bonnet head

from The Collaborative International Dictionary of English v.0.48

bonnet head \bonnet head\, bonnethead \bonnethead\n. (Zool.),
   small harmless hammerhead shark ({Sphyrna tiburio}) of the
   southern United States and West Indies, having a spade-shaped
   head; abundant in bays and estuaries.

   Syn: shovelhead, bonnet shark, Sphyrna tiburo.
        [1913 Webster + WordNet 1.5]