4. The selache, as being viviparous, are less productive. These are particularly preserved by their large size. The belone is late in producing its young, and many of them are burst by their ova in the act of parturition; for these ova are not so numerous as they are large. They surround the parent as if they were phalangia; for she produces them attached to herself, and if any one touches them they make their escape. The atherina deposits her ova by rubbing her abdomen against the sand. The thynni burst with fat. They live two years. The fishermen argue thus: when the thynnides fail one year, the thynni fail the year after. They appear to be a year older than the pelamus. 5. The thynni and scombri copulate at the end of February, and produce their young at the beginning of June. They produce their ova, as it were, in a purse. The growth of the thynnides is rapid; for when these fish produce their young in the Pontus, they produce from the ovum creatures which some persons call scordylæ, and the Byzantines call auxidæ, because they grow in a few days. They go out in the autumn with the thynnus, and return in the spring as pelamides. Nearly all other fish grow rapidly, but those in the Pontus more rapidly than in other places; for the amiæ there increase visibly every day. It is necessary to remember that the same fish have not in the same place the identical time of coition and gestation, nor the same period of reproduction and completion of their offspring. For those which are called coracini produce their ova at the time of wheat harvest, though, generally speaking, the order of their reproduction is that which I have mentioned. 6. The conger also becomes pregnant, though this circumstance is not equally distinct everywhere on account of its fat; for the organ of reproduction is long, like that of serpents. It becomes distinct, however, when laid upon the fire; for the fat smokes and consumes away, and the ova, when pressed, jump out with a cracking noise. If any person will feel and rub them with the finger, the fat will appear smooth and the ova rough to the touch. Some congers have fat but no ova; and others, on the contrary, have no fat but such ova as I have described. We have now treated of nearly all the oviparous animals, whether furnished with fins, or wings, or feet, and of their sexual intercourse, gestation, development, and such like subjects. CHAPTER XVII. 1. We must now treat of the nature of viviparous animals with feet and of man at this period. We have already treated in general and in particular of their mode of coition. It is common to all animals to be elevated with the desire and pleasure of sexual intercourse. The females become savage when their young are produced, the males at the season of coition; for horses bite each other and drive about and pursue their riders. The wild boars are very savage at this season, although coition renders them weak.