136 THE COMMERCIAL SEA FISHES OF 



exclusively took males, whereas the floating-nets secured 

 females. The ova was found to float on the sea, unless the 

 specific gravity of the latter was altered by the admixture 

 of rain or river water, as well as on the death of the 

 embryo, when they sank. The egg floats, due to contain- 

 ing a fine globule of oil, while its heaviest part is where the 

 micropyle exists, and which is consequently turned down- 

 wards or towards the ascending milt. Hatching occurred 

 on the eighteenth day, while in America it was found to 

 take place between the thirteenth and fiftieth days, accord- 

 ing to the heat of the water. The floating eggs and fry 

 are liable to be blown in shore, or destroyed by the action 

 of wind and waves. Several millions of the eggs of this 

 fish have been deposited and hatched in the outer harbour 

 of Gloucester, U.S., in the hopes of raising a local supply, 

 for the water there is too warm for them to naturally seek 

 that locality. 



Life History. The young fish, according to Sar's inves- 

 tigations, at first, or before the umbilical bag has become 

 absorbed, are most helpless beings, floating on the surface, 

 and tossed about by winds and waves. As soon as this 

 sac is absorbed they seek deeper water, where the sea is 

 more quiescent, feeding upon small transparent crustaceans, 

 as " herring food," Calamus finmarchicus and Temora longi- 

 cornis. By the end of the summer, and when about an 

 inch in length, they go more inshore, first finding shelter 

 each under a medusa, Cyanea capillata, where they appear 

 to feed upon the minute animals which constitute the food 

 of this Discophora, and which are stupefied by its numerous 

 poisonous threads, stretching out in all directions. As a 

 return, the young cod-fish consumes a small parasitic crus- 

 tacean, Hyperia, which clings to the medusa by aid of its 

 .sharp claws, and even eats deeply into its jelly-like body. 



