210 SALT-WATER FISHES 



Pacific seaboard, where it was naturally wanting. Artificial 

 culture of shad, it Is true, has been practised in European 

 countries {e.g. on the Seine, at Elboeuf), but on a smaller scale 

 than in the United States. 



The eggs of the shad sink (in fresh water), but they lie 

 separately on the bottom, and are not adhesive, like the 

 demersal eggs of the herring. (The eggs of the American shad 

 \Alosa sapidissima\ are only a little heavier than the fresh 

 water, and hang suspended a little above the bottom.) 



Both species of shad appear to spawn in early summer, 

 between May and July, the twaite possibly a little earlier 

 than the other. The eggs, which measure when first deposited 

 about 5^ in., are reticulated, like those of the pilchard, 

 but have no oil-globule. In a temperature of 66° they hatch 

 on the fourth day, and the newly hatched larva of the twaite 

 measures rather less than \ in. 



There is no comparison between the eggs and larvas of the 

 shad and salmon. The salmon deposits in a gravelly furrow 

 eggs that measure approximately \ in. and that have many 

 small oil-globules, and they take, under the most favour- 

 able circumstances, thirty-five days to hatch, so that, before 

 emerging from the egg, the larva is already far more advanced 

 towards the adult stage. 



