Cornix is a character in Ovid's Metamorphoses.
There, she recounts how she was a princess, the daughter of Coroneus. One day as she was walking by the seashore, Neptune saw her. When attempts to persuade her were unavailing, he attempted rape. She fled, crying out to men and gods, and while no man heard her, "the virgin goddess feels pity for a virgin": Minerva transformed her into a crow. She also cites her resentment that her place as Minerva's servant is being taken over by Nyctimene transformed into the owl, where the transformation was punitive.
John Gower took up the tale for use in his Confessio Amantis, with particular emphasis on her delight in her escape:
With fetheres blake as eny cole
Out of hise armes in a throwe
Sche flih before his yhe a Crowe;
Which was to hire a more delit,
To kepe hire maidenhede whit
Under the wede of fethers blake,
In Perles whyte than forsake
That no lif mai restore ayein.
Source 1: Metamorphoses by Ovid