I play a piece by William Byrd on the Keyboard called "Callino Casturame". I tried to figure out what that could mean with my imperfect knowledge of Latin and failed. I asked some people who were more adept at Latin and they were puzzled. Recently a girl from Ireland told me it was a corruption of a Gaelic phrase meaning "I am a (poor) girl by the river" and that it is the oldest written Irish song known.

Does anyone know the phrase? and, in fact anything else about the song.

I know I was a fool for not writing it down, so you don't have to tell me!

Murray