GENERAL FACTS ABOUT SEA FISH 9 



pout (Gad7(s), mackerel [Scomber), and pilot-fish {Naucrates), 

 are found in the young stages only of the salmon (Salmo), 

 scad (Caranx), and gar-fish {Belone). Some fishes are, like the 

 chameleon, able to change colour to suit their environment ; and 

 the dory [Zeus) has been observed to behave in this manner 

 when about to seize its prey, at which moment the brown 

 blotches on its sides take a distinctly darker hue. The late 

 Matthias Dunn, whose name will frequently recur in these pages 

 as that of certainly one of the most remarkable observers of fish 

 life whom this country can claim, once showed the writer some 

 little turbot {Rhombus) that had been taken half an hour before 

 from the milky clay water off Pentewan, near Mevagissey. 

 The fish were absolutely white and opaque. Transferred to 

 a metal bucket, however, they soon took a dark shade and a 

 semi-transparency. The wrasses (Labrus) are also known to 

 adapt their colour to the background, taking hues suitable to 

 the red or green weed, as the case may be, and they still 

 further accommodate their appearance to the sides of their 

 tank.* This phase of colour-protection is peculiarly associated 

 with flat-fishes lying on the ground for long periods, either 

 resting or waiting for their food, and this aspect of their life is 

 well illustrated by an admirable coloured plate in Cunningham's 

 treatise on the common sole. 



Opinions sometimes differ on the question of what exactly 

 constitutes colour-protection. For instance, in describing an 

 abnormally coloured thornback skate (Raia), which he re- 

 garded as a case of partial albinism. Professor Traquair f 

 suggested that the colouring of the specimen in question 

 could not, in his opinion, protect the skate when lying on 

 any known kind of sea-bed. That specimen was trawled off 

 the Isle of May, with the nature of which ground the writer 

 can claim no acquaintance, but he knows several patches of 



* An interesting account of this behaviour in Labms maculaius may be 

 read in Xhitjourn. Mar. Biolog. Assoc, 1898, p. 193. 



t See Annals of Scottish Natural History, January, 1893. 



