FISHES, 551 
projecting, and the iris is gold-coloured. When the animal is 
uritated, 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. 36:.—The Hammerhead (Zygzena 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 RAinobatide, contains the genus Pristzs antiquorum, 
the Saw-fish, which is easily distinguished from all other known 
