the fragments from a lost Peri Eusebias (On Religion) found by Pitra and Harris. [Philo and the Church Fathers] (p. 92)
Randall Harris for his part says that he "did not think it was worth while to print" these unidentified passages. Yet we can point to works of unknown works of Philo of Alexandria as being available to John of Damascus in the Mar Saba monasteryi in the eighth century. Indeed a pattern of works of Alexandrian origin seem to be emerging - i.e. Philo, Clement, Origen, Eulogius, Theophilus etc.
It is also important to note that critical editions of Clement of Alexandria compare the citation of Clement of Alexandria's known works in John of Damascus with those which survive in our corrupt examplars owing to the fact that these text represent a completely different manuscript tradition. The Mar Saba texts of Clement are now all lost - including the 'letters of Clement of Alexandria.'