Although the animated stone-age sitcom The Flintstones was inevitably showing signs of fatigue as the series entered its sixth and final season, there were still enough highlights and innovations to keep fans happy -- and even to attract a few new devotees. The season opener, "No Biz Like Show Biz," finds infants Pebbles Flintstone and Bamm Bamm Rubble suddenly and inexplicably developing the ability to sing! Naturally, this attracts the attention of a big-time music promoter named Eppy Brianstone -- his name of course a takeoff on The Beatles' Brian Epstein. For the record, the babies' big song hit is that old standard "Open Up Your Heart and Let the Sun Shine In," by Stuart Hambles. Nor is this the sixth season's only musical highlight. The episode "The Masquerade Party" features another English rock group called the Way Outs, performing a medley of their hit, titled -- what else? -- "Way Outs.".And a genuine musical aggregation, the Beau Brummels (aka "The Beau Brummelstones"), perform "Laugh, Laugh" on the episode "Shinrock a Go Go," which also features the voice of Jimmy O'Neill (aka "Jimmy O'Neillstone"), who was then host of the live-action variety series Shindig. New to the series this season is The Great Gazoo, an imperious-pint sized green space alien who has been exiled to earth, and who condescendingly grants all sorts of wishes to "dum-dums" Fred Flintstone and Barney Rubble. Introduced in the episode appropriately titled "The Great Gazoo," the character's voice is supplied by Harvey Korman. Other celebrity voices heard durng Season 6 are those of Bewitched stars Elizabeth Montgomery and Dick York in "Samantha," and Tony Curtis in "The Return of Stony Curtis." The 166th and final episode of The Flintstones is "The Story of Rocky's Raiders," clearly inspired by the then-popular "Snoopy vs. The Red Baron" continuity in the Peanuts comic strip; on this occasion, Fred's venerable grandfather recalls his exploits as an ace pilot during Stone World War One.