San Francisco in the mid '60's saw the metamorphosis of folk into acid rock, with groups such as the Grateful Dead, Quicksilver, Messenger Service, and Big Brother and the Holding Company. Those folk roots were soon obscurred by the electric guitar's psychedelic light shows and drug-induced improvisation.

Yet the similarites remained. Both were allegoricar: Folk used narratives to illustrate feelings; acid rock used abstract images.

Rober Hunter, chief lyricist for the Grateful Dead and chronicler of the golden age of love, has had his own kind of metamorphosis -- from behind the scenes to on-stage, from writer to singer/songwriter. It's a big step from professing to performing, but last night at the Cellar Door he proved that he's equal to the task and and that his music is as well suited to a folk as to a rock interpretation.

In a set drawn for the most part from Dead material, Hunter was as folksy as corncob pipes and fiddles. He picked and tuned and chatted and played harmonica and acoustic guitar at the same time in, good folk tradition. His deep baritone was melow yet strong.

His metamorphosis was all the more remarkable in light of the company his songs have kept for the last 10 years. Depending on your taste for folk and rock you might call him a moth or a butterfly.