JUPITER'S THIGH -- At the Janus.

Cherchez la "Dear Inspector." It won't be easy in "Jupiter's Thigh," a disappointing sequel to that farcical French romp that delighted subtitled film fanciers a few years back.

From the first, it's a bust. Annie Girardot, as that saucy, super gen darme Lise Tanquerelle, breaks up a passel of drug dealers before the open ing credits, but fades into the scenery shortly after she and new husband An toine Lemercier, played by Philippe Noiret, begin their honeymoon in Greece. Director Philippe de Broca can't resist showing off the snazzy set ting and soon abandons his actors for long shots of the landscape, occasion ally closing in on a ruined Athenian profile.

Finally his travelogue is interrupted when the newlyweds drop a really old rock on the head of dedicate d archae ologist Charles-Hu bert Pochet, who later will discover that wonder of the ancient world, the "Buttocks of Aphro dite," about which the plot will be wrapped like a pair of baggy Calvins. Pochet, portrayed by Francis Perrin, also brings to the plot film spouse Agnes Pochet, a basic blond Bardot clone and owner of a gross of white bikini underpants.

Madame Pochet, played by Cather ine Alric, first meets the Lemerciers in one of her favorite white undergar ments after her bumbling spouse has invited the derring duo over for din ner. When C-H finds cat munchies in his favorite fifth-century dish, the young lovers quarrel. But, ooh la la, be fore the Lemerciers can duck out that door, moans from the chambre a couche indicate that making up isn't hard to do.

It seems the goddess of love appreci ated the tribute, for on the morning after, Aphrodite's buttocks are uncov ered by the bumbling Monsieur Po chet, whose leg is broken when Mad ame Pochet's extracurricular love in terest, Aristotle, lets slip the marble derriere. Later, Madame Pochet per suades her lover to steal the buttocks and have them appraised. If they're worth enough, she plans to sell them and buy her husband a bulldozer.

Perhaps, despite all that moaning, the earth did not move for Monsieur Pochet. As Agnes, Catherine Alric is woodenly seductive with or without her lingerie. Understandably the in spector smiles indulgently when her new hubbie snuggles up to this not- quite-ripe tomato in later scenes.

Overall there's too much Alric and too little Girardot. What's the point? That's like "Superman II" without Su perman. Bring on Girardot as the in spector, a Jeanne Moreau kind of looker with great legs and a good right jab. She's the kind of heroine little French girls can look up to. Big Amer ican girls, too.

Philippe Noiret is also wasted in film number two. The film relationship de veloped between him and Girardot in "Dear Inspector" was transformed into a three-way back rub in ''Jupiter's Thigh."

This sequel has all the ingredients that make for a good French farce -- love, lingerie, sex and chase scenes. Alas, the measurements are off or something is lost in translation.