Boethius adds something further to this subject of decoration, when he says, in his book on _Consolation_, “The walls were decorated with ivory and glass.” Does he mean the walls of the room itself? It would seem so, for the bookcases or shelves were not placed against the walls, in which case the ornamentation of the latter would not have been seen, but were set out in the room, just as they are in most public libraries to-day. Glass cut in squares, circles, ovals, and rhomboids was used like marble tiles, to ornament the walls, though oftener the arches and the ceilings. Pliny says in his _Natural History_, book XXXVI, “Tiles made of earth they transformed into glass and put on the arches; and this is a recent invention.” It was, then, still a novelty in the time of Nero and Seneca. Yet Seneca speaks of it as a common thing, in letter LXXXVI, on baths, where he says, “Unless the arch is covered with glass.” On this point consult my work on the baths of the Romans. That it was also used on the walls, Vopiscus, as well as Boethius, shows when he says in speaking of Firmus, “The house appears to have been covered over with squares of glass, with bitumen and other material between the squares.” I think the bitumen was here used to fasten the squares of glass to the wall, and not to join them to each other. The joints between the pieces of glass were more appropriately covered with ivory, as Boethius seems to say they were. Ivory was placed also on the bookcases themselves; whence the phrase, “ivory library,” in the _Pandects_. Seneca mentions bookcases made of cedar and ivory. Common sense and the general fitness of the thing of course make it plain that there were bookcases in libraries; I would add the fact that the cases were numbered. Vopiscus so indicates when he says, “The Ulpian library has the elephant book in the sixth case.” Whether by “elephant” he means made of ivory or of the skin of an elephant, I cannot say. The old scholiast in commenting on this phrase, from Juvenal, “Hic libros dabit et forulos” (This one will furnish you with books and cases), gives as an equivalent phrase, “Armaria, bibliotheca” (A library and the books in it). I think the word _foruli_ (pigeon-holes), as here used, properly means either compartments in the shelves, “nests” for the books, following Martial’s use of the word; or, in Seneca’s use of it, separate little cases for them. Sidonius speaks of these cases and of other things found in libraries. “Here,” he says, “is an astonishing number of books and you would think yourself in a library and could see the shelves (_plutei_) of the grammarians; or the seats (_cunei_) of Athenaeus; or the lofty bookcases (_armaria_) of the booksellers.” _Plutei_ are the sloping tables on which books were placed for reading; _cunei_, the rows of seats, as explained in Athenaeus; and _armaria_, bookcases, generally wide and tall, as I have shown. These last Cicero seems to call _pegmata_ in a letter to Atticus.