362 THE FLOUNDER FAMILY. 



in the anal fin^- The grey colour, the dark brown and red 

 spots, deeper form of the body and the shorter peduncle of 

 the tail, the length of the base of the anal fin (more than 

 half that of the body) are points given by the authors of 

 the Scandinavian Fishes as distinctive. 



The young plaice from an inch upwards are very abundant 

 in shallow sandy bays and immense quantities of them are 

 caught in shrimp-nets. As they grow older and larger they 

 move further and further out to sea, so that few over 11 

 inches in length are found within the three-mile limit. This 

 regular distribution and correspondence between size and 

 distance from the shore ^ is ^ also found in some other pleuro- 

 nectids and, although it is probably a habit beneficial to the 

 species under natural conditions, yet it exposes their youngest 

 stages to destruction in enormous numbers by shrimpers and 

 others. 



The plaice arrives at a state of maturity when at an average 

 length of about 12 inches (more off the Scotch coast) and is 

 then found in the deeper waters. Fulton gives the results of a 

 series of experiments conducted by means of marking a great 

 number of plaice and setting them free, which tend to confirm 

 the opinions which had already been expressed by one of us 

 with regard to the migrations and life-habitat of the plaice. 

 He summarises his conclusions, based upon his own experiments 

 and the former operations already referred to, as follows : 



1. "Plaice tend to remain within the inshore waters during 

 the period of immaturity.'' 



2. " Whilst they may travel 20 miles or more in about a 

 year, their movement is, as a rule, slow." 



3. "In the areas investigated, their movement is in a 

 definite direction, i.e. inwards along the south shore of the 

 Frith of Forth in a westerly direction, then outwards and 

 eastwards along the northern shore, and this general direction 

 is continued round St Andrews Bay towards the north." 



" These results," he remarks, " are in agreement with other 

 investigations of the ' Garland ' into the distribution of immature 



1 Petersen, Danish Biol. Stat. Report, 1894. 



■" First clearly pointed out in the Traioling Report of 1884. 



