Now fly; for the other Gorgons will do their utmost to take vengeance for Medusa's death.
This was to bring him the head of Medsa, one of the Gorgons.
Perhaps the reader does not know that the Gorgons are not dead, are ever undying.
The Gorgons are not known to be useful either in the arts or in medicine.
Then Perseus went on and on until at last he came to the Gorgons' lair.