a shark of the genus sphyrna or zygaena, having the eyes set on projections from the sides of the head, which gives it a hammer shape. the sphyrna zygaena is found in the north atlantic. called also hammer fish, and balance fish.-a fresh-water fish; the stone-roller.-an african fruit bat (hypsignathus monstrosus); -- so called from its large blunt nozzle.