The Echinoid Directory

• Test subglobular, flattened below, gently domed above.
• Apical disc small; dicyclic; plates firmly bound to corona. Genital plates wider than tall, with gonopore towards outer point; ocular plates small and pentagonal. A ring of tubercles developed around the inner edge of genital plates encircling the periproct. Periproct relatively large, subcircular.
• Ambulacra straight; pore-pairs small, uniserial; no oral apical differentiation of pore-pairs, but short phyllodes developed adorally.
• Ambulacral plating apparently simple, from ambitus adapically, with all elements reaching the perradius; a single series of small tubercles in each half ambulacrum only, with no perradial space.
• Interambulacral plates wider than tall; with only one or two rows of up to 8 equal-sized tubercles on each. Narrow interradial channel on aboral surface. T-shaped basicoronal plate present with primary tubercle and projecting interradially.
• Tubercles imperforate and non-crenulate, without a platform. Tubercles on oral surface a little larger, with relatively large mamelon.
• Peristome very large (more than half test diameter), subpentagonal with well defined, rimmed buccal notches; no tags.
• No sphaeridial pits.
• Spines and lantern unknown.

Lower Cretaceous (Valanginian), Czech Republic

Magnosiopsis suessi de Loriol, 1901, p. 15, by original designation

• M. suessi de Loriol, 1901; Valanginian, Czech Republic.
• M. ornata Zitt, 1986; Valanginian, Czech Republic.

Euechinoidea,  Echinacea, Arbacioida

Subjective junior synonym of Eucosmus Lambert & Thiery,1914

Distinguished from the very similar Magnosia by having only a double column of tubercles in each ambulacral zone rather than four or more. In E. meslei the ambulacra are so narrow that there are only two columns of ambulacral tubercles which dominate the interporal zone, often alternating. The upper interambulacral plates are tall and wide and the entire aboral surface is made of a single plate in each column.

Zitt, J. 1986. Magnosia Michelin and Magnosiopsis gen. n. (Echinoidea) from the Lower Cretaceous of Stramberk (Czechoslovakia). Casopis pro mineralogii a geologii 31, 371-386, pl. 1.