''Eucidaris'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of cidaroid sea urchins known as slate pencil urchins. They are characterised by a moderately thick

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...

, a usually monocyclic apical disc, perforate and non-crenulate tubercles and nearly straight

ambulacra Ambulacrum is an architectural word that denotes an atrium, courtyard, or parvise in front of a basilica or church that is surrounded by arcades or colonnades, or trees, and which often contains a fountain A fountain, from the Latin "f ...

with horizontal pore pairs. The primary spines are few and widely spaced, stout with blunt flat tips and beaded ornamentation and the secondary spines are short and apressed. They originated in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

and extant members of the genus are found in the tropical Indo-Pacific Ocean, East Pacific, Atlantic Ocean and

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

Species

The World Register of Marine Species lists the following species: * '' Eucidaris australiae'' Mortensen, 1950 * † '' Eucidaris coralloides'' Fell, 1954 * '' Eucidaris galapagensis'' Döderlein, 1887 * ''

Eucidaris metularia ''Eucidaris metularia'', the ten-lined urchin, is a species of sea urchins in the family Cidaridae. It is found in shallow parts of the Indo-Pacific Ocean and is characterised by its sparse covering of banded, flat-tipped spines. Description ...

'' (

Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolo ...

, 1816) * † '' Eucidaris strobilata'' Fell, 1954 * '' Eucidaris thouarsii'' ( Agassiz & Desor, 1846) * '' Eucidaris tribuloides'' (

, 1816) ;Species brought into synonymy: * ''Eucidaris clavata'' Mortensen, 1928: synonym of ''Eucidaris tribuloides'' (Lamarck, 1816) Eucidaris metularia.jpg, ''

'' Eucidaris Baltimore Aquarium.jpg, '' Eucidaris tribuloides'' Cidaroid urchin in Galapagos.jpg, '' Eucidaris galapagensis''

References

Pomel, A. 1883. Classification méthodique et Genera des Échinides vivantes et fossiles. Thèses présentées à la Faculté des Sciences de Paris pour obtenir le Grade de Docteur ès Sciences Naturelles 503, Adolphe Jourdan, Alger, 131 pp
{{Taxonbar, from=Q3458737 Cidaridae Cidaroida genera