The Echinoid Directory

Contributed by Andrew Smith, November 2011

Cagaster Nisiyama, 1968, p. 248

Diagnostic Features
  • Test high, angular with shallow anterior notch
  • Apical disc subcentral, ethmolytic with three gonopores (genital plate 2 lacking a gonopore)
  • Ambulacrum III in shallow, broad groove adapically; pore-pairs uniserial, small the two pores separated by a small granule
  • Paired ambulacra petaloid; anterior petals only very slightly depressed and open distally; posterior petals shorter, slightly depressed and closed distally.  Pore pairs in petals slit-like
  • Peristome damaged, rather large. Well developed phyllode zones
  • Labral plate apparently short and borad (damaged); not extending beyond first ambulacral plate.  Sternal plates wide and fully tuberculate; hardly indented to the rear.  Episternal plates offset.
  • Interambulacral zones 1 and 4 amphiplacous
  • Peripetalous fasciole strongly indented behind anterior petals; passing a little below the ends of the anterior petals; lateroanal fasciole developed.
Distribution Miocene, Japan
Type Schizaster recticanalis Yoshiwara, 1899, p. 2, by original designation.
Species Included One other unnamed species was included by Nisiyama (1966)
Classification and/or Status

Irregularia, Spatangoida, Paleopneustina, Prenasteridae?


Remarks Nisiyama (1968) compared this with Brisaster which also has 3 gonopores, differentiating it on its shallower anterior groove and better developed latero-anal fasciole.  It is described as having the peripetalous fasciole passing a short distance below the anterior petals and seems also to have it crossing plate 4 in the anterior interambulacra.  This suggests closer affinities with Tripylus, which also has three gonopores.  It differs from Tipylus in having shallower petals and a marked difference in the lengths of the anterior and posterior pairs of petals.

Nisiyama, S. 1968. The echinoid fauna from Japan and adjacent regions. Part II. Palaeontological Society of Japan Special Papers 13, 1-491, pls 19-30.