9. The selachea become pregnant again while with young, and the period of gestation is six months. Among the galei, the asterias produces young the oftenest; for it produces twice in a month: it begins to copulate in the month of September. All the other galei except the scylia produce twice in the year; the scylia but once. Some of them have their young in the spring. The rhine produces its first brood in the spring, and its last in the autumn, near the winter season, and the setting of the Pleiades. The second fry are the most numerous. The narca produces its young in the autumn. The selache descend from the ocean and deep water to the shore, to produce their young, both for the sake of the warmth, and care of their offspring.
10. No other fish but the rhine and the batos have ever been observed to unite with others not of their own kind, but there is a fish called the rhinobatus, which has the head and upper part of the rhine, and the lower part like the batus, as it were made up of both. The galei and the galeoeides, as the alopex, dog-fish, and the flat fish, as the narce batos, leiobatos and trygon, are in this manner ovoviparous.
1. The dolphin, whale, and other cetacea which have a blow-hole but no gills, are viviparous, and so are the pristis and the bos. For none of these have an ovum, but a proper fœtus, from which, when perfected, an animal is developed, as in man and the viviparous quadrupeds. The dolphin usually produces one, and sometimes two young ones. The whale generally and usually produces two and sometimes one. The phocæna is similar to the dolphin, for it is like a small dolphin. It is produced in the Pontus. In some respects the phocæna differs from the dolphin, for its size is smaller, it is wider in the back, and its colour is blue. Many persons say that the phocæna is a kind of dolphin.
2. All these creatures which have a blow-hole, breathe and inhale air; and the dolphin has been observed while asleep with the muzzle above the water, and it snores in its sleep. The dolphin and phocæna give milk and suckle their young. They also receive their young into themselves. The growth of the young dolphins is rapid, for they attain their full size in ten years. The female is pregnant for ten months. The dolphin produces her young in the summer-time, and at no other season. They seem also to disappear for thirty days during the season of the dog-star. The young follow their dam for a long while, and it is an animal much attached to its offspring. It lives many years; for some have been known to live twenty-five or thirty years; for fishermen have marked them by cutting their tails and then giving them their liberty. In this way their age was known.