The "Dance in America" TV series brings us to the fringe of contemporary activity in the field tonight with its hour-long program on Pilobolus, the offbeat troupe which recently played a week's engagement at Washington's National Theater.

As the most extensive and elaborately produced survey of American dance ever undertaken for television, the PBS series - nearing the end of its second season - is gradually amassing a priceless archive of choreographic art as it exists today. At the same time, by the nature of the medium, the series is probably introducing more people at one clip to the gratifications of dance than all the live tours of the past decade.

As a furtherance of these goals, the choice of Pilobolus is both logical and odd. It's odd because Pilobolus is so distant, not only from the mainstream but even today's avant-garde, that it is in no way "representative" of today's dance. Nevertheless, the choice is a logical one because no other troupe so concretely tests the limits of dance art. Watching Pilobolus inevitably challenges one's preconceptions about what dance is, or can, or should be. For this reason alone, a program on Pilobolus is bound to be instructive, in the widest possible sense.

For all the automatic advantages of such a program, there is some loss as well as gain. Complete and partial excerpts from the Pilobolus repertoire are shown, with voice-over commentary, and they make a striking effect even on the small screen. But much of the troupe's strong sense of physicality, as well as its dramatic use of light and space, is diluted by the translation to video.

Covering up the male nudity in "Untitled," moreover, not only alters the character of the work but gives a misleading idea of the Pilobolus esthetic.

The "Dance in America" segment airs locally at 9 p.m. on Channel 26. It is followed by an hour-long dance special which displays the dregs of "modernity" abroad - a version of Stravinsky's "Firebird" score choreographed by Eske Holm for himself and other dancers of the Royal Danish Ballet. The original fairy tale is turned into a soft-core orgy, with movement that looks as if it were designed by Russ Meyer. Stravinsky's music is just used as a kind of sexy sound-track, and the choreography is ludicrous.