Many fishes pass the summer in the Propontis, and do not enter the Euxine; such, for instance, as the sole,[2351] while on the other hand, the turbot[2352] enters it. The sepia[2353] is not found in this sea, although the loligo[2354] is. Among the rock-fish, the sea-thrush[2355] and the sea-blackbird are wanting, as also purples, though oysters abound here. All these, however, pass the winter in the Ægean Sea; and of those which enter the Euxine, the only ones that do not[2356] return are the trichiæ.[2357]—It will be as well to use the Greek names which most of them bear, seeing that to the same species different countries have given different appellations.—These last, however, are the only ones that enter the river Ister,[2358] and passing along its subterraneous passages, make their way from it to the Adriatic;[2359] and this is the reason why they are to be seen descending into the Euxine Sea, but never in the act of returning from it. The time for taking tunnies is, from the rising of the Vergiliæ[2360] to the setting of Arcturus:[2361] throughout the rest of the winter season, they lie concealed at the bottom of deep creeks, unless they are induced to come out by the warmth of the weather or the full moon. These fish fatten[2362] to such an extraordinary degree as to burst. The longest period of their life[2363] is two years. CHAP. 21.—WHY FISHES LEAP ABOVE THE SURFACE OF THE WATER. There is a little animal,[2364] in appearance like a scorpion, and of the size of a spider.[2365] This creature, by means of its sting, attaches itself below the fin to the tunny and the fish known as the sword-fish[2366] and which often exceeds the dolphin in magnitude, and causes it such excruciating pain, that it will often leap on board of a ship even. Fish will also do the same at other times, when in dread of the violence of other fish, and mullets more especially, which are of such extraordinary swiftness, that they will sometimes leap over a ship, if lying crosswise. CHAP. 22. (16.)—THAT AUGURIES ARE DERIVED FROM FISHES. Auguries are also derived from this department of Nature, and fishes afford presages of coming events. While Augustus[2367] was walking on the sea-shore, during the time of the Sicilian war, a fish leapt out of the sea, and fell at his feet. The diviners, who were consulted, stated that this was a proof that those would fall beneath the feet of Cæsar who at that moment were in possession of the seas—it was just at this time that Sextus Pompeius had adopted[2368] Neptune as his father, so elated was he with his successes by sea. CHAP. 23.—WHAT KINDS OF FISHES HAVE NO MALES.