THE FLOUNDER FAMILY. 375 



which will be seen to be only -^ inch less than the diameter of 

 the flounder's egg, a difference which is well within the limits of 

 variation in the size of pelagic eggs. Neither egg having an oil- 

 globule it is often hard to distinguish them at an early stage. 



The spawning-period commences in the month of March 

 (Canu says February for the coast of France, and Smitt gives 

 April to June in Sweden^), is at its height in April, and may 

 continue to the middle of June. The spawning dab carries a 

 smaller number of eggs than most pleuronectids and is one of 

 the least prolific of the flat-fishes. The male is, as a rule, rather 

 smaller than the female, though disparity of size between the 

 sexes is not so marked as in the case of the long-rough dab : 

 the males are also in a marked minority. In its spawning- 

 season this fish appears mostly to be found beyond the three- 

 mile limit, but spawning females undoubtedly do occur 

 within the territorial waters, so that the dab does not exhibit 

 such a strongly marked migratory instinct as, for instance, the 

 plaice. The occurrence of dabs of all sizes far from land, as 

 pointed out in the Trawling Report of 1884, shows that many 

 are reared on the ground inhabited by their parents. In respect 

 to its spawning, the dab may perhaps be regarded as intermediate 

 in character between the plaice and the flounder. The plaice 

 migrates well offshore in the adult condition, whilst the dab 

 does not do so to such an extent (spawning dabs are found 

 in the three-mile limit, but spawning plaice are not), whilst 

 the flounders migrate only to such an extent as to leave the 

 fresh or brackish water and deposit their eggs at a safe distance 

 from the shore. 



A series at St Andrews Laboratory were fertilized at the 

 end of April and the larvae, measuring a little over 2 mm., 

 emerged in twelve days, whilst others again in early June were 

 hatched in seven days, as Canu recently found them do on the 

 French coast in March and April. 



Following out the stages in the first series, bright yellow 



round chromatophores make their appearance on the seventh 



day, scattered over the head dorsally and upon the tail. All 



over the yolk-surface are a number of fine strands, giving 



1 Scand. Fishes, 390. 



