4. Some fish produce ova at all seasons of the year, as the muræna: for this fish produces many ova, and the fry rapidly increase in size, as do those also of the hippurus,[162] for these, from being very small, rapidly increase to a great size; but the muræna produces young at all seasons, the hippurus in the spring. The smyrus differs from the muræna, for the muræna is throughout variegated and weak. The smyrus is of one colour, and strong; its colour is that of the pine tree, and it has teeth both internally and externally. They say that these are the male and the female, as in others. These creatures go upon the land, and are often taken. [162] Coryphœna hippurus. 5. The growth of all fish is rapid, and not the least so in the coracinus among small fish. It breeds near the land, in thick places full of seaweed. The orphos also grows rapidly. The pelamis and thynnus breed in Pontus, and nowhere else. The cestreus, chrysophrys, and labrax, breed near the mouths of rivers. The orcynes and scorpides, and many other kinds, in the sea. 6. Most fish breed in March, April, and May; a few in the autumn, as the salpe, sargus, and all the others of this kind a little before the autumnal equinox; and the narce and rhine also. Some breed in the winter and summer, as I before observed, as the labrax, cestreus, and belona in the winter; the thynnis in June, about the summer solstice: it produces, as it were, a bag, containing many minute ova. The rhyas also breeds in the summer. The chelones among the cestræi begin to breed in the month of December, and so does the sargus, the myxon, as it is called, and the cephalus. They go with young thirty days. Some of the cestrei do not originate in coition, but are produced from mud and sand. 7. The greater number of them contain ova in the spring, but some, as I observed, in the summer, autumn, and winter. But this does not take place in all alike, nor singly, nor in every kind, as it does in most fish which produce their young in the spring: nor do they produce as many ova at other seasons. But it must not escape our notice, that as different countries make a great difference in plants and animals, not only in the habit of their body, but also in the frequency of their sexual intercourse and production of young; so different localities make a great difference in fish, not only in their size, and habit of their body, but in their young, and the frequency or rarity of their sexual intercourse, and of their offspring in this place or that. CHAPTER X.