then the lion sprang and the unicorn plunged , and the glade was filled with gold and silver and red , for the lion was on the unicorn 's back , claws gashing deeply into its flanks , mouth at its neck , and the unicorn was wailing and bucking and throwing itself onto its back in an effort to dislodge the great cat , flailing uselessly with its hooves and its horn in an effort to reach its tormentor .