THE FLOUNDER FAMILY. 381 



will be seen by a careful comparison of the data given below 

 with the preceding account of the plaice. 



The flounder is peculiar in that it appears to arrive at 

 sexual maturity whilst still very small and, one would naturally 

 conclude, very young. Artificial fertilization has been suc- 

 cessfully effected at St Andrews between a female 7 inches 

 long and a male 4J inches long; and we must add to this 

 that the male in this species, in accordance with the general 

 rule, is smaller than the female, so that we may reasonably 

 suppose that many male flounders come to sexual maturity 

 when less than 4|- inches in length. The mature female carries 

 a greater number of eggs than any other pleuronectid, so far 

 as is known, averaging from 400,000 to 1,200,000. The eggs 

 are also very small, about '038 inch (•95 mm.) diameter, are 

 pelagic and without an oil-globule. 



The size of the eggs and the great number discharged by 

 the female, or in other words the ' exceptional fecundity,' may 

 possibly be factors in causing the flounder to be an exception 

 to all other pleuronectids in that the females are less numerous 

 than the males. This preponderance in numbers of the male 

 sex is usually found only in species which have a demersal 

 spawning-habit, whereas the opposite relation holds amongst 

 those having pelagic eggs. These facts are sometimes ex- 

 plained by the lesser chances of fertilization amongst demersal 

 eggs, because they are isolated in masses and the spermatozoa 

 are extruded directly upon them by the males. 



The disparity in size between the sexes of the flounder is 

 also a feature found in all the pleuronectids or flat-fishes, the 

 culminating point in this character being reached by the long- 

 rough dab, in which fish the female is often three times the 

 length of the male. 



The eggs of the flounder (fig. 2, p. 31) are found in greatest 

 abundance during the months of March, April, May and June, 

 but they may also occur as early as February and as late as 

 mid-July. 



In the Trawling Report of 1884 it was shown that spawning 

 flounders did not occur on the E. coast of Scotland at a greater 

 depth than 30 fathoms, and that, in St Andrews Bay, the 



