The Echinoid Directory

Plagiopygus Lambert, 1898, p. 162

[=Pleuropygus Lambert & Thiery in Lambert, 1913, p. 127 (objective) ]

Diagnostic Features	Test of medium size, oval inflated, greatest width posterior to centre; margin gently rounded except for slight posterior truncation, oral surface slightly depreesed towards peristome. Apical system anterior, monobasal, madreporite a little inflated. Petals long and well developed, interporiferous zones over twice width of poriferous zone; slightly bowed closing distally; the two poriferous zones in each petal of unequal length, depressed. Periproct marginal to slightly supramarginal; transverse with slight groove beneath opening. Peristome anterior, depressed, pentagonal. Bourrelets confined to vertical walls of peristome, slightly convex. Phyllodes widened, single pored, with two series in each half ambulacrum. Buccal pores and sphaeridial pits present. Tubercles larger adorally. Naked median band, granular and without pits, in interambulacrum 5.
Distribution	Middle Eocene of France.
Name gender	masculine
Type	Nucleolites grignonensis Defrance, 1825, p. 214, by original designation.
Species Included	P. grigonensis Defrance, 1825, Middle Eocene of France Lambert included at least two other species in this genus that have not been examined.
Classification and/or Status	Irregularia; Cassiduloida; Cassidulidae. Subjective junior synonym of Rhyncholampas A. Agassiz, 1869.
Remarks	Kier (1962) considered Plagiopygus a subjective junior synonym of Rhycholampas. P. M. Kier.1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections 144 (3) 262 pp. Lambert, J. 1898. Note sue les échinides de la Craie de Ciply. Bulletin de la Société belge de Géologie, de Paléontologie et d'Hydrologie, 11, 141-190, pls 2-5.