It was found about the middle of the sixteenth century, enclosed in a marble sarcophagus, within a sepulchral chamber under the Monte del Grano, two miles and a half from Rome, on the road to Frascati. It is ornamented with white opaque figures in bas-relief, upon a dark blue transparent ground. The subject has not hitherto received satisfactory elucidation; the design, and more especially the execution, are truly admirable. The whole of the blue ground, or at least the part below the upper welding of the handle, was originally covered with white enamel, out of which the figures have been sculptured, in the style of a cameo, with astonishing skill and labour.* Although there cannot exist any doubt as to the materials of which this vase is composed, it is extraordinary that notwithstanding four authors have agreed in considering it to be stone, all differ as to the kind of stone; Breval regarded it as calcedony; Bartoli, sardonyx; Count Tetzi, amethyst; and De la Chausse, agate. That travellers or authors should have been so ignorant, as to suppose that a natural production could have been hollowed out of the size of the Portland Case seems surpassing strange; nor does it appear less perplexing that each account should differ in the colour and description of stone. The subject of the bas-relief is involved in equal mystery, for as much difference of opinion exists respecting it as of the materials. The fable of Thaddeus and Theseus was considered by some writers to be the subject; Bartoli supposed the group to represent Proserpine and Pluto; Count Tetzi, that it has reference to the birth of Alexander Severus, in whose supposed tomb it was discovered; while