Cythara compacta F. Nordsieck, 1977 Mediterranean Sea
Acmaturris comparata (FOSSIL) W.P. Woodring, 1928 † Jamaica, Saint Thomas
Eucithara compressicosta (O. Böttger, 1895)
Mangelia compsacosta (FOSSIL) J. Gardner, 1937 † Florida, Alum Bluff formation
Marita compta (A. Adams & G.F. Angas,1864) Australia, Yorke Peninsula13,8 mm
Heterocithara concinna C. Hedley, 1922 Queensland
Mangelia concinna A.A. Gould, 1861 Ryukyu Islands
Tenaturris concinna (C.B. Adams, 1852) Pacific Panama
Propebela concinnula (A.E. Verrill, 1882) North Carolina, Cape Lookout6 mm
Pseudorhaphitoma confortinii L. Bozzetti, 2007 Madagascar, Lavanono9 mm
Mangelia congoensis K.H.J. Thiele, 1925
Eucithara coniformis (L.A. Reeve, 1846) Hawaii6 mm
Eucithara conohelicoides (L.A. Reeve, 1846) Philippines, Panay Island16,2 mm
Curtitoma conoidea (G.O. Sars, 1878)
Saccharoturris consentanea (FOSSIL) (R.J.L. Guppy, 1896 †) Jamaica, Saint Thomas
Curtitoma contraria A. Bonfitto & M. Morassi,2012
Oenopota convexigyra P. Bouchet & A. Warén,1980 Indonesia, Flores3,6 mm
Mangelia coplicata (FOSSIL) Pezant, 1905 † France, Paris Basin9 mm
Mangelia coppingeri E.A. Smith, 1881
Eucithara coronata (R.B. Hinds, 1843) Philippines, Olango Island10,2 mm
Eucithara coronata cithara (A.A. Gould, 1851) Fiji Islands10,5 mm
Benthomangelia cosibensis (FOSSIL) (M. Yokoyama, 1920 †) Okinawa18,5 mm
Mangelia costata (T. Pennant, 1777) Turkey, Bozcaada Island4 mm
Mangelia costata subcostata (FOSSIL) Boettger, 1906 † Hungary, Borsodbóta
Antiguraleus costatus (C. Hedley, 1922) South Australia
Mangelia costellaria (FOSSIL) P. Nyst, 1836 † Belgium, Vlaanderen, Limburg
Leiocithara costellarioides R.N. Kilburn, 1992 Park Rynie, Natal, South Africa5 mm
Mangelia costulata A. Risso, 1826 Italy, Cannizzaro13 mm
Agathotoma coxi (W.G. Fargo, 1953) USA, Louisiana
Pyrgocythara crassicostata (C.B. Adams, 1850) Bahamas4,5 mm
Mangelia crebricostata (P.P. Carpenter, 1864) Washington, Neah Bay
Kurtzina crossata (W.H. Dall, 1927) America
Pseudorhaphitoma crudelis C. Hedley, 1922 South Africa, Natal, Durban Bay5 mm
Bactrocythara cryera (W.H. Dall, 1927) Bahamas
Mangelia cryptopleura (FOSSIL) J. Gardner, 1937 † Florida, Alum Bluff formation