B. VI.] THE HISTORY OF ANIMALS. 157 



the return of the waters. This was a kind of cestreus, which 

 originates in coition, about the size of small msenidia, 1 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, 2 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. 



2. It is evident from the following considerations that 

 some of them are of spontaneous growth, and do not origi-" 

 nate either in ova or semen. Those which are neither ovi- 

 parous 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. 3 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 nume- 

 rous and better. The other aphyae are inferior, on account 

 of their rapid growth. 



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. 



4. There is another aphya derived from fish, for that 

 which is called cobitis is derived from small and inferior 



1 Sardine. , 2 Atherine epsetos. 3 Melanurus juvenculua. 



