According to Pindar, a goddess attempted to imitate the sound of two of these beings crying by inventing the aulos flute. Two drops of blood from these beings were gifted to either Erichthonius or Asclepius for use as a panacea. The death of one of these beings spilled blood that mixed with sand to create the viper that killed the (10[2]-5[1])Argonaut Mopsus (10[1])and created a warrior named for being born with a golden sword. (-5[1])Ceto mothered two immortal examples of these beings named Stheno (10[2])and (10[1])Euryale. (10[2])The head (10[1])of the only mortal one of these sisters is placed on the aegis (10[1])by Athena after Chrysaor and Pegasus are born from her beheading by Perseus. For 10 points, what snake-haired sisters from Greek myth include Medusa? ■END■ (10[2])