32 



TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



information as to the life-history and habits of the young 

 plaice may be a useful addition to this report. 



The average size at which the female plaice becomes 

 mature in our seas is about 14 to 15 inches ; and if it were 

 possible to so regulate matters, it would be very desirable, 

 in the interests of the fisheries, that each mature plaice 

 should be allowed to spawn at least once before being 

 caught. The spawning in our seas takes place in the 

 early months of the year — a little earlier or a little later, 

 according to the locality and temperature of the season — - 

 but we may say, in general, from January or February to 

 May, with a maximum in March. The fertilised egg is 

 spherical and transparent, floats at the surface of the sea, 



Plaice just hatched 



Fig. 10. 



and measures about l-12th of an inch (1*9 mm.) in 

 diameter. The period that the embryo remains inside the 

 egg-covering also depends, to some extent, upon the 

 temperature of the sea water at the time. It may probably 

 vary from a fortnight to three weeks ; and 17 or 18 days 

 may be taken as an average time. During the last fort- 

 night of this period the young fish may be clearly seen 

 with the microscope inside the egg-covering (see 

 figure W, p. 31), and for the last few days before hatching- 

 it lies coiled up, and occasionally moving, ready to burst 

 through its shell and emerge as a larva. 



When the larval plaice hatches out (see figure 10) it 



