FISHES. 



551 



is 



projecting, and the iris is gold-coloured. When the animal 

 irritated, the colours of the iris are said to become like flame. 



Beneath the head and near to the junction of the trunk is the 

 mouth, which is semicircular, and furnished on each jaw with three or 

 four rows of large teeth, pointed and barbed on two sides. 



The most common species in our seas is long and slender in the 

 body, which is grey, the head blackish. It usually attains the length 



Fig. 363. The Hammerhead (Zygsena malleus). 



of eleven or twelve feet, weighing occasionally nearly 500 Ibs. Its 

 boldness and voracity, and craving for blood, are even more re- 

 markable than its size. If the hammerhead has not the strength of 

 the shark, it surpasses it in fury ; few fishes are better known to 

 sailors, in consequence of its peculiarly-shaped head. Its voracity 

 often brings it round ships, even in roadsteads and near the coast. 

 Its visits impress themselves on the memory of the sailor, and he 

 loves to relate his hairbreadth escapes from the meeting. 



The family Rhinobatidce, contains the genus Pristis antiquorum^ 

 the Saw-fish,, which is easily distinguished from all other knowi> 



