Linebacker Ron Rivera caught Texas A&M's Jimmie Hawkins in the end zone with 57 seconds to play last night to give California a 19-17 victory in College Station, Tex.

The safety came only seconds after California had apparently won on a field goal. But the Aggies roughed the kicker and Cal Coach Joe Kapp elected to give up the points and try for a touchdown.

On the next play, quarterback Gale Gilbert fumbled and A&M's Mike Ashley recovered at the A&M four. Seconds later, Rivera tackled Hawkins in the end zone.

The Aggies' "12th-man" experiment on the opening kickoff failed. Alan Smith, the regular kicker, tried an onside kick but one of the A & M irregulars touched the ball before it went 10 yards; Cal took over on the Aggies' 46 and quickly scored. Cal led at the half, 17-0.

"The onsides kick was disappointing but there was nothing we could do," Ike Liles, a senior on the 12th-man squad, said.

But Liles atoned in the third period when he downed Cal's kick returner, Dwight Garner, on the Bears' 17. The crowd of 51,971 roared and the Aggies' regulars went into a frenzy on the sideline.

The 12th man unit is composed of volunteers from the student body.