4. The æthuia and the larus hatch their young among the rocks on the sea-side, and produce two or three, the larus during the summer, and the æthuia at the beginning of the spring, immediately after the equinox; it sets upon its eggs like other birds; neither of these kinds conceal themselves. The halcyon is the rarest of all, for it is only seen at the season of the setting of the pleiades, and at the solstice, and it first appears at seaports, flying as much as round a ship, and immediately vanishing away. Stesichorus also speaks of it in the same manner. 5. The nightingale produces her young at the beginning of summer. She produces five or six eggs. She conceals herself from the autumn to the beginning of spring. Insects copulate and produce their young during the winter whenever the days are fine, and the wind in the south, at least such of them as do not conceal themselves, as the fly and ant. Wild animals produce their young once a year, unless, like the hare, they breed while they are nursing their young. CHAPTER IX. 1. Fish also generally breed once a year, as the chyti. All those which are caught in a net are called chyti; the thynnus, palamis, cestreus, chalais, colias, chromis, psetta, and such like, the labrax is an exception, for this alone of them all breeds twice a year, and the second fry of these are much weaker. The trichias[161] and rock fish breed twice, the trigla is the only one that breeds three times a year. This is shewn by the fry, which appear three times at certain places. [161] Clupea Sprottus. 2. The scorpius breeds twice, and so does the sargus, in spring and autumn, the salpa once only in the spring. The thynnis breeds once, but as some of the fry are produced at first, and others afterwards, it appears to breed twice. The first fry makes its appearance in the month of December, after the solstice, the second in the spring. The male thynnis is different from the female, for the female has a fin under the abdomen, called aphareus, which the male has not. 3. Among the selachea, the rhine alone breeds twice in the year; at the beginning of the autumn, and at the period of the setting of the Pleiades. The young are, however, better in the autumn. At each breeding season it produces seven or eight. Some of the galei, as the asterias, seem to produce their ova twice every month. This arises from all the ova not being perfected at once.