Fossarus disciformis Grillo, 1877, [Basis of the current name] References: Bouchet & Warén (1988) Comments: Megalomphalus azonea (Brusina, 1864) may be an older name for this species (Warén & Bouchet 1988).
Fossarus crossei sic, [Not available] References: Jeffreys (1885) s (of Adeorbis depressus) Comments: Misidentification and misspelling of Natica crosseana Weinkauff, 1868 (ex Klecak MS). Klecak distributed material (presumably from Dalmatia) under a manuscript name that was validated as Natica crosseana Weinkauff, 1868 (p. 257). Klecak (1873: 29) treated N. crosseana as a synonym of Fossarus petitianus Tiberi in his catalogue of marine mollusks of Dalmatia. Jeffreys (1885: 41) considered that material from Algeria he had received from Weinkauff labelled as Fossarus crossei was not conspecific with Klecak's material but was instead Adeorbis depressus Seguenza. Dall (1889a: 298) seconded this opinion. Warén & Bouchet (1988: 86) noted that F. petitianus is a synonym of Megalomphalus azonea (Brusina, 1864), and that Brusina's name might also prove to be an older name for Adeorbis depressus (in which case Weinkauff would turn out not to have misidentified his Algerian material after all).
Adeorbis depressus Seguenza, 1874, [Synonym] Range: 34.11°N to 33.63°N; 77.6°W to 76.18°W Depth: 27 to 95 m Maximum Reported Size: 4 mm Distribution: USA: North Carolina References: Dall (1889a) DdNSEW; Warén & Bouchet (1988) s Comments: Primary homonymy of A. depressus A. Adams, 1861, not secondary as stated by Warén & Bouchet (1988: 88), therefore the name is permanently invalid, even though the replacement name Adeorbis seguenzianus Tryon, 1888, is not in use. This species was rejected from the North American fauna by Turgeon et al. (1998: 230) without addressing the status of Dall's records off North Carolina. Although Dall (1889a: 298) placed Adeorbis depressus in Gyrodes, which is now considered a naticid, he was not confused about its identity, comparing it to a set of European species now placed in Megalomphalus. The only difference Dall cited was that American specimens reached twice the size of Mediterranean specimens. Dall's records are therefore accepted, pending further study. Combining Genera: Fossarus Gyrodes
Megalomphalus mercatoris Adam & Knudsen, 1969, [Synonym] References: Warén & Bouchet (1988) s
Megalomphalus seguenzai Cossmann, 1918, [Synonym] References: Warén & Bouchet (1988) s Comments: Unjustifed emendation of Adeorbis seguenzianus.
Adeorbis seguenzianus Tryon, 1888, [Synonym] References: Warén & Bouchet (1988) s Comments: Replacement name for Adeorbis depressus Seguenza, 1874, non A. Adams, 1861.
