Conquest of the Planet of the Apes. The fourth of the series of simian-centered fantasies. The time is 1991, and apes have become the new oppressed of the earth (though the humans shown don't seem much better off). Even the serial aspect is fun, though its also getting drawn out, Paul Dehn again has written a clever script, while J. Lee Thompson, who has become a bona fide yard-goods man, directs mechanically. Starts Wednesday at the SAXON.

Wrath of God. Seemed much gutsier than the Last 18 minutes of Duck, You Sucker, which has received far more acclaim. Its full of cliches, but the filmmakers are cynically conscious of them. Robert Mitchum is his typical boozing self, Ken Hutchinson is a fine hotheaded Irishman (where has he been hiding all these years?) Who are resist any Western set in Mexico and dealing with disaffected bandits and revolutionaries? Last day at the SAXON.

Boudu Saved from Drowning, A charming comedy from 1935 about a shaggydog man who disrupts the life of intert bourgeoisie is billed with a Renoir bore and Renoir dud. Picnic on the Grass and A Day in the Country, BRATTLE THEATER. Boudu: 6, 9:35 Picnic: 7:30 Day: 8:55

City Lights, another Chaplin classic (the one with the fight scene). Also, The Go-Between, Losey-Printer decadence again but this time there's a story and some good acting. HARVARD SQUARE THEATER. City: 3, 6:25, 9:55, Go-Between: 1, 4:25, 7:55

Fiddler on the Roof. The musical-comedy for all its shmaltz, was great and the film is a faithful transcription. Norman Jewison directs competently, Oswal Morris's photography is breathing, and Topol's Tevy--virile and touching. CHERII THEATER. 2 and 8 p.m.

The French Connection. Leave your nerve endings at home, along with your emotions, if you plan to see this one. Brutally manipulative and infuriatingly unenlightening about the cops, junkies and underworld kingpins it deals with. SAVOY II THEATER: 10, 12, 2, 4, 6, 8, 10.

The Graduate. Remember Simon and Garfunkel? Remember when loss of sirginity was a fiery crucible for a young man's for woman's) character? Remember when you hoped that Mike Nichols would become a good filmmaker? Neither do I. PARIS CINEMA: 2, 4, 6, 8, 10.

Slaughterhouse Five. Easier to accept than the book, because here Billy Pilgrim is the whole story. Uniformly well-acted, and though it won't shoot your pecker off, it won't leave you untouched. CHERI III THEATER: 1, 2:45, 4:30, 6:15, 8:10, 10:10.

Frenzy. A surprise from the supposedly declining Hitchcock. A virtuosic mix of suspense with apt characterization and subliminal social comment, set, thank God, in London, the director's home town. For once, the audience cheers when the he doesn't kill his enemy. CINEMA 57 II: 10, 12, 2, 4, 6, 8:10, 10:20. Fritz the Cat. An animated send-up of youth, U.S. culture and things in general. Based, for the most part diligently, on R. Crumb's comic books, its pornography is irresistable, its funky satire entertaining on a very low level--making this a trap for snobs, ABBEY CINEMA I: 1, 2:30, 4, 5:30, 7, 8:30, 10.

The Great Dictator. Chaplin made this satire on Fascism in 1939, and the politics are painful in their relative gentleness. But forget the occasional awkwardness; the man's heart was in the right place, and so were his incredible talents--particularly in a ballet of world conquest that the Fooey dances with a bouncing globe. With Jack Oakie. THE PLAZA: 7, 9:30.