Oysters are of various colours; in Spain they are red, in Illyricum of a tawny hue, and at Circeii[161] black, both in meat and shell. But in every country, those oysters are the most highly esteemed that are compact without being slimy from their secretions, and are remarkable more for their thickness than their breadth. They should never be taken in either muddy or sandy spots, but from a firm, hard bottom; the meat[162] should be compressed, and not of a fleshy consistence; and the oyster should be free from fringed edges, and lying wholly in the cavity of the shell. Persons of experience in these matters add another characteristic; a fine purple thread, they say, should run round the margins of the beard, this being looked upon as a sign of superior quality, and obtaining for them their name of “calliblephara.”[163] Oysters are all the better for travelling and being removed to new waters; thus, for example, the oysters of Brundisium, it is thought, when fed in the waters of Avernus, both retain their own native juices and acquire the flavour of those of Lake Lucrinus.[164] Thus much with reference to the meat of the oyster; we will now turn to the various countries which produce it, so that no coast may be deprived of the honours which properly belong to it. But in giving this description we will speak in the language of another, using the words of a writer who has evinced more careful discernment in treating of this subject than any of the other authors of our day. These then are the words of Mucianus, in reference to the oyster:—“The oysters of Cyzicus[165] are larger than those of Lake Lucrinus,[166] fresher[167] than those of the British coasts,[168] sweeter[169] than those of Medulæ,[170] more tasty[171] than those of Ephesus, more plump than those of Lucus,[172] less slimy than those of Coryphas,[173] more delicate than those of Istria,[174] and whiter than those of Circeii.”[175] For all this, however, it is a fact well ascertained that there are no oysters fresher or more delicate than those of Circeii, last mentioned.