Delbrueck, l.c., pp. 50, 59, does prove that there is no reason why λιθοστρωτον can not mean a mosaic floor of colored marble, but he forgets comparisons with the date of other Roman mosaics, and that Pliny would not have missed the opportunity of describing such wonderful mosaics as the two in Præneste. Marucchi, Bull. Com., 32 (1904), p. 251 goes far afield in his Isityches (Isis-Fortuna) quest, and gets no results.
The latest discussion of the subject was a joint debate held under the auspices of the Associazione Archeologica di Palestrina between Professors Marucchi and Vaglieri, which is published thus far only in the daily papers, the Corriere D'Italia of Oct. 2, 1907, and taken up in an article by Attilio Rossi in La Tribuna of October 11, 1907. Vaglieri, in the newspaper article quoted, holds that the mosaic is the work of Claudius Ælianus, who lived in the latter half of the second century A.D. Marucchi, in the same place, says that in the porticoes of the upper temple are traces of mosaic which he attributes to the gift of Sulla mentioned by Pliny XXXVI, 189, but in urging this he must shift delubrum Fortunæ to the Cortina terrace and that is entirely impossible.
I may say that a careful study and a long paper on the Barberini mosaic has just been written by Cav. Francesco Coltellacci, Segretario Comunale di Palestrina, which I had the privilege of reading in manuscript.
For the many opinions as to the subject of the mosaic, see Marucchi, Guida Arch., p. 75.
This has been supposed to be a villa of Hadrian's because the Braschi Antinoüs was found here, and because we find bricks in the walls with stamps which date from Hadrian's time. But the best proof that this building, which is under the modern cemetery, is Hadrian's, is that the measurements of the walls are the same as those in his villa below Tibur. Dr. Van Deman, of the American School in Rome, spent two days with me in going over this building and comparing measurements with the villa at Tibur. I shall publish a plan of the villa in the near future. See Fernique, Étude sur Préneste, p. 120, for a meagre description of the villa.