Orthonychiidae is an extinct family of fossil sea snails, marine, gastropod molluscs in the clade Cyrtoneritimorpha.
There is an unusually great degree of variability within the shells of species in the genus Orthonychia, but an analysis of this variability has not been done yet (2008).
Genera Genus Orthonychia Hall, 1843Hall J. (1843). "Geology of New York. Part IV, comprising the survey of the fourth geological district". Natural History of New York 4: 1-683. Orthonychia acuta Roemer, 1856 Orthonychia baldwini Rohr et al., 1981 Orthonychia belli Clarke, 1908 Orthonychia bowsheri Yochelson, 1956 Orthonychia chesterense Meek & Worthen, 1866 Orthonychia concavum Hall, 1860 Orthonychia conicum Hall, 1860 Orthonychia conoidea (Goldfuss, 1844) Orthonychia cornuforme (Winchell, 1863) Orthonychia costata (Barrois, 1889) Orthonychia daschi (Rohr & Smith, 1978) Orthonychia dentalium Hall, 1862 Orthonychia enorme (Lindström, 1884) Orthonychia infabricatus Hyde, 1953 Orthonychia marblecreekensis Talent & Philip, 1956 Orthonychia obliquesulata Spitz, 1907 Orthonychia pajerensis Chronic, 1949 Orthonychia parva (Shumard & Swallow, 1858) Orthonychia parvulum Whiteaves, 1892 Orthonychia pentalvea Talent & Philip, 1956 Orthonychia perplexum (Hall, 1879) Orthonychia prosseri Clarke & Swartz, 1913 Orthonychia protei (Oehlert, 1883) Orthonychia puellaris (Whidborne, 1891) Orthonychia quadrangularis (Whidborne, 1891) Orthonychia rostratus (Trenkner, 1867) Orthonychia sciotoensis Hyde, 1953 Orthonychia sileni (Oehlert, 1883) Orthonychia subrectum Hall, 1860 - type species Orthonychia steinbergensis Kegel, 1926 Orthonychia talon Tolmachoff, 1930 Orthonychia tortuosa (Hall, 1860) Orthonychia trirotundolobatum (Talent & Philip, 1956) Orthonychia unguiculata Clarke & Swartz, 1913 Orthonychia variablis Tyler, 1965 Orthonychia vishtytica Saladzius, 1966 Orthonychia vomerium (Winchell, 1863) Orthonychia waverlyensis Hyde, 1953 Orthonychia compressa / Platyceras (Orthonychia) compressum Girty 1910"†Platyceras (Orthonychia) compressum Girty 1910 (snail)". Paleobiology Database, accessed 8 August 2010. Orthonychia ungula / Platyceras (Orthonychia) ungula (Weller, 1906)"†Platyceras (Orthonychia) ungula Weller 1906 (snail)". Paleobiology Database, accessed 8 August 2010.
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