The Echinoid Directory

Cyathocidaris Lambert, 1910, p. 12

Diagnostic Features
  • Test large, subspherical; thick.
  • Apical disc not seen.
  • Interambulacra with 8-9 plates in a series. Primary tubercles perforate and non-crenulate; mamelons increase in size adapically; areoles circular and incised; separated (scrobicular circles confluent adorally). Plates wider than tall.
  • Scrobicular circles differentiated from extrascrobicular tubercles. Extrascrobicular zones only developed interradially where there are small uniform granules more or less aligned into horizontal rows with neural grooves between every two.
  • Interradial zone depressed but no clear sutural pits (preservation, however, is not good enough to say if they are definitely absent).
  • Ambulacra sinuate; pore-pairs subconjugate with the two pores separated by an interporal zone slightly wider than a pore. Pore-zone hardly sunken. Perradial zone similar in width to pore zone; with two subequal tubercles to each plate.
  • Primary spines variable; rather fat and fusiform with the shaft covered in semi- to well-aligned thorns. Distally expanded into a cup-shaped crown which may be very expansive.
  • Lantern and girdle unknown.
Distribution
Upper Cretaceous - Palaeocene, Europe, Antarctic.  Possibly younger.
Name gender feminine
Type
Cidaris cyathifera Agassiz, in Agassiz & Desor, 1847, p. 329, by original designation [species originally based on spines, but Lambert (1911) figured a test with associated spines].
Species Included
  • C. cyathifera (Agassiz, 1840); Santonian, France.
  • C. erebus Lambert, 1910; Maastrichtian-Palaeocene, Seymour Island, Antarctica.
  • C. nordenskioldi Lambert 1910; Maastrichtian-Palaeocene, Seymour Island, Antarctica.
Classification and/or Status

Cidaroida, Cidaridae, Cidarinae.

?monophyletic

Remarks

Distinguished from Stereocidaris by its more pronounced distal cup to primary spines and absence of fully formed adapical plate lacking a primary tubercle.

Lambert, J. 1910. Description des échinides des terrains néogène du Basin du Rhône. Mémoires de la Société paléontologique Suisse, 37, 1-48, pls 1-3.

Lambert, J. 1910. Les echinides des Iles Snow-Hill et Seymour. Wisssenschaftliche Ergebnisse der Schwedische Sudpolar Expedition 1901-1903 3 (11), 15 pp, 1 pl.

Lambert, J. 1911. Etudes sur les echinides Cretaces de Rennes-les-Bains et des Corbieres. Bulletin de la Societe d\'Etudes scientifiques de l\'Aude 22, p. 108.

Mortensen, T. 1928. A monograph of the Echinoidea. 1, Cidaroidea. C. A. Reitzel, Copenhagen.