Over the years, Bob Weir has accumulated more than a touch of gray. The icon’s beard and bushy mustache are peppered with shiny silver and white, and waves of gray flow through his thick hair. Watching him onstage, the guitarist and singer at first looks like a hoary vestige of his former self. But, in his eyes and in his voice, Weir still manifests the spirit of a strange and beautiful counterculture that he helped create more than four decades ago.

Although he was the youngest founding member of the Grateful Dead, Weir has reached the ripe age of 60, making him the veteran bandleader of RatDog. Formed in the mid-1990s, around the time of Jerry Garcia’s death, RatDog has been satisfying hippie hangers-on for well over a decade. On Saturday, May 31, the band returned to the Casino Ballroom for a sold-out show on the beach. The crowd was elated and rambunctious even before the music began, and at times during the concert, the roars of approval reached an absolutely deafening pitch.

After a funky opening jam, Weir promptly launched his band into an extended version of “Shakedown Street,” off the Dead’s 1978 album of the same name. The instantly recognizable psychedelic disco quickly put the audience in a fleet-footed, dance-happy mood that would endure until the final curtain call.

RatDog did not confine itself to Dead tunes. The third song was “Maggie’s Farm,” the first of two Dylan covers of the night, which would be matched by a pair of Beatles covers. “Maggie’s Farm” dragged a little bit, and the next song seemed a little too lethargic to uphold the kinetic atmosphere. But Weir later bounced back with an enlivening version of Dylan’s “Hard Rain,” which seemed to teleport everyone back into the musical revolution of the 1960s.

Other highlights included the Beatles’ seminal dip into psychedelia, “Tomorrow Never Knows,” and a long and indulgent cover of “Dear Prudence.” The Dead’s “Eyes of the World” was an obvious crowd pleaser, as was an exultant performance of “One More Saturday Night.” Wearing a sleeveless shirt and sidling up to the microphone with the confidence of an experienced rocker, Weir gave the crowd exactly what it was looking for: an evening that reawakened their dormant hippie spirits and projected them directly into the hazy reaches of their Deadhead memories.

It was amusing to watch the audience, which was composed of equal parts neo-hippie youngsters and middle-aged baby boomers. Fans who fell into the latter category were especially energetic. The once Deadheads-turned-“Boneheads” (that’s the preferred term for RatDog followers) may have grown bald and portly, but they still proudly donned their old tie-dye shirts and spun and wriggled around the crammed dance floor, bouncing and pirouetting about like psychedelic My Little Ponies. 

At times, Weir seemed to put a little extra push into his vocals, and it warmed the crowd members’ hearts to hear his undiminished voice. He settled for a secondary role on guitar, however, letting Mark Karan deftly mimic Garcia on a seemingly endless stream of solos. Saxophonist Kenny Brooks also dealt the audience some extra thrills, while drummer Jay Lane, keyboardist Jeff Chimenti and bassist Robin Sylvester filled their roles expertly.

By the time the encore was over and the band congregated for a final bow, the crowd seemed thoroughly sated. Some fans mustered enough energy to cheer halfheartedly when the drummer made a marijuana smoking gesture before leaving the stage, but most had already exhausted their energy, leaving all those musty sentiments of peace and love to be swept up from the Ballroom floor.