Perseus & Medusa

I keep finding all these extremely short myths in this book. This one was barely a page long, whereas the other versions of it I'd read took five hours to read. I wonder if there's any original myth, and all the others are copies of it?

Anywho, Perseus' grandaddy had heard that his daughter's son would be his downfall, so he looked them both in a trunk and set them in the sea (how he managed that is beyond me. Didn't the mother say, "Hey Daddy, why are you locking me up in a trunk? Are we going on a trip? Fun!"), and a fisherman found them. He sent them to his king, Polydectes, who befriended them.

When Perseus was older, Polydectes sent him to kill Medusa, a once-beautiful maiden who had bragged to Minerva that she was prettier than her and in return got a head full of snakes and became so ugly that anyone who looked at her was turned to stone. Apparently, she became horribly cruel, although how anyone knows that is beyond me. Maybe she was just looking for a friend, saw a cute little sailor and said hi, yet the sailor was turned to stone and couldn't return the greeting.

Perseus got winged shoes from Mercury, and from Minerva a shield so shiny he could see Medusa's face's reflection on it and killed her. Although since he obviously wasn't using the shield to shied himself, wouldn't it have made more sense just to get a mirror?