The Echinoid Directory

Thagastea Pomel, 1888, p. 373

[=Thegaster Duncan, 1889 (nomen null.)]

Diagnostic Features
  • Test small (up to 30 mm) and ovate. inflated and rounded in profile with height about 80% of length.
  • Internal supports absent.
  • Apical disc with four gonopores. About 20 hydropores scattered over anterior part of disc.
  • Petals well developed for size, more or less parallel and open distally.
  • Interambulacral plating continuous and zones only slightly narrower than ambulacral zones at ambitus.
  • Interambulacral basicoronal plates small and undifferentiated.
  • Aborally interambulacral zones forming a single series adapically of 2 successive plates.
  • Periproct opening on aboral surface close to peristome, opening bounded by first and second paired post-basicoronal plates.
  • Sort unbranched food groove in anterior ambulacrum and to a lesser extent in other ambulacra.
  • Peristome central, small, sunken.
  • Ambulacral zones slightly wider than interambulacral zones at ambitus.
Distribution
Eocene, North Africa.
Name gender feminine
Type
Thagastea wetterlei Pomel, 1888, by original designation.
Species Included
  • Several fossil species have been assigned to this genus but need re-examining before accepting.
Classification and/or Status

Clypeasteroida; Scutellina; Laganiformes; Fibulariidae.

Monotypic.

Remarks

Differs from the type of Fibularia only in being more inflated and subconical in profile. The presence of a weakly defined groove in the frontal ambulacrum also distinguishes it.

Mortensen, T. 1948. A Monograph of the Echinoidea IV.2 Clypeasteroida. C. A. Reitzel, Copenhagen.

Pomel, A. 1888. C. R. Acad. Sci. Paris 106, p. 373.