256 BRITISH FRESHWATER FISHES 



the upper eye has come only on to the upper edge 

 of the head, so that the anterior extension of the 

 dorsal fin has been unable to join the head above 

 the eye, as is shown in the example figured 

 (PL XXXVI). Albinos, quite white and with 

 pink eyes, have sometimes been captured, and also 

 partial albinos, rosy, with a few dark spots. 



The Flounder attains a length of about 1 8 inches ; 

 it is common all round Europe. During the 

 summer it lives in shallow water near the shores, 

 especially where the bottom is sandy ; it also 

 frequents estuaries, and in our islands ascends all 

 suitable rivers, usually as far as the first falls which 

 bar its progress. Thus it formerly ascended the 

 Severn to Shrewsbury, but is now unable to get 

 beyond the weirs which have been constructed 

 near Gloucester. It is a sluggish fish, usually 

 lying partly buried in the sand, sometimes with 

 only the eyes exposed ; when it swims it progresses 

 chiefly by means of undulating movements of the 

 dorsal and anal fins ; but it will often take a jump 

 from one place to another, if the expression is 

 permissible when the fish does not leave the water, 

 lifting itself from the bottom by a stroke of the tail. 

 It feeds on worms, little fish, etc., but especially on 

 crustaceans and molluscs, the pharyngeal teeth being 

 strong and obtuse, well adapted for crushing shells. 



The spawning season is usually in March and 

 April, but varies from January to June; at this 

 season the Flounders assemble in the sea in 

 moderately deep water, usually between 5 and 30 

 fathoms ; the eggs are very numerous ; they are 

 buoyant and float at the surface, and are hatched 

 in about a week \. the larvae are symmetrical and 



