142 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



changing their mode of life from the pelagic larval one, 

 where the food is Copepoda and other surface organisms, 

 to that of the ground-living adult, feeding on shellfish 

 and worms. 



When floating on the surface as eggs, in the 

 embryonic stages and as larvae, they are the natural prey of 

 innumerable organisms around them, from medusae to 

 fishes ; and it cannot be doubted that the destruction must 

 be very great, especially in the younger stages. The post- 

 larval forms seem better able to avoid enemies and to take 

 care of themselves ; while when the metamorphosis 

 has taken place, they are probably safe from many 

 dangers which threatened them in the earlier periods. 

 Consequently, protection in a hatchery must save a very 

 large proportion of the eggs and larvae from what would 

 otherwise be their natural fate. 



During the present hatching season we have set free 

 our plaice larvae when between a week and a fortnight 

 after hatching, our object being to keep them as long as 

 possible so as to protect them from destruction in the sea, 

 but to let them out before the yolk-sac was all absorbed 

 and external food required. No doubt it would be still 

 better if we could safely keep them longer, see them 

 through the period of metamorphosis, and set them free in 

 our bays as young flat-fish. That natural sequel to 

 artificial hatching, viz., rearing the young fish in captivity, 

 will no doubt come ; and we have been experimenting 

 in the matter during the last year by allowing a certain 

 number of the larvae to remain developing in our 

 spawning pond. It is satisfactory to find that these have 

 passed through the post-larval period, have undergone 

 their metamorphosis, and have grown rapidly. Some 

 have already been seen in the pond as fully formed young 

 flat-fish, up to five inches in length. There seems to be 



