1. Some originate in mud and sand: even of those kinds which originate in sexual intercourse and ova, some, they say, have appeared both in other marshy places and in those which once surrounded Cnidus, which became dry under the influence of the dog-star, and all the mud was parched up, but with the first rains the waters returned, and small fish appeared with the return of the waters. This was a kind of cestreus, which originates in coition, about the size of small mænidia,[209] but they had neither ova nor semen. In the Asiatic rivers, which do not flow into the sea, other small fish, of the size of epseti,[210] are produced in the same manner. Some persons say that the cestreus is always produced in this manner, but in this they are mistaken, for both the females are known to have ova and the males semen. But there is some one kind of them which originates in mud and sand. [209] Sardine. [210] Atherine epsetos. 2. It is evident from the following considerations that some of them are of spontaneous growth, and do not originate either in ova or semen. Those which are neither oviparous nor viviparous are all produced either from mud or sand, or from the putrid matter on the surface, as also the foam in sandy places produces the aphya.[211] This aphya never increases in size, and is barren, and as time advances it perishes, and another fry is formed. Wherefore it may be said to be reproduced at every season, except for a short time; for it continues from the autumn arcturus to the spring. This is a proof that it sometimes originates in the soil, for it is not captured by fishermen in cold weather, but on a fine day it may be taken as it comes up from the ground for the sake of the warmth. When they have dragged the ground and scraped up the surface, the fish are more numerous and better. The other aphyæ are inferior, on account of their rapid growth. [211] Melanurus juvenculus. 3. They are found in shady and marshy places, when the earth becomes warm in fine weather, as near the temple of Athene in Salamis, and near the tomb of Themistocles, and near Marathon, for foam is formed in all these places. It makes its appearance in such places, and in fine weather: it appears also at times in seasons of much rain, and when foam is formed of rain water, wherefore also it is called aphrus; and sometimes it is found on the surface of the sea, in fine weather, where it is whirled about, and, like the little maggots in dung, so this is found in the foam which floats on the surface; wherefore also this aphya is carried by the sea in many directions, and it abounds and is captured in the greatest abundance when the season is moist and warm.