THE SHORES OF BRITAIN. 83 



change in their depth of water, have the ventral fins 

 placed far back on the belly, as the Herring and the 

 Salmon ; while those which feed at the bottom in deep 

 water, but vet have considerable power of swimming, 

 such as the Cod, require the ventruls to be situated 

 near the head, sometimes even in advance of the pec- 

 torals, in order to act with rapidity and effect upon 

 the fore part of the body, which is usually heavy in 

 such fishes. The Flat-fishes and Skates, in which the 

 ventrals are little developed, and the Eels, in which 

 they are wanting, rarely quit the ground, but grovel 

 on the mud in shallow water. Many fishes have cer- 

 tain spines of the fins developed into stiff and for- 

 midable weapons, and others have equally effective 

 armour placed upon the gill- covers, the sides of the 

 body or the tail. With these, which are usuaily 

 jointed, and which the fish has the power of erecting 

 stiffly, and of directing with considerable precision, it 

 sometimes inflicts severe wounds on the incautious 

 fisherman, as well as on its opponent, in the battles 

 with its own kind, which often occur. The little 

 Stickleback (Gasterosteus), which abounds all round 

 the coast, as well as in our fresh waters, is armed 

 with sharp spines on the back and sides, which it 

 wields like a perfect tyrant. " When a few are first 

 turned into a tub of water, they swim about in a 

 shoal, apparently exploring their new habitation. 

 Suddenly one will take possession of a particular 

 corner of the tub, or, as it will sometimes happen, of 

 the bottom, and will instantly commence an attack 

 upon his companions ; and if any one of them ven- 

 tures to oppose his sway, a regular and most furious 



