366 THE FLOUNDER FAMILY. 



The next point which demands our attention is the question 

 of the rate of growth. The approximate growth-rate during the 

 first year has been recently worked out by one of us according 

 to the principles which are explained at length in the chapter 

 on Rate of Growth, to which reference should be also made for 

 the general remarks upon the growth-rate of pleuronectids. We 

 may note that the average length of a plaice eight months old 

 is three inches, and that this is increased to 4-|- inches by the 

 completion of the year, a six-inches plaice, further, being 

 usually about 16 months old. Throughout the second summer 

 the growth is very rapid and may perhaps result, at 1 year and 

 9 months, in an average length of some 10 to 11 inches. 



There appears to be a consensus of opinion that by the 

 following spring, namely in the third year, at an average length 

 of 12 inches, the plaice arrives at maturity and reproduces its 

 kind. Growth continues, however, and it is not uncommon to 

 find plaice of 28 inches upon the east coast. According to 

 Cunningham's observations, the plaice of the south coast of 

 Britain are a smaller kind and reach maturity before attaining 

 so great a length. 



THE LEMON-DAB. (Pleuronectes microcephalies, Donov.) 



The pelagic eggs of this species first came under observation 

 in August 1884, when ripe females were procured off the Forth 

 during the Trawling Expeditions 1 . Considerable latitude, how- 

 ever, must be given in regard to the spawning-period, since in 

 the south it is much earlier than in the north. Thus Couch says 

 it is prepared for spawning early in February. Parnell, again, 

 thought it shed its eggs during the month of April, after which 

 it retires to rocky ground, where it generally remains till the 

 commencement of the following year. He thus connected the 

 fish with a migratory instinct during the spawning-season. 

 Day gives May and June as the spawning-period. At Plymouth, 

 Cunningham found pelagic eggs in March, April and May, as well 

 as hatched the larvas from artificially impregnated eggs. Holt 

 found the eggs in April, May and June on the west coast of 

 1 W. C. M., Trawling Report, p. 363. 



