The same author mentions also a kind of schistos which has no affinity to hæmatites, and to which he gives the name of “anthracites.”[2734] It is a native of Africa, he says, and is of a black colour. When rubbed upon a water-whetstone, it yields a black colour on the side which has adhered to the earth, and, on the opposite side, a saffron tint. He states also that it is a useful ingredient in ophthalmic preparations. CHAP. 39. (21)—AËTITES. TAPHIUSIAN STONE. CALLIMUS. The stone called aëtites[2735] has a great reputation, in consequence of the name which it bears. It is found in the nests of eagles, as already mentioned in our Tenth Book.[2736] There are always two of these stones found together, they say, a male stone and a female; and without them, it is said, the various eagles that we have described would be unable to propagate. Hence it is, too, that the young of the eagle are never more than two in number. There are four varieties of the aëtites: that of Africa is soft and diminutive, and contains in the interior—in its bowels as it were—a sweet, white, argillaceous earth. It is friable, and is generally thought to be of the female sex. The male stone, on the other hand, which is found in Arabia, is hard, and similar to a nut-gall in appearance; or else of a reddish hue, with a hard stone in the interior. The third kind is a stone found in the Isle of Cyprus, and resembles those of Africa in appearance, but is larger and flat, while the others are of a globular form: it contains a sand within, of a pleasing colour, and mixed with small stones; being so soft itself as to admit of being crushed between the fingers. The fourth variety is known as the Taphiusian aëtites, and is found near Leucas,[2737] at Taphiusa, a locality which lies to the right as you sail from Ithaca towards Cape Leucas. It is met with in the beds of rivers there, and is white and round; having another stone in the interior, the name given to which is “callimus:” none of the varieties of aëtites have a smoother surface than this. Attached to pregnant women or to cattle, in the skins of animals that have been sacrificed, these stones act as a preventive of abortion, care being taken not to remove them till the moment of parturition; for otherwise procidence of the uterus is the result. If, on the other hand, they are not removed at the moment when parturition is about to ensue, that operation of Nature cannot be effected. CHAP. 40.—SAMIAN STONE: EIGHT REMEDIES.