Jockey Mark Guidry missed his Sunday mounts at Arlington International Racecourse as the result of a spill at the Chicago-area track on Saturday. Guidry was treated and released from Northwest Community Hospital in Arlington Heights, Ill., after he was thrown to the track when his mount, Lex a Million, broke down at the half-mile pole during the seventh race on Saturday. According to his agent Dennis Cooper, all tests came back negative."He's still pretty sore," Cooper said Sunday afternoon. "He's off all his mounts today and I didn't put him on anything Wednesday. As far as Thursday goes, we'll play it by ear. I'll talk to Mark tomorrow morning and see how he feels."Guidry, the leading rider on the current Arlington International meet with 119 victories, was scheduled to ride Bella Chiarra in the Gardenia Handicap (gr. III) at Ellis Park on Saturday but picked up mounts at Arlington International when she was scratched from the race.