Where he uses the same form ὄστρειον. But afterwards the form ὄστρεον like ὄρνεον began to be used. Plato, in his Phædrus, says, "bound together like oysters" (ὄστρεον). And in the tenth book of his Politia, he says, "oysters (ὄστρεα) stuck together;" "oysters (ὄστρεα) and seaweed." But the peloris, or giant mussel, were so named from the word ὄστρεα, _vast_. For it is much larger than the cheme, and very different from it. But Aristotle says that they are generated in the sand. And Ion the Chian mentions the chema, in his Epidemiæ, and perhaps the shell-fish got the name of χήμη παρὰ τὸ κεχῃνέναι, from opening their mouths." 45. But concerning the oysters which are grown in the Indian Ocean; (for it is not unreasonable to speak of them, on account of the use of pearls;) Theophrastus speaks in his treatise on Precious Stones, and says, "But among the stones which are much admired is that which is called the pearl, being transparent in its character; and they make very expensive necklaces of them. They are found in an oyster which is something like the pinna, only less. And in size the pearl resembles a large fish's eye." Androsthenes, too, in his Voyage along the Coast of India, writes in these terms--"But of strombi, and chærini, and other shell-fish, there are many different varieties, and they are very different from the shell-fish which we have. And they have the purple-fish, and a great multitude of other kinds of oysters. There is also one kind which is peculiar to those seas, which the natives call the berberi, from which the precious stone called the pearl comes. And this pearl is very expensive in Asia, being sold in Persia and the inland countries for its weight in gold. And the appearance of the oyster which contains it is much the same as that of the cteis oyster, only its shell is not indented, but smooth and shaggy. And it has not two ears as the cteis oyster has, but only one. The stone is engendered in the flesh of the oyster, just as the measles are in pork. And it is of a very golden colour, so as not easily to be distinguished from gold when it is put by the side of it; but some pearls are of a silvery appearance, and some are completely white like the eyes of fish. But Chares of Mitylene, in the seventh book of his Histories of Alexander, says--"There is caught in the Indian sea, and also off the coast of Armenia, and Persia, and Susiana, and Babylonia, a fish very like an oyster; and it is large and oblong, containing within the shell flesh which is plentiful and white, and very fragrant, from which the men pick out white bones which they call the pearl. And they make of them necklaces and chains for the hands and feet, of which the Persians are very fond, as are the Medes and all Asiatics, esteeming them as much more valuable than golden ornaments."