Tanks No. 24 and 25. 
75 
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 numbers of Flat-Fish. London 
imports from Holland alone about ^100,000 worth of Turbot annually, 
but this is only a quarter of the amount actually consumed in the metro¬ 
polis ; in the Italian markets, too, they are greatly prized. They are 
caught with the trawl-net, and also with the line. The chief forms of 
Flat Fishes are the Flounder, the Turbot and Halibut, the Sole and 
Plaice. Only the smaller species can be kept in the Aquarium, generally 
the Turbot, Rhombus maximus (Fig. 127), and the Sole, Solea vulgaris 
(Fig. 128). 
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, 
Fig. 129. Scorpaena porcus, Y 2 nat. size. Tank 25. 
Scorpaena (Fig. 129), 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 at first 
not be able to distinguish them (tank No. 25). 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. The same is the case with the crabs, in this 
same tank (see above p. 43); and in fact this protective colouring is 
found in many animals. Thus the inhabitants of the deserts are usually of a 
sandy colour. The Polar regions and the alpine heights are inhabited 
by white animals, some of which, like the ptarmigan, can even change 
their colouring according to the season of the year. The jelly-fish and 
the other pelagic forms protect themselves from their enemies by perfect 
transparency. Some insects and their larvae mimic the plants, or portions 
of the plant, on which they live and feed. Others, again, mimic animals 
