Crumbs! That's about all the Metropolitan Opera Ballet gets to dance, but at least they are crumbs of different dough. One night it's X-rated orgy in "Samson and Delilah" while the next day it is innocuous kiddies' fare. As its contribution to the Imagination Celebration, the Kennedy Center's current festival of art for children, the Met's moving corps is presenting a double bill of "Peter and the Wolf" and "Babar the Elephant" in several school performances and, yesterday evening, in a single public showing at the Terrace Theater.

"Babar had a whiff of imagination. Norbert Vesak's choreography kept David O. Roberts' elephant, dromedary and monkey costumes as well as Miguel Romero's scenic screens moving as part of a total picture, despite Jean de Brunhoff's choppy narrative. For "Peter," Donald Mahler relied on standard bits of ballet. The young hero performed a few vigorous jumps and partnered the Bird, who balanced and bourreed on the tips of her toes while Duck, Cat Wolf and the grownups were frugal representatives of character dancing and pantomime. It was a threadbare conception compared to Adolph Bolm's version for Ballet Theatre in the 1940s.

Irving Owen, on the piano, played the Prokofiev music for "Peter" and the Poulenc for "Babar." Donald Mahler was host and narrator. Lacking was the immediacy of vibrant live theater.