The Echinoid Directory

Baudhuinipygus Vadet, 1997, p. 76

Diagnostic Features
  • Test subovate, of small to medium size, moderately inflated, with slightly truncated posterior margin, greatest width posterior to centre; low domal in profile.
  • Apical system anterior, tetrabasal, with four genital pores, no catenal plates (advanced form).
  • Petals of equal length, slightly bowed, with outer pore-pair more elongate than inner, all ambulacral plates double pored.
  • Periproct supramarginal, visible from above, with groove extending from lower edge of periproct opening to posterior edge of test.
  • Peristome anterior, subpentagonal.
  • Bourrelets absent.
  • Phyllodes slightly broadened, with two series of double pores in each half-ambulacrum.
  • No buccal pores.
Late Jurassic (Tithonian) of England and France.
Name gender masculine
Echinobrissus haimii Wright, 1859, p. 353; by original designation of Vadet, 1997, p. 76.
Species Included
  • Vadet (1997) included two species when erecting this genus,
  • Nucleolites [Baudhuinipygus] brodiei (Wright, 1859); Tithonian, England, France.
  • Nucleolites [Baudhuinipygus] haimei (Wright, 1859); Tithonian, England, France.
Classification and/or Status

Irregularia; Neognathostomata; 'nucleolitid'.

Subjective junior synonym of Nucleolites Lamarck, 1801.


This genus is similar to Nucleolites, having a distinctly supramarginal periproct, with a short, but well defined anal sulcus. Vadet's (1997) assertion that the periproct differentiates this genus is unreliable, as a wide variety of periproctal shapes exist among species of Nucleolites. Such species differ from Phyllobrissus, where the periproct is situated on an almost vertical face, close to the margin, with only a very short groove extending from the periproct.

A. Vadet. 1997. Echinides du Callovien de la Sarthe et de l'Orne. II. A les echinides irregulies: analyse et evolution. Memoires de la Societe Academique du Boulonnais Serie Histoire Naturelle, 18 (2), 73-140.