The Echinoid Directory

• Test weakly cordiform and subrostrate.
• Apical disc disjunct; anterior portion compact; tetrabasal with ocular plates II and IV pierced by posterior genital pores. Posterior oculars a short distance above periproct and always separated from the periproct opening.
• Paired ambulacra flush, subpetaloid to petaloid with pore-pairs distinctly elongate and circumflexed.
• Pore-pairs in ambulacrum III small and rudimentary.
• Frontal ambulacrum forming a shallow groove that deepens towards ambitus and continues to peristome.
• Phyllodes hardly developed.
• Plastron plating protosternous, with wide labral plate in broad contact with both succeeding plates.
• Peristome ovate and close to anterior border; facing down; with faint sulcus to anterior.
• Periproct towards top of truncate posterior face.

Middle Jurassic (Bathonian) to Upper Jurassic (Oxfordian), ?Lower Cretaceous (Valanginian), Europe, North Africa.

Metaporinus michelini L. Agassiz, 1844, p. 730 by monotypy.

• M. michelini Agassiz, 1844; Oxfordian, France [includes M. censoriensis Cotteau, 1855]
• M. sarthacensis Cotteau, 1875; Callovian, France.
• M. minensis Gauthier, 1890; Oxfordian, Algeria.
• possibly also M. gueymardi Gras, 1848; Valanginian, France [type species of Dialyaster Pomel, 1883].

Irregularia, stem group Atelostomata, Tithoniidae.

Presumed monophyletic.

The type specimen of the type species is an internal siliceous mould from the Corallian of Duyes. The apical disc plating is illustrated as compact, with the oculars exsert in Cotteau's drawing (1867, pl. 2, fig. 4), but it is probably not possible to identify these oculars from an internal mould. Vadet et. al (1998) provide detailed information on M. sarthacensis, which appears to be close to the type species as far as it is possible to tell.

Pomel, 1883, p. 49, distinguished Metaporinus from Tithonia by its petaloid paired ambulacra, but the ambulacra are, at most, subpetaloid in the type species. Tithonia also differs in having its posterior oculars in contact with or very close to the periproct. The subpetaloid to petaloid paired ambulacra and apetaloid anterior ambulacrum which is near vertical and sunken, distinguish this genus from Tetraromania

The attribution of M. gueymardi to this genus is tentative.

Agassiz, L. 1844. Bulletin de la Societe geologique de France (2) 1, p. 730. [a notice in a meeting report, without separate title]

Vadet, A. Nicolleau, P. & Pineau, J. P. 1998. Echinides du Callovien de la Sarthe et de l\'Orne. II-B: Les echinides irreguliers. Memoires de la Societe Academique du Boulonnais Serie Histoire Naturelle 19, 1-128, pls 1-40.