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Courtesy United States Bureau of Fisheries 

 The cow shark {He.Tatichiis (jriseus) is a primitive type of shark, peculiar in possessing six gill slits; most 



modern sharks have but five. Its single dorsal fin is also a distinfiuishint; feature. 

 six feet but is rare on Unitwl Stales coasts 



It attains a length of I went y- 



Courtesy United Stales Bureau of Fisheries 



Basking or bone shark (C.etorhinus nuij-innts). A harmless, sluggish, gigantic shark (nearly forty feet 



long) at home in the Arctic seas but sometimes straying south. Has been described as the fish that swallowed 



Jonah, but, in spite of its huge size and wide mouth, its minute teeth and large gill openings show that it feeds 



on very small marine creatures 



Courtesy United States National Museum 



The smallest shark known (Squaliolus laticaudus), adult female, represented natural size. It is a deep-sea form 

 represented at present by a single pair taken in Philippine waters, at a depth of one hundred and seventy fathoms. 

 The deep-sea sharks are mostly small and dark colored but in structure do not differ markedly from other species 



351 



