The Echinoid Directory

• Test low.
• Apical disc about half the test diameter.
• Interambulacra with 6-7 plates in a column. Primary tubercles perforate and non-crenulate. Areoles rather deeply incised.
• Scrobicular tubercles differentiated; extrascrobicular zones hardly developed.
• Weak interradial furrow with obvious pits at triple suture junctions.
• Ambulacra narrow with small, oblique pore-pairs; interporal partition narrow but always present. Single tubercle on each plate.
• Peristome smaller than apical disc; with just 5 or 6 ambulacral plates in a column; interradial plates confined to outer part.
• Primary spines with very short collar and neck; shaft ornamented with fine granules and dense cortical hairs.
• Oral primary spines flattened with serrated edges.

Recent, New Zealand.

Ogmocidaris benhami Mortensen, 1921, p. 148, by original designation.

• Only the type species.

Cidaroida, Cidaridae, Goniocidarinae.

Monotypic.

Distinguished from Ctenocidaridae by having a deep interradial furrow and small globiferous pedicellariae with an end tooth. Ogmocidaris and Austrocidaris have a similar furrow but their peristomial plating is very different. In Ogmocidaris the interradial plates do not reach the adradial margin and there are only about 6 plates in a series. In Austrocidaris interradial plates extend the full radial length of the membrane and there are about twice as many plates in a series.

Mortensen, T, 1921. Vidensk. Medd. 73, pp. 142, 151.

Mortensen, T. 1928. A monograph of the Echinoidea. 1, Cidaroidea. C. A. Reitzel, Copenhagen.

Fell, H. B. 1954. Tertiary and Recent Echinoidea of New Zealand. Cidaridae. New Zealand Geological Survey. Paleontological Bulletin 23, 1-62, pls 1-15.