The Echinoid Directory

• Test ovate without anterior sulcus or with slight depression only; flat on oral surface and arched aborally, with keeled posterior interambulacrum.
• Apical disc ethmolytic, with 3 gonopores; genital plate 2 projects behind the posterior oculars.
• Anterior ambulacrum narrow; pore-pairs small, simple isopores.
• Other ambulacra petaloid and flush; closed distally without occluded plates.
• Anterior paired petals with pore-pairs in anterior column rudimentary except distally.
• Periproct on short truncate face; deeply invaginated in type species, but only weakly sunken in other species.
• Peristome wider than long; kidney-shaped. Phyllodes inconspicuous.
• Labral plate longitudinally elongate; only just contacting sternal plates; extending to second ambulacral plate.
• Paired sternal plates long and narrow with tuberculation confined to posterior. Episternal plates contracting posteriorly.
• Aboral surface with small uniform tuberculation. In some species a few primary tubercles near the ambitus in interambulacra 1 and 4 (with sunken areoles).
• Subanal fasciole present, shield-shaped.

Recent, Indo-Pacific.

Maretia alta Agassiz, 1863, p. 360, by original designation.

• P. alta (Agassiz, 1863); Recent, Indo-Pacific.
• P. tylota (Clark, 1917); Recent, Philippines.
• P. laevis (Clark, 1917); Recent, Gulf of California.
• P. oblonga Mortensen, 1950; Recent, Galapagos Islands.
• P. interrupta (Studer, 1880); Recent, Australia.

Spatangoida, Micrasterina, Maretiidae.

Subjective junior synonym of Nacospatangus Agassiz, 1873.

Differs from Nacospatangus in having the anterior series of pore-pairs in the frontal petals more reduced adapically.

Koehler, R. 1914. Echinoderma of the Indian Museum, VIII, Echinoidea (i) Spatangides. Echinides du Musee Indien a Calcutta; 257 pp., 20 pls.

Mortensen, T. 1951. A monograph of the Echinoidea. V. Spatangoida 2. C. A. Reitzel, Copenhagen.