CABILONENSIS (Chalon-sur-Saône - Saône-et-Loire)Mentioned in the middle of fifth century.
CAMERACENSIS (Cambrai - Nord)Created at the end of the sixth century by the transfer of the See from Arras.
CARCASSONENSIS (Carcassonne - Aude)Mentioned in the sixth century.
CARNOTENSIS (Chartres - Eure-et-Loire)Created in the fourth century.
CARPENTORATENSIS (Carpentras - Vaucluse)Created in the fifth century, transfered in the sixth century to Venasque, reestablished in the seventh century at Carpentras.
CASTRENSIS (Castres - Tarn)Created en 1317 by the division of the diocese of Albi.
CATHALAUNENSIS (Châlons-sur-Marne - Marne)Attested in at the beginning of the fourth century.
CATURCENSIS (Cahors - Lot)Probably existing in the third century.
CAVALLICENSIS (Cavaillon - Vaucluse)Attested at the end of the fourth century.
CENOMANENSIS (Le Mans - Sarthe)Created in the fifth century.
CLAROMONTENSIS (Clermont-Ferrand - Puy-de-Dôme)Attested at the beginning of the fourth century.
CONDOMIENSIS (Condom - Gers)Founded in 1317, with a diocese detached from Agen.
CONSERANENSIS (pays de Couserans Saint-Lizier - Ariège)Attested in the sixth century.
CONSTANTIENSIS (Coutances - Manche)Attested in the sixth century.
CONVENARUM (Saint-Bertrand-de-Comminges - Haute-Garonne)Mentioned in the sixth century (but probably discontinuous until the middle of the eleventh century).
CORISOPITENSIS (Quimper - Finistère)Probably created in the fifth century.