The Folk Arts Program at the National Endowment for the Arts has distributed its second annual National Heritage Fellowships. So far, thirty-one individuals have been singled out tor national recognition as "exemplary master folk artists and artisans," and honored for their "authenticity, excellence and significance within a particular artistic tradition," and for their ''ongoing artistic accomplishment." The art forms of these master folk artists have ranged from duck decoy carving to quilting, from ballad singing to bagpipe playing, from storytelling to Afro-Puerto Rican homha dancing. The artists have come from all sections of the nation as well as Puerto Rico; they speak in Yankee English, Louisiana French Cajun patois and Texas-Mexican Spanish; they are black, brown, red, and white; they hail from big cities and from country farms; some are women, some are men. All of them, however, were over fifty when they received their awards, a fact made the more remarkable when one realizes that their ages were not generally cited in the letters of nomination. But "ageable" they all were- five in their fifties, eight in their sixties, eight in their seventies, seven in their eighties, and a triumphant three, ninety years old or over.