The Echinoid Directory

Scrippsechinus Allison, Durham & Mintz, 1967, p. 16

Diagnostic Features
  • Test ovate in outline, hemispherical in profile; no frontal groove. Test relatively thin-shelled.
  • Apical disc ethmolytic with four gonopores; centrally positioned; with large apophysis on interior.
  • Frontal ambulacrum flush. Pore-pairs small and oblique; smaller than those in paired ambulacra; plating uniserial adapically.
  • Paired ambulacra with small, weakly enlarged pore-pairs adapically; flush. Plating uniserial adapically.
  • Peristome large and kidney-shaped; angled obliquely towards the front.
  • Labral plate short and wide; not extending beyond first ambulacral plate. Sternal plates paired and symmetrical. Episternal plates also paired and symmetrical; indented to rear by amb plate 6.
  • Periproct opening inframarginal; bounded on oral side by Iamb plates 5a/b.
  • No fascioles present (possible trace of obliterated subanal fasciole).
  • Aboral tuberculation consisting of small uniform tubercles slightly sunken.
Distribution
Recent, Nasca Ridge, East Pacific.
Name gender masculine
Type
Scrippsechinus fisheri Allison, Durham & Mintz, 1967, p. 16, by original designation.
Species Included
  • Only the type species.
Classification and/or Status

Spatangoida, Micrasterina, Palaeotropidae.

Monotypic.

Remarks

Allison et al. 1967 placed this taxon in the Asterostomatidae due to its lack of fascioles. However, the plastron structure, with ambulacral plate 5 at the rear of the sternal plates and the paired episternal plates that abut at their rear amb plate 6, indicates relationships with Micrasterina. It is very similiar to Palaeobrissus, differing primarily in its more inflated shape and in having ambulacra uniserial adapically.

Allison, E. C., Durham, J. W. & Mintz, L. W. 1967. New Southeast Pacific echinoids. Occasional Papers of the California Academy of Sciences 62, 23 pp.