The Echinoid Directory

Moira A. Agassiz, 1872, p. 146

[pro Moera Michelin, 1855, p. 246, non Leach, 1814 ]

Diagnostic Features	Test ovate with anterior sulcus; base slightly pointed; inflated in profile. Apical disc ethmolytic, with 2 gonopores, the anterior gonopores missing; posterior genital plates widely separated. Anterior ambulacrum deeply sunken adapically but shallowing by ambitus. Pore-pairs and tube-feet specialized; arranged uniserially. Other ambulacra also deeply sunken, forming slit-like depressions on aboral surface. Periproct small and marginal, on near-vertical truncate face. Subanal region projecting slightly. Peristome large; wider than long; kidney-shaped. Labral plate short and wide; in broad contact with sternal plates; extending to first ambulacral plate only. Sternal plates large and symmetrical. Episternal plates offset and not forming the plastron. Aboral tuberculation fine, uniform and dense. Oral tubercles also dense and uniform in style. Well-developed peripetalous and lateral fascioles. The peripetalous fasciole bounds closely the petals.
Distribution	Miocene to Recent, Indo-Pacific, Caribbean, western Atlantic.
Name gender	feminine
Type	Spatangus atropos Lamarck, 1816, p. 32, by ICZN designation, 1948.
Species Included	M. atropos (Lamarck, 1816); Pleistocene to Recent, east American coast from Brazil to North Carolina, Caribbean. M. clotho Michelin, 1855; Pliocene to Recent, west coast of America from California to Equador. M. lachesinella Mortensen, 1930; Recent, Japan. M. lethe Mortensen, 1930; Recent, Australia. M. stygia Lutken, 1872; Recent, Indo-West Pacific. M. adamthi Clegg, 1933; Miocene Dam Formation, Arabian Peninsula. M. antiqua Duncan & Sladen, 1883; Miocene, Kachh, Pakistan. M. primaeva Duncan & Sladen, 1884; Miocene, Pakistan. M. obesa Nisiyama, 1935; Miocene, Japan and Formosa.
Classification and/or Status	Spatangoida, Paleopneustina, Schizasteridae. Presumed paraphyletic, by exclusion of Moiropsis.
Remarks	Closely related to Moiropsis, which differs in having the frontal groove shorter than the anterior petals. Readily distinguished from other schizasterids by its deeply invaginated petals. Agassiz, A. 1872, in 1872-1874. Revision of the Echini. Memoirs of the Museum of Comparative Zoology at Harvard College, 3: pts. 1-2: i-xii, 1-378, pls 1-49 (1872); pt. 3: 379-628 +1, pls 50-77 (1873); pt. 4: 629-762, pls 78-94 (1874). Mortensen, T. 1951. A monograph of the Echinoidea V. Spatangoida 2. C. A. Reitzel, Copenhagen.