Fantasy, the fourth Disney cruise ship, was christened Thursday night in New York City. The 4,000-passenger, 14-deck ship with its distinctive mouse ears logo, was built in Germany. It will sail on sevennight Caribbean cruises beginning March 31 from Port Canaveral, Fla. The ship is a near-twin to the Disney Dream, which was launched a year ago. Motifs from Disney stories and characters turn up throughout the ship, including a French restaurant that was inspired by the movie Ratatouille.