Guillermo Sarabia, a Mexican-born American baritone who sang with both the Metropolitan Opera and the New York City Opera, died of a cerebral hemorrhage Thursday night in Amsterdam, where he lived. He was 49 years old.\r \r Mr. Sarabia`s most recent New York appearance was in April, when he sang the title role in a concert performance of Verdi`s ``Falstaff`` at Carnegie Hall with the Chicago Symphony and Sir Georg Solti. In his review, Donal Henahan of the New York Times wrote: ``Mr. Sarabia proved to be a Falstaff with enough voice and more than enough wit to hold the drama in focus. He was appropriately despicable in his `Honor` monologue, amusingly rueful in `Va, vecchio John` and touching in his tattered dignity in the old scamp`s final speech.``\r \r