The Echinoid Directory

Contributed by Andrew Smith, April 2008

Brisaster inaequalis (Forbes, 1846, p. 160)

[= Brissus inaequalis Forbes, 1846, p. 160, pl. 19, fig. 6.
=Brissopsis rana Forbes, 1846, p. 161, pl. 19, fig. 5.]

Diagnostic Features
  • Test with deep and sharply defined frontal groove.
  • Apical disc ethmolytic with three gonopores, no gonopore piercing genital plate 2.
  • Petals narrow, straight, sunken; pore-pairs conjugate with relatively narrow perradial zone between the two columns.  Petals taper distally; no occluded plates at end.
  • Ambulacrum III with enlarged pore-pairs with distinct interporal knob in upper part.
  • Aboral tuberculation fine, unifoprm and dense.
  • Peripetalous fasciole well developed, passing just below ends of petals and indented behin the anterior paired petals by at least two plates.  A narrow lateroanal fasciole branches from this inflexion point and passes beneath the periproct,
Distribution Upper Cretaceous, southern India.
Type Syntype: BMNH E78530.
Classification and/or Status A  species of Brisaster.
Remarks The syntype is too worn to preserve any details of tuberculation or fasciole pattern, and the plastron is damaged.  However, numerous specimens from this region are avalable and some show the fasciole pattern.  Most of Forbes's material came from the Pondicherri region and is Campanian-Maastrichtian in age.

Forbes, E. 1846. Report on the fossil invertebrata from southern India, collected by Mr. Kaye and Mr. Cunliffe. Transactions of the geological Society, London (2) 7, 97-174.