It may be called Alvin Ailey, but its dances come from many sources

Among dance companies named after their artistic directors, the Alvin Ailey American Dance Theater is unusual in that its repertory is becoming increasingly eclectic. The Ailey company's current season at the New York City Center (through May 23) is the perfect example of this trend. The two new works aren't by Ailey; they're not even by company dancers turned fledgling dancemakers.

That the Ailey troupe chooses to look outside its own boundaries to find new material might be interpreted as a sad reflection on Ailey's powers of creativity. The happy fact, however, is that outside choreographers are bringing new styles and points of view into a company whose profile has often been flattened by a preponderance of Ailey and Aileyesque works.

A strong new shape comes from Elise Monte -- who, when not making her own dances, performs those of Martha Graham as a soloist with the Graham troupe. Part of Monte's new shape is actually a new voice, reflected in the music she favors. Whereas much of the Ailey repertory is set to jazz, blues, and contemporary composers like Bartok, Monte likes the sound of the avant-garde musicians whom I would call spellbinders.

Much of the power of Monte's new ''Pigs and Fishes'' comes from the repetitive undulations and smooth harmonies of Glen Branca's score. Similar in effect to Ravel's ''Bolero,'' Branca's music and Monte's dance accumulate force through narrowness, rather than variety, of scope. The idea is to do the same thing over and over -- almost. Everything rides on the ''almost.'' In Monte's hands, the principle works. ''Pigs and Fishes'' rides, and it moves somewhere.

Its basic motifs are spirals and ''S'' shapes. Monte's ability to work only with those motifs, and yet fashion them into movement through group patterns and counterpoint, is impressive. Yet what makes ''Pigs and Fishes'' theatrically viable isn't so much Monte's craft, and craftiness, as the inherent sensuousness of the motifs themselves. ''Pigs and Fishes'' works on the premise that if one ripe peach is luscious, 10 ripe peaches are a hundred times as luscious.

Some people might blanch at the mere thought of consuming so much lusciousness. Monte brings us to the brink of satiation, but doesn't let us go beyond. For one thing, the patterns and dancers' inflections are sharp and clear. Also, the all-women cast moves through their snakey spirals with Amazonian weight. They could almost be peasant farmers tilling the soil -- or if you want to be fanciful -- tribal women enacting a rite of spring.

''Pigs and Fishes'' encourages one to go the fanciful route. Starting off as a formal exercise in repetition, it easily becomes a metaphor of life process.

''Pigs and Fishes'' presents the Ailey women in a new guise. Rather than masquerade as sleek models, the women in Monte's dance may stress their sensual earthiness. The new note in Rodney Griffin's new ''Sonnets'' is its literary-mindedness. Set to music by John Dowland and prefaced with a quote from Shakespeare, ''Sonnets'' is about a poet in mid-life crisis. He has outgrown youth, represented by a character called the Friend, and he cannot quite reach his highest level of achievement, represented by the Dark Lady.

At least this is one viewer's interpretation of ''Sonnets.'' Judging from titters in the audience, others might have different notions. This confusion of response measures accurately the dance's fuzziness. But simply in terms of its artistic substance, ''Sonnets'' is a refreshing addition to the Ailey repertory.