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The Echinoid Directory

Contributed by Jenna Sullivan, May 2007

Glyptocidaris? thomsoni d'Archiac and Haime, 1853, p. 207

[=Echinometra thomsoni d'Archiac & Haime, 1853, p. 207]

Diagnostic Features Holotype a very badly weathered individual from which few details can be made out
  • Circular and depressed in profile; ambitus slightly below mid-height.
  • Apical disc small; plating not seen.
  • Ambulacra polygeminate with 6-7 pore-pairs arranged in an arc on ambital and aboral plates.  Plate compounding phymosomatid.  A single large primary tubercle on each plate.
  • Interambulacra wide, with a single large primary tubercle on each ambital and aboral plate; joined by small secondary adradial tubercles beneath the ambitus.
  • Interradial zone somewhat depressed and apprently rather naked adapically.
  • Primary tubercles imperforate and crenulate.
  • Oral surface largely obscured by sediment.
Distribution Eocene, Chaine d'Hala, Sind, Pakistan.
Classification and/or Status Possibly a species of Glyptocidaris, but too poorly preserved.
Remarks

The holotype is a badly worn test of a regular euechinoid.


Archiac, E.J.A.D. de St. S., le Vicompte d' & Haime, J. 1853. Description des animaux fossiles du groupe Nummulitique de l’Inde, 373 pp., 36 pls. Gide and. Baudry, Paris.