BOOK IX. Lxxiv. 159-162 



to say, after six months of life they melt invisibly 



back into mud, and again in the waters of spring- 



time are reborn what they were before, equally 



owing to some hidden principle of nature, as it occurs 



every year. Also mussels and scallops are produced Non-sexmi 



by spontaneous generation in sandy waters ; fish with ''^P^odw.non. 



harder shells, Uke the two varieties of pui-ple-fish, 



are generated by a sticky juice hke sahva, as gnats 



are by moisture turning sour ; the anchovy by sea- 



foam groAving warm when rain gets into it ; but fish 



protected by a flinty covering, Uke oysters, are 



generated by rotting mud, or by the foam round 



ships that stay moored for some time, and especiaUy 



round stakes fixed in the ground, and timber. It 



has recently been discovered in oyster-beds that a 



fertiUzing moisture flows out of these fish Uke milk. 



Eels rub against rocks and the scrapings come to Ufe ; 



this is their only way of breeding. DifFerent kinds 



of fish do not mate together, except the skate and 



the ray, the cross between which is Uke a ray in 



front, and bears in Greece a name " derived from the 



names of both parents. 



Some creatures are born at a fixed season of the Breeding- 

 year, water species as weU as those on land : scaUops '^aHow 

 and slugs and leeches in the spring ; these also pass m^uiiic 

 away at a fixed season. Among fish the wolf-fish 

 and the sardine breed twice a year, and so do aU the 

 rock-fish; some breed three times, for instance the 

 herring ; carp six times ; sea-scorpions and sargi 

 twice, in spring and autumn : of the flat fish only the 

 skate twice, in the autiunn and at the setting of the 

 Pleiads ; most fish in the three months of April, 

 May and June ; the stockfish in the autumn, the 

 sargus, the torpedo and the squalus at the season 



273 



