The Echinoid Directory

• Test moderately thick.
• Apical disc usually monocyclic but occasionally with one or more oculars exsert. Generally slightly smaller than peristome. Genital plate 2 significantly larger than other genital plates.
• Tubercles perforate and non-crenulate; areoles hardly incised. Scrobicular tubercles differentiated; not contiguous. Extrascrobicular tuberculation rather heterogeneous. Adoral areoles confluent.
• Ambulacra almost straight with pore-pairs horizontal and separated by raised interporal partition that is as wide as an individual pore. Perradial tuberculation comprises a marginal primary tubercle and an inner secondary tubercle.
• Peristome with ambulacral plates becoming biserially arranged in each column in outer part (not in all species).
• Primary spines short, stout cylinders with blunt termination with a central button. Neck and collar short; the shaft ornamented by dense beaded ribs. Cortical hairs well developed.
• Secondary spines short and apressed.

?Oligocene, Miocene to Recent; Indo-Pacific, central Atlantic and Caribbean.

Cidaris metularia Lamarck, 1816, p. 56, by subsequent designation of Clark & Bather, 1909, p. 88.

• E. metularia (Lamarck, 1816); Pliocene to Recent, Indo-Pacific.
• E. thouarsii (Agassiz & Desor, 1847); Recent, East Pacific.
• E. tribuloides Desmoulins, 1835; Miocene-Recent; Atlantic and Caribbean.
• E. clavata Mortensen, 1928; Recent, Central Atlantic.
• ?E. strombilata Fell, 1954; Oligocene; Australia and New Zealand.

Cidaroida, Cidaridae, Cidarinae.

Presumed monophyletic.

This taxon is characterised by its short stout spines with their beaded ornamentation and blunt crown.

Mortensen, T. 1928. A monograph of the Echinoidea. 1, Cidaroidea. C. A. Reitzel, Copenhagen.

Pomel, A. 1883. Classification méthodique et Genera des Échinides vivante et fossiles. Thèses présentées a la Faculté des Sciences de Paris 503, A. Jourdan, Alger. 131 pp.