Contributed by Jenna Sullivan, May 2007
[Hemiaster cubicus Desor, in Agassiz & Desor, 1847]
|Diagnostic Features||A Mecaster with long, sub-equal petals reaching about three-quarters of the way to the ambitus. Apical disc sub-central; genital plate 2 separating the posterior paired genital plates but not the posterior ocular plates. Peristome very far forward, directed anteriorly and largely covered by the labrum in oral view. Labral plate very long and narrow. (from Smith et al., 1989, p. 64)|
|Distribution||Very common in the Cenomanian of Egypt and Israel.|
|Classification and/or Status||Species of Mecaster|
|Remarks||M. cubicus is a distinctive species because of its long, sub-equal petals, and very anterior and forward-pointing peristome that, in oral view, is largely hidden from sight. The extreme length of the labral plate is also unusual. No other species of Mecaster or Hemiaster can be confused. (Smith et al., 1989, p. 64)
Agassiz, L. & Desor, E. 1847. Catalogue raisonne des familles, des genres et des especes de la classe des echinodermes (1). Annales des Sciences Naturelles, 3e serie, Zoologie. 8, 5-35.
Smith, A.B., M.D. Simmons & A. Racey. 1989. Cenomanian echinoids, larger foraminifera and calcareous algae from the Natih Formation, central Oman Mountains. Cretaceous Research. 11, 29-69.