i.e.Eusebius of Cæsarea, the historian, so called to distinguish him from his namesake of Nicomedia.  cf. Theodoret, Ecc. Hist. i. 1.  The work is not extant.  It may be that mentioned by Eusebius in his Præp. Evang. vii. 8, 20 under the title of περὶ τῆς τῶν παλαιῶν ἀνδρῶν πολυπαιδίας.