The Echinoid Directory

• Test flattened above and below; ambitus rounded.
• Apical disc relatively small; thick, forming raised platform; dicyclic; plates firmly bound to corona. Genital plates pentagonal, projecting interradially; gonopores marginal; rising towards periproct, where there is ring of perianal tubercles. Ocular plates smaller and projecting. Ring of tubercles surround the periproctal opening. Small sutural pits developed. Periproct circular.
• Ambulacra straight and rather broad; pore-pairs small, uniserial, the two pores separated by a raised interporal knob; aboral pore-pairs slightly larger than oral pore-pairs; ambulacra remain uniserial more or less to peristome.
• Ambulacral plating in triads, with compounding in goniopygid style; two larger elements extending to the perradial suture, the upper being smaller, alternating with a small demiplate. Primary tubercle on each plate with small perradial zone of granules adapically. Ambulacral tubercles much smaller than interambulacral tubercles.
• Interambulacral plates a little wider than tall; with a large primary tubercle on each; secondary tubercles and miliary granulation present interradially and adradially; areoles confluent in vertical series. Primary tubercles imperforate and non-crenulate, with small mamelon surrounded by a distinct platform.
• Basicoronal interambulacral plate absent.
• Peristome subcircular, buccal notches sharp with rim.
• Shallow sphaeridial pits present adradially beneath primary tubercles on adoral compound plates.
• Spines and lantern unknown.

Cretaceous (Cenomanian - Maastrichtian), North Africa and the Arabian Peninsula.

Goniophorus problematicus Cotteau, 1880, p. 121, by monotypy.

• G. problematicus Cotteau, 1880; Cenomanian, Algeria.
• G. hattaensis Ali, 1992; Maastrichtian, Arabian Peninsula.

Echinacea, Arbacioida, Glyphopneustidae.

Somewhat like Arbia, but distinguished from that genus by having only a single primary tubercle to its interambulacral plates in contrast to Arbia which has two subequal tubercles on subambital plates and a broad naked interradial band adapically. The Maastrichtian representative of this genus was described in detail by Smith (1995).

Pomel, A. 1869. Revue des échinoderms et de leur classification pour servir d’introduction à l’étude des fossiles, 67 pp. Deyrolle, Paris. [not seen]

Smith, A. B. 1995. Late Campanian- Maastrichtian echinoids from the United Arab Emirates - Oman Borders Region. Bulletin of the Natural History Museum, London (Geology Series) 51(2), 121-240.