Scarlets ended a four-match RaboDirect PRO12 losing streak to gain a 33-17 bonus-point victory as centre Adam Warren scored two tries against Edinburgh on his first league start.
Warren, who stepped in when skipper Gareth Maule was injured in the warm-up, went over for a try in each half. There were also tries for Richie Pugh and Rhys Thomas.
A virtuoso kicking display from fly-half Duncan Weir saw Glasgow break their winning duck at home this term with a 24-19 win over Newport Gwent Dragons.
Weir's eight successful penalty attempts accounted for all his side's points, and in the process he equalled the RaboDirect Pro12 record for the most penalty goals in one game.
In response, Dragons number 10 Matthew Jones scored 11 points with the boot, their solitary try coming from Martyn Thomas, while replacement Jason Tovey landed a late penalty attempt.
Treviso's Kristopher Burton scored 18 points to send Ulster to a 23-12 defeat - their third successive league defeat and a first loss at Ravenhill since last December's defeat to Leinster.
Forward dominance gave Treviso the edge throughout and a penalty try at the end of the first half, along with Burton's intercept score after 67 minutes, gave Ulster no hope of clawing the game back despite two late tries from Pedrie Wannenburg.