The Echinoid Directory

• Test ovate with faint, more or less obliterated, anterior sulcus; posterior face truncate. Test depressed above and below.
• Apical disc ethmolytic with three gonopores (no gonopore in genital plate 2); anterior of centre.
• Anterior ambulacrum non-petaloid, with small pore-pairs; weakly depressed.
• Other ambulacra petaloid aborally and weakly sunken, the posterior being slightly longer than the anterior pair. Petals extending more or less to ambitus; parallel-sided and open distally.
• Peristome D-shaped and downward-facing.
• Labral plate longitudinally elongate and moderately large; extending to third ambulacral plate.
• Plastron narrow with symmetical sternal and episternal plates. Episternal plates not strongly indented by adjacent ambulacral plates and opposite.
• Periproct on posterior truncate face; opening between interambulacral plates 5a/b and 8a/b.
• Bilobed subanal fasciole present; oral band passing midway through plates 5.a.3/5.b.3; aboral portion passing across 5.a.4-6 and 5.b.4-6. Peripetalous fasciole present; near ambitus anteriorly and not indented in lateral interambulacral zones; passing close to ends of petals.
• Aboral tuberculation heterogeneous with larger tubercles set in a groundmass of smaller granules.

Lower Eocene (Upper Auradu Series), Somalia.

Archaechinus auraduensis, Kier, 1957, p. 891, by original designation.

• Only the type species.

Spatangoida, Micrasterina, Macropneustidae.

Monotypic.

Differs from Macropneustes in having three gonopores rather than four.

Kier, P. M. 1957. Tertiary Echinoidea from British Somaliland. Journal of Paleontology 31, 839-902.