The Hammer-headed Shark. 421 



fearless of mankind. They follow vessels with great 

 eagerness, seizing with avidity everything eatable that 

 is thrown overboard ; and have sometimes been known 

 to throw themselves on fishermen, and on persons bath- 

 ing in the sea. As, however, they are much smaller 

 and weaker than most of the other Sharks, they do not 

 always attack their enemies by open force, but generally 

 have recourse to stratagem. They, consequently, con- 

 ceal themselves in the mud, and lie in ambush, like the 

 ray or skate-fish, (also one of the cartilaginous fishes,) 

 until they have an opportunity of successfully attacking 

 their prey. On the coasts of Scarborough, where had- 

 docks, cod, and Dog-fish are in great abundance, the 

 fishermen universally believe that the Dog-fish make a 

 line or semicircle to encompass a shoalof haddocks and 

 cod, confining them within certain limits near the shore, 

 and eating them as occasion requires : they are there- 

 fore considered very destructive to this fishery. The 

 flesh of the Dog-fish is hard and disagreeable ; its skin, 

 when dried, is made into the well-known shagreen, and 

 from the liver a considerable quantity of oil may be 

 extracted. Shagreen is also made from the skin of other 

 cartilaginous fishes. 



THE HAMMEK-HEADED SHARK, (Zygoma malleus,) 



Is a very curious kind, having a transverse head like 

 that of a hammer, with an eye at each extremity ; and the 

 Fox-Shark, or Thresher (Carcharias vnlpes), is remarkable 

 for the enormous length of the upper lobe of its tail, 

 with which it is able to strike with tremendous force. 

 This fish is one of the great enemies of the whale. 



