Who are the "Furies"?

The "Furies" are mythological spirits who pursue criminals and often drive them crazy. Lizabeth described herself as running as if the "Furies" were chasing her on her way to Miss Lottie's yard..... an act of madness.

I was running as if the Furies were after me, as perhaps they were—running silently and furiously until I came to where I had half known I was headed: to Miss Lottie’s yard.