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head anatomy but saw nothing that even suggested its purpose. 

 Whatever its function, the creature's bow was certainly no 

 hindrance, for it was one of the most active sharks I have ever 

 seen. The nurse sharks are the Southerners of their family; 

 nothing except fright ever makes them move beyond a cer- 

 tain leisurely pace. The hammerheads, by comparison, are 

 metropolitan New Yorkers; they are bursting with impatient 

 energy, restlessly scurrying here and there, working like the 

 very devil to make a living, rushing through hf e as though their 

 very existence depended on speed. Already excited by its easy 

 meal of mollusks, the hammerhead was circling and swooping 

 at a dizzy rate. Its appetite must have been whetted, for it be- 

 gan pursuing several small wrasse which, attracted by the scent 

 of the mollusks, had injudiciously left their clump of isolated 

 coral faintly visible in the distance to seek food. One of the 

 wrasse escaped by diving headlong into a hole in the bottom 

 which had been constructed by some sort of animal, for there 

 was a considerable circle of piled up silt around the entrance. 

 The other was not so fortunate. It made the mistake of dash- 

 ing in a straight line for its coral home. The shark then gave 

 one of the most masterly exhibitions of water acrobatics I have 

 ever seen in all my hours of diving. It lunged after the wrasse 

 which was vibrating its tail so rapidly that it could scarcely be 

 seen. The midget was putting its last ounce of energy in its 

 dash for life. But it was no equal for the hammerhead. The 

 big fish swooped over its tiny prey, hovered for a split second 

 and then dived. The wrasse, sensing the tragedy over its head, 

 suddenly halted and with a violent twist of its body reversed 

 its direction. But too late. The hammerhead did a magnificent 

 Immelmann turn, curving backward in its own length, and 

 then coming down again in a rushing dive gave a half turn, 

 opened its mouth and snapped it shut on the wrasse. Without 

 a stop the shark did another twist before it hit the bottom, 



