350 VERTEBRATES. 



placed at each extremity of the head, must of course possess a 

 very extended power of vision. 



The Thresher, a fish which has a curious habit of spring- 

 ing out of the water and inflicting a violent blow with its tail on 

 any object that annoys it, belongs to the Shark tribe. 



The Sawfish is found in the greatest perfection in the 

 tropical seas, although it also inhabits the Mediterranean. The 

 weapon from which the fiou derives its name, is a flat, long pro- 

 longation of the head, on each edge of which are set hard tooth- 

 like projections, curiously inserted into the bone. 



This fish has been known to employ its saw in the attack 

 of the whale, burying the apparently inappropriate weapon to the 

 very root in the body of the whale; nor are instances wanting 

 where the saw has been found firmly imbedded in the hull of a ship. 

 The strength of the Sawfish is very great. Captain Wilson 

 gives an account of the capture of a Sawfish, measuring twenty- 

 two feet in length, and weighing nearly five tons. After the fish 

 had been entangled in a net for several hours, making violent 

 efibrts to escape, Captain Wilson got a rope firmly fixed round its 

 saw, and set thirty men to haul at the rope. The whole thirty 

 could not move it one inch, nor was it until one hundred men had 

 been pulling at the rope for nearly the whole of the day, that they 

 succeeded in dragging it on shore. Even then it made such vio- 

 lent strokes with its saw, that they were forced to fasten strong 

 guy ropes to prevent it from cutting them to pieces. It was finally 

 disabled by a Spaniard, who cut through the joint of the tail. 



The Torpedo afibrds a se- 

 cond instance of the electric power 

 residing in a fish. The organs that 

 produce the electric shock are 

 shown externally by two elevations 

 extending from the eyes about 

 half down the body. 

 Although it has once or twice been caught on our coasts, it 

 is usually found in the Mediterranean, where its powers are well 

 known, and held in some awe. The shock that the Torpedo gives, 

 of course, varies according to the size of the fish and its state of 



