The essence of pop music is its ability to evoke sentimental yearnings and wistful memories. San Francisco's Jellyfish is a pop band once removed, scared to admit its true identity. On stage at the 9:30 club Tuesday night, it hid its sentiment behind the accouterments of camp -- bubble machines, platform shoes, blousy shirts, zany hats and caps -- as if to say, "Sure we can pull off perfect four-part Beach Boys harmonies, but we've got postmodern sensibilities with irony to spare, so don't dare think we're being mawkish slobs."

Jellyfish put on quite a show of pop arrangements but the band's skill was overshadowed by its derivativeness. It's impossible not to hear Beatles and Beach Boys, especially, in the band's music, with nods to Supertramp, Cheap Trick, Gilbert O'Sullivan, 10cc, the Hollies, the Monkees, the Raspberries, Crowded House -- heck, just about every pop purveyor of above-average intelligence in the past 25 years makes it into its musical caldron. While seeming archly calculated, the band's best songs had pleasures that were hard to deny: "I Wanna Stay Home," pegged to a heartbreaking melody and spare arrangement, was best, while the bubbling "Baby's Coming Back" had the sold-out club shaking.

Lead singer and stand-up drummer extraordinaire Andy Sturmer has a strikingly clear voice, as long as he's not losing it, as he finally did after Badfinger's "No Matter What." The rest of the band can sing almost as well, and the harmony arrangements are setting new live standards despite the frequent bouts of sugar shock the band induces.