Platyceras mansfieldense (FOSSIL) Tassell, 1977 †
Natirhenia margaritifera (FOSSIL) (d'Archiac & de Verneuil,1842 †)
Cyclonema margaritoides (FOSSIL) (J.J.F. Whiteaves,1897 †)
Cyclonema marylandense (FOSSIL) Prosser & Kindle, 1913 †
Platyceras marylandicum (FOSSIL) A.H. Clarke & Swartz,1913 †
Strophostylus matheri (FOSSIL) J.W. Hall, 1859 †
Cyclonema mediale (FOSSIL) Ulrich & Scofield, 1897 †
Spinyplatyceras milleri (FOSSIL) (Nettelroth, 1889 †)
Ptychospirina mima (FOSSIL) (J. Perner, 1903 †)
Cyclonema minuta (FOSSIL) (J.W. Hall, 1845 †)
Platyceras minutum (FOSSIL) A.C. Chapman, 1916 †
Platyschisma missouriensis (FOSSIL) Weller, 1899 †
Platyostoma modesta (FOSSIL) W.H. Webster, 1906 †
Cyclonema modestum (FOSSIL) C.M. Poulsen, 1974 †
Cyclonema montrealense (FOSSIL) Billings, 1865 †
Palaeocapulus morsei (FOSSIL) Hoare, 2004 †
Platyostoma muitissima (FOSSIL) A.H. Clarke, 1903 †
Barynema multilirata (FOSSIL) (J.W. Hall, 1859 †)
Platyceras multiplicatus (FOSSIL) (Giebel, 1858 †)
Spinyplatyceras multispinosum (FOSSIL) (F.B. Meek, 1873 †)
Platyceras nasutum (FOSSIL) Miller, 1891 †
Platyostoma naticoides (FOSSIL) R. Etheridge jr., 1878 †
Praenatica naticoides (FOSSIL) (F.A. Roemer, 1852 †)
Strophostylus naticoides (FOSSIL) J.W. Hall 1859 †
Lotzia neglecta (FOSSIL) (B. Phillips, 1841 †)
Platyceras nettersheimensis (FOSSIL) Heidelberger, 2003 †
Strophostylus nevadensis (FOSSIL) W.J. Gordon& E.L. Yochelson, 1983 †
Platyceras neverovoensis (FOSSIL) Mazaev, 1996 †
Crossoceras newberryi (FOSSIL) (J.W. Hall, 1860 †)
Cyclonema niagarensis (FOSSIL) Winchell & Marcy, 1866 †
Platyceras niagarensis (FOSSIL) J.W. Hall, 1852 †
Platyostoma niagarensis (FOSSIL) (J.W. Hall, 1852 †)
Platyceras nodosum (FOSSIL) T.A. Conrad, 1841 †
Rhineoderma nodulostriata (FOSSIL) (J.W. Hall, 1856 †)
Cyclonema nodulosum (FOSSIL) Lindström, 1884 †