GOOD LUCK with the motivation behind City of Women, Federico Fellini's latest baroque-nightmare-cum-flesh-fantasy. Food for thought and conversation, perhaps, but it yields no neat, coherent conceptual summary--better just to sit back and savor.

Snaporaz (Marcello Mastroianni), conservatively attractive--"fifty but still nifty," he claims humorously--and devoted to the pursuit of the Ideal Woman, chases a lushly likely prospect out of a train and into a deserted forest miles from civilization. Turns out, she is en route to a feminist convention--and thus begins the saga of Snaporaz, a hallucinogenic journey through an amusement park gone wrong.

No ordinary feminist convention, this. The lesbians, sex kittens, Amazons and fashion models here pack the hotel; attired in leather and chains, gauze and spangles, disco Spandex and Southern belle white, they hang from the ceiling and leer out of doorways. Their cigarette smoke makes haze of the atmosphere; their singing and screaming and chanting and ranting produce an unholy, stupefying, din. They are painted like puppets; they contort and disport to uncanny visual effect.

Snaporaz seems good-naturedly inclined to dismiss this manifest lunacy as an extreme example of the illogical, though often charming, behavior of the weaker sex. Soon, however, he is spotted by a woman, and she incites her cronies to violent retaliation against male sexual oppression, embodied in Snaporaz. Through a gymnasium bursting with women lifting weights and practicing testicle kicks he rushes, down into the fiery furnace below.

The furnace in the basement is stoked by a hideous hag, an anti-bella donna, who bundles the hapless Snaporaz onto her motorcycle and roars off with him, ostensibly to the train station. Instead, she attempts to rape him in a greenhouse, chickens squawking between them and stuffed cars reposing on a nearby table. Rescued in the nick of time by the rapist's mother, Snaporaz entrusts himself to his attacker's daughter.

She meets up with her friends down the road, and they cruise all night. Three carloads of drugged, glassy-eyed, wild-haired teenage girls lurch along dirt roads, frenetic music stimulating them like an electric cattle prod into disjointed spasms. Snaporaz eventually flees, panicked, into the pleasure palace of Dr. Xavier Zuberkock, an aging Bacchanalian who calls to mind the incoherent but dynamic Mynheer Peeperkorn of Mann's Magic Mountain.

Zubercock's residence, fashioned after the Roman decadent style, contains all manner of sexual appliances--12-inch vibrators, lamps with tongues, ad infinitum--as well as a gallery chronicling the good doctor's 9,999 conquests. Snaporaz browses, flipping switches and enjoying the recordings of female groans, grunts, and squeals of pleasure, and then joins in the celebration of Zubercock's ten-thousandth performance. A troop of policewomen sporting highheeled boots and skin-tight, wicked uniforms disperses the party prematurely.

Worn out and befuddled, Snaporaz is tucked into bed by two girls in go-go costumes. He hears giggling nearby, and crawls under the bed to investigate. A spin along a velvet-lined roller coaster track treats him to a panorama of his past sexual encounters. At the bottom of the track, in hideous anticipation, wait the women of the convention. They hurl him into a cage and truck him off to his trial. Acquitted of an unknown crime. Snaporaz elects nevertheless to suffer the punishment: revelation of his Ideal Woman.

THE FILM BEGINS innocently enough: man on train lusts after shapely woman with ripe lips and big eyes. Once the feminist convention has burst onto the scene in all its mad-house glory, we know we're not in Kansas anymore. As thorough in his evocation of an Unreal City as both T.S. Eliot and Franz Kafka, Fellini creates an action-painting so surrealistic, so whirling, and so blinding that the ringing of an unseen telephone in several scenes seems an inexplicable and absurd reminder of everyday life.

As usual, Mastroianni plays with just the right combination of irony and seriousness. His good looks and polite detachment make him the sort of man every woman hates to love (but does anyway). The women--all the women--cannot be faulted. The menacing atmosphere that they create is alive and palpable and terrifying. Except when galvanized into specifically hostile action, they should appear happy, involved women's women, each doing her own thing: instead, not mobilized, they pose a terrific implied threat.

So: criticism or celebration of feminism? Both, and neither. Fellini asserts consistently in interviews that he likes and respects women enormously. True, probably, but he indicates with equal vehemence on film that he feels confused, if not actually intimidated, by the opposite sex. His relation with females seems one of fascination rather than understanding.

The women who populate the City of Women certainly intrigue and captivate: they are attentiongetters, every one. What they lack entirely is humanity. As woman in nightmarish fantasy, well and good. As woman in life, they don't exist.