Cythara compacta F. Nordsieck, 1977
Acmaturris comparata (FOSSIL) W.P. Woodring, 1928 †
Eucithara compressicosta (O. Böttger, 1895)
Mangelia compsacosta (FOSSIL) J. Gardner, 1937 †
Marita compta (A. Adams & G.F. Angas,1864)
Heterocithara concinna C. Hedley, 1922
Mangelia concinna A.A. Gould, 1861
Tenaturris concinna (C.B. Adams, 1852)
Propebela concinnula (A.E. Verrill, 1882)
Pseudorhaphitoma confortinii L. Bozzetti, 2007
Mangelia congoensis K.H.J. Thiele, 1925
Eucithara coniformis (L.A. Reeve, 1846)
Eucithara conohelicoides (L.A. Reeve, 1846)
Curtitoma conoidea (G.O. Sars, 1878)
Saccharoturris consentanea (FOSSIL) (R.J.L. Guppy, 1896 †)
Curtitoma contraria A. Bonfitto & M. Morassi,2012
Oenopota convexigyra P. Bouchet & A. Warén,1980
Mangelia coplicata (FOSSIL) Pezant, 1905 †
Mangelia coppingeri E.A. Smith, 1881
Eucithara coronata (R.B. Hinds, 1843)
Eucithara coronata cithara (A.A. Gould, 1851)
Benthomangelia cosibensis (FOSSIL) (M. Yokoyama, 1920 †)
Mangelia costata (T. Pennant, 1777)
Mangelia costata subcostata (FOSSIL) Boettger, 1906 †
Antiguraleus costatus (C. Hedley, 1922)
Mangelia costellaria (FOSSIL) P. Nyst, 1836 †
Leiocithara costellarioides R.N. Kilburn, 1992
Mangelia costulata A. Risso, 1826
Agathotoma coxi (W.G. Fargo, 1953)
Pyrgocythara crassicostata (C.B. Adams, 1850)
Mangelia crebricostata (P.P. Carpenter, 1864)
Kurtzina crossata (W.H. Dall, 1927)
Pseudorhaphitoma crudelis C. Hedley, 1922
Bactrocythara cryera (W.H. Dall, 1927)
Mangelia cryptopleura (FOSSIL) J. Gardner, 1937 †