Mezzo-Soprano arias for university audition?

Well Amarilli (Caccini) is a favorite. There are lots of versions to hear (some superb - some truly awful), you can vary the phrasing and the ornamentation to suit. Bartoli is pretty good for a girl (especially the recorded version, on you tube she is a bit over dramatic) and personally I like Gigli for a guy. Good Luck.