The Echinoid Directory

Labrotaxis Casey, 1960, p. 260

Diagnostic Features
  • Test cordate with deep anterior sulcus with sharp carina. Lower surface flat but with keeled plastron.
  • Apical disc subcentral with four gonopores.
  • Paired ambulacra petaloid with elongate and conjugate pore-pairs. Columns of pore-pairs in anterior petals unequal, the posterior column being 1.5 to 2 times wider than the anterior column.
  • Frontal groove present from apex to peristome; keeled aborally.
  • Peristome oval, typically a little oblique to the anterior.
  • Plastron plating protosternous: labral plate crescentic and extending to meet second sternal plate.
  • Periproct inframarginal, on steeply inclined posterior face.
  • Enlarged primary tubercles line the margin of the anterior sulcus and are also developed adapically and along the posterior interambulacral ridge aborally.
  • No fascioles.
Distribution
Lower Cretaceous (Albian).
Name gender feminine
Type
Labrotaxis cantianus Casey, 1960, p. 261, by original designation
Species Included
  • Casey (1960) also included Holaster latissimus Agassiz, in this genus.
Classification and/or Status

Holasteroida, stem group.

Subjective junior synonym of Pseudholaster Pomel, 1883 (seeSmith & Wright, 2003).

Remarks

Indistinguishable from Pseudholaster Pomel, 1883. Casey's type species is actually a composite of two species (see Smith & Wright, 2003).

Smith, A. B. & Wright, C. W. 2003. British Cretaceous echinoids. Part 7, Atelostomata, 1. Holasteroida. Palaeontographical Society Monographs, London. Pp. 440-568, pls 139-182.