Sentence:  But their depictions of Perseus are remarkably different and demonstrate the ambiguity of <WSD>Medusa</WSD> that was seeping into Victorian iconography. In later, Roman versions of the myth, for example Ovid's "Metamorphoses", Perseus slays the sea monster with his sword instead of using <WSD>Medusa</WSD>'s head to petrify the monster. 
Meaning of the word marked with <WSD> tags:  The only mortal of the three gorgon sisters. She is killed by Perseus. The other two sisters were Euryale and Stheno.