The Echinoid Directory

Discoides Parkinson, 1811, p. 20

[=Discoidea Agassiz, 1835, p. 137 (objective); =Protocyamus Gregory, in Lankester, 1900, p. 316 (objective) ]

Diagnostic Features
  • Periproct oval, on oral surface; separated from the peristome by two interambulacral plates and extending almost to the ambitus.
  • Apical disc with five genital plates, the posterior being imperforate and lacking a gonopore; hydropores usually confined to genital plate 2.
  • Ambulacra with trigeminate plate compounding on the oral surface and simple plating aborally; one plate in each triad reduced in size and occluded from the perradial suture.
  • Internal buttressing of thick rounded ridges extending radially away from the perignathic girdle.
Distribution
Early Cretaceous (Aptian) to Late Cretaceous of Europe and the Caribbean.
Name gender masculine
Type
Echinites subuculus Leske, 1778, by monotypy.
Species Included
  • D. decorata (Desor, 1842); Aptian - Albian France and England.
  • D. subuculus (Leske, 1778); Late Albian - Cenomanian, Europe.
  • D. cubae (Hawkins, 1913); Upper Cretaceous (Campanian-Maastrichtian), Cuba
Classification and/or Status

Holectypoida, Holectypidae, Discoidinae.

Paraphyletic, by exclusion of Camerogalerus.

Remarks

A common fossil in sandy facies of Cenomanian age across north western Europe. Camerogalerus differs in having hydropores over all five genital plates, in having sharp, rather than rounded, internal butresses and in having two of the three ambulacral elements as demiplates separated from the perradial suture. Species of Discoides are distinguished on details of the apical disc plating and strength of internal butressing.

Parkinson, J. 1811. Organic remains of a former world, 3, xv + 479 pp., 22 pls. Sherwood, Neely and Jones, London.

Smith, A. B. & Wright, C. W. 1999. British Cretaceous Echinoids. Part 5, Holectypoida, Echinoneoida. Palaeontographical Society Monographs, pp. 343-390, pls 115-129.