The Echinoid Directory

• Test subglobular, flattened below, gently domed above.
• Apical disc small; dicyclic; plates firmly bound to corona. Genital plates hexagonal, with gonopore towards interradial point; ocular plates small and pentagonal, projecting beyond genitals. All plates covered in fine granules only. Periproct small, subcircular to subpentagonal.
• Ambulacra straight; pore-pairs uniserial except adorally where they expand to form short phyllodes. Aboral pore-pairs a little larger than adoral pore-pairs.
• Ambulacral plating trigeminate throughout; plates composed of a single large element that forms most of area, plus two small demiplates, one above the other below.
• Interambulacral plates wider than tall.
• Tuberculation: aboral surface to ambitus without primary tubercles; plates covered in a fine network of epistroma with scattered small hyaline pustules in both ambulacral and interambulacral zones; these sutured and non-articulating; about 12-15 to an interambulacral plate, not forming rows. Primary tubercles developed only subambitally, a single series only on ambulacral and interambulacral plates. Primary tubercles imperforate and non-crenulate, with relatively large mamelon and poorly defined platform.
• Basicoronal plate probably absent or very small.
• Sphaeridial pit single and perradial.
• Peristome subcircular, with shallow but distinct buccal notches and no tag.
• Spines and lantern unknown.

Cretaceous to Palaeocene, Europe, North Africa, North and South America.

Pomel 1883, p. 82 listed four species under his new genus, Codiopsis lorini, C. meslei, C. nicaisei and C. aissa, all Cretaceous. I here select the first of these, Codiopsis lorini Cotteau, 1851, p. 287, as type species of Hemicodiopsis Pomel, 1883, p. 82.

• C. (H.) alpina Valette, 1906; Aptian, France
• C. (H.) lorini Cotteau, 1851; Neocomian, France.
• C. (H.) jaccardi Cotteau, 1866; Neocomian, France.
• C. (H.) disculus Peron & Gauthier, 1881; Campanian to Danian, Europe and North Africa.
• C. (H.) castroi (Maury, 1930); Campanian-Maastrichtian, Brazil, Cuba.
• C. (H.) pulchella Smith & Rader, 2009; Albian, Texas, USA
• C. (H.) stephensoni Cooke, 1953; Maastrichtian, USA.

Euechinoidea, Echinacea, Arbacioida, Arbaciidae.

Subgenus of Codiopsis.

This genus was distinguished from Codiopsis by Pomel (1883) by having just a single large primary tubercle on adoral interambulacral plates. It is probably worth distinguishing at subgeneric level. Even in very small C. doma there are two primary series of tubercles adorally, so the difference is not size related.

Pomel, A, 1883. Classification methodique et genera des echinides vivants et fossils. Alger, Paris.