Du Cange[587] identified the Porta Xylo Kerkou with this gate. But the former was an entrance in the Theodosian lines;[588] it led directly into the city, and was built up in the reign of Isaac Angelus[589]—facts which did not hold true of the Xylo Porta. Furthermore, Ducas expressly distinguishes the two entrances.[590] Or the facts in the case may be stated thus: The Gate of the Xylokerkus was in existence before the erection of the wall in which the Xylo Porta stood; the former entrance being not later than the reign of Anastasius I., in the fifth century, the latter not earlier than the reign of Heraclius, in the seventh century, when the wall on the west of Blachernæ was erected. Therefore the two entrances cannot be the same gate under different names. In Dr. Mordtmann’s opinion,[591] the Postern of Kallinicus (τὸ τῆς Καλλινίκου παραπόρτιον), mentioned by Byzantine writers,[592] was the Xylo Porta under an earlier name. And what is known regarding that postern lends support to this view. Like the Xylo Porta, the Postern of Kallinicus stood near the Church of Blachernæ,[593] and led to the Church of SS. Cosmas and Damianus in the Cosmidion,[594] as well as to the bridge across the head of the Golden Horn.[595] The identity is confirmed by the fact that the bridge to which the road issuing from the Xylo Porta conducted was sometimes called the Bridge of St. Kallinicus, after a church of that dedication in its neighbourhood.[596] The Bridge across the Golden Horn. The earliest mention of a bridge across the Golden Horn is found in the _Notitia_.[597] It was situated in the Fourteenth Region, and, like the bridge across the Tiber, was a wooden structure, “pontem sublicium.” This was superseded by a bridge of stone,[598] which Justinian the Great constructed in 528, “so that one might pass,” as the _Paschal Chronicle_[599] expresses it, “from the opposite side (ἀπὸ τῆς ἀντι πέραν) to the all-happy city.” The new building went by various names in the course of its long history. It was known as the Bridge of Justinian (ἡ Ἰουστινιανοῦ γέφυρα),[600] in honour of its constructor; as the Bridge of St. Kallinicus (ἡ γέφυρα τοῦ ἁγίου Καλλινίκου),[601] after a church dedicated to that saint near its southern end; as the Bridge of St. Panteleemon (ἡ τοῦ ἁγίου Παντελεήμονος γέφυρα),[602] after a church of that name at its northern end; as the Bridge of Camels (ἡ τῆς Καμήλου γέφυρα),[603] on account, probably, of its frequent use by caravans of camels, bringing charcoal to the city; as the Bridge of Blachernæ,[604] from the district in which it stood. Whether it was the bridge of twelve arches near St. Mamas mentioned by the Anonymus and Codinus[605] is uncertain, for we cannot be sure that all references to the Church of St. Mamas allude to the church of that dedication which stood outside the walls of the city, and overlooked the head of the Golden Horn.