lo8 ^^^^ second. 



side as from the other, the Flat-fish are asymmetrical. On one 

 side, the lower, they are pale coloured, and on the other, the upper, 

 dark and, moreover, both eyes are placed on the dark side. A 

 young Flat-fish lacks these characteristics, being quite symmetric- 

 ally formed and it is exceedingly interesting to follow the gradual 

 migration of the lower eye to the edge of the head and then up 

 on to the upper surface, finally reaching a position close to the 

 other eye. This change in position of the one eye necessitates a 

 twisting of the skull-bones. The use of this modification is ob- 

 vious : since the Flat-fish lies on one side on the sand, it would be 

 useless to have one eye directed downwards towards the ground. 

 — The upper side of the Flat-fish possesses to a high degree the 

 power of matching itself to the colour of the bottom in a most 

 remarkable manner. This protective colouring makes it at times 

 very difficult to distinguish the specimens. The eyes will be 

 the first objects to reveal themselves to the spectator; they can 

 be moved about independently of each other in all directions, 

 raised up or retracted, so that the fish commands a complete 

 view of its surrounding. It catches its prey, consisting of small 

 fish and shrimps, by darting upwards and forwards with light- 

 ning-like rapidity. It swims with great skill, by wave-like motion 

 of the body, the dark side being uppermost. A few strokes of the 

 loose flaps of skin which encircle the body suffice to throw up 

 sand enough to conceal the animal again, and then it will remain 

 for hours awaiting its next prey. 



Economically the Flat-fishes are very important, as their flesh 

 is very delicate and keeps well, so that it can be transported to 

 considerable distances. Some of them attain a large size. England, 

 Germany, France, Holland and Denmark consume enormous num- 

 bers of Flat-fish and in the Italian markets, too, they are greatly 

 prized. They are caught with the Trawl-net, and also with the 

 line. The chief kinds of Flat-fishes are the Flounder, the Turbot 

 and Halibut, the Sole and Plaice. Only the smaller species can 

 be kept in Aquarium; generally the Turbot, Rhombus maximus 

 (fig. 150) and the Sole, Solea vulgaris (fig. 151). 



Allied in habits to the fishes just described are those which 

 have adopted the crevices of the rocks as their home and there 

 lie in ambush for their prey. Foremost amongst these is the 

 Sea-scorpion or Sea devil, Scorpaena (fig. 43), a heavily shaped 

 fish with a broad head and mouth, large spiny fins, and curious 

 appendages on its skin in form of lappets, horns or ribands. They 

 hide themselves in the crevices of the rocks, and can mimic the 

 colouring so wonderfully that visitors will not be able at first to 

 distinguish them (tank Nr. 6). Some, in the semi-darkness of 

 the water, bear a most striking resemblance to a rock covered 

 with sea-weeds, so that they easily escape the notice of their 

 enemies and also of their prey. — Such similarity of the appearance 



