BRITISH FRESH-WATER FISHES 
Flounder.—Pleuronectes flesus (Fig. 64). This, the 
last species which it is desirable to include in our list of 
fresh-water fishes, migrates considerable distances up- 
river, and although there are many other species of 
marine fishes which frequent brackish and even fresh 
water, there is not much amiss with the selection that has 
been made in this volume, and the Flounder is certainly 
entitled to inclusion in preference to several others. It 
is, as is well known, one of the flat-fishes, having an 
ovate body, with an array of fins extending at least three- 
fourths of the whole. The body is covered with small 
scales, and along the inside length of the dorsal and 
ventral fins there is a row of spinous tubercles, as also a 
little group at the head end of the lateral line. The 
general colour is greyish-olive, but there is considerable 
variation, and one writer says “it varies from nearly 
yellow to almost black.” In some specimens there are 
orange spots, as in the Flounder’s nearest relative, the 
Plaice Left-sided, as well as right-sided, examples are 
frequently forthcoming, as also specimens coloured alike 
on both sides. It resorts to shallow water close inshore 
and delights in a sandy bottom. Although of sluggish 
habits, it regularly ascends a number of our rivers, and 
when swimming, its movements are most fascinating to 
watch. When I was on Loch Lomond in the Autumn of 
1922 a Flounder was captured in the famous Loch, 
the first that had been known to appear there for over 
twenty years. ‘The food consists of crustaceans, molluscs, 
worms, and small fishes. ‘The spawning time is of ex- 
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