I need a ROMAN myth about the constellation pegasus ASAP?

I need a ROMAN only myth right away about the entire constellation not about the stars in it! I already have how it was born from Medusa's neck. Due in the morning!I need a ROMAN myth about the constellation pegasus ASAP?She was called Medusa , or her Latin name Rondanini. The mythological stories seem to be the same. However, the following link does quote some Roman sources...