arabian Peninsula and Iran) [includes A. atavus Fourtau, 1921, A. paradoxus Hawkins, 1935], and Pygaster costellatus Desor, 1842].
• A. atavus Fourtau, 1921; U. Albian, Egypt.
• A. paradoxus Hawkins, 1835; Campanian-Maastrichtian, Somalia.
• A. riveroi Sanchez Roig, 1949; Maastrichtian, Cuba.
• A. michelini Cotteau, 1860; Cenomanian-Turonian, France and England.

Holectypoida, Pygasterina, Anorthopygidae.

Monophyletic.

Restricted to shallow water facies. Distinguished from Pygaster in having the periproct oblique and far removed from the apical disc. Pileus is very similar, differing only in having pore-pairs offset aborally, so as to form a rather broad band.

A. excisus Lambert 1919 is a Coenholectypus.

Smith, A. B. & Wright, C. W. 1999. British Cretaceous Echinoids. Part 5, Holectypoida, Echinoneoida. Palaeontographical Society Monographs, 343-390, pls 115-129.

Smith, A. B. & Jeffery, C. H. 2000. Maastrichtian and Palaeocene echinoids: a key to world faunas. Special Papers in Palaeontology 63, 1-404.