8. At the season of sexual intercourse, the seminal ducts of the male are full of fluid, so that a white matter escapes when they are pressed. These passages are divided, and originate in the diaphragm and the large vein: at the same season the passages of the male are conspicuous, and may be compared with the uterus of the female. When it is not the season of sexual intercourse, they are less conspicuous, from not being in use. In some fish, and sometimes, they are not visible at all, as it was remarked of the testicles of birds. The seminal and uterine passages are different in other respects also, and because those of the male are attached to the loins, those of the female are easily moved, and enclosed in a thin membrane. The nature of the passages of the male may be seen in works on anatomy. 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. CHAPTER XI. 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.