A titular suffragan see of Pelusium in Augustamnica Prima
Thennesus, a titular suffragan see of Pelusium in Augustamnica Prima. Cassian (Collat., XI, 1-3) gives a very exact description of the little island which includes this bishopric. Its inhabitants were given solely to commerce owing to the lack of arable land. The bishop of this locality had just died when Cassian arrived there; and they were about to name a successor. In 451 Heron, another of its bishops, was condemned by the Council of Chalcedon for not having anathematized the Patriarch Dioscorus (Mansi, "Concil. coll.", VI, 572; VII, 52). During the eighth century the Patriarch of Antioch, Dionysius of Tell Mahre, landed there (Bar-Hebraeus, "Hist. eccles.", I, 360). About 870 the monk Bernard was well received there by the inhabitants, who were almost all Christians (Tobler and Molinier, "Itinera hierosolymitana", I, 313). Thennesus is also mentioned in a Coptic "Notitia episcopatuum" (Rouge, "Geog. anc. de la Basse Egypte", 156). It is today Tell-Tenis, at the extremity of an island in Lake Menzaleh, near the Suez Canal. There still remain there ruins and tombs of the Roman era.