Strougo, A. & Elattaar, A. A. (2012): Restudy of the Eocene echinoid Schizaster vicinalis var. Libycus Fourtau, 1908 and Biostratigraphic evaluation of the species of Schizaster in the Mokattamian Stage (Middle and Late Eocene) of Egypt. Egyptian Journal of Paleontology, Vol. 12, pp. 1-16, pl.1, 2, 1 text-fig.

ABSTRACT
Schizaster vicinalis var. libycus Fourtau, 1908 differs from true vicinalis by a number
of important characters and should be treated as a separate species, here called
Schizaster (Paraster) libycus. Contrary to previous belief there is no unequivocal evidence
for the occurrence of Schizaster vicinalis in the Mokattamian rocks of Egypt; Egyptian
forms assigned to this species need critical revision. As of today, S. (P.) libycus appears to
be known only from the topmost part of the ElGharaq and Gehannam Formations at Wadi
Hitan where it characterizes the base of division MK8 which is correlated to the base of the
Priabonian. Of the 24 specific names placed under Schizaster in the literature of the
Mokattamian echinoids 8 are either junior homonyms, or objective or subjective synonyms.
In the remaining 16 species, only 9 are of widespread occurrence and/or characterized well
enough to be usefully applied in stratigraphic correlation.