There was also useful batting practice for JP Duminy (53), Morne Morkel (38), Robin Petersen (33 not out) and AB de Villiers (23) on a day dominated by news of Mark Boucher’s retirement from international cricket.
Somerset had added 50 for one to their first innings score of 312 for eight declared.
From 96 for two at the start, the tourists progressed sedately to 134 before de Villers, who had replaced Kallis, was bowled off a thin inside edge by medium-pacer Peter Trego for 23.
When Somerset batted again Arul Suppiah bagged a pair, pinned leg before by Philander, whose new ball partnership with Steyn again looked impressive. Alex Barrow was unbeaten on 31 when the teams shook hands at just before 5pm.