John Tavares and Lubomir Visnovsky scored for the Islanders, who lost their second straight after going 5-1-2 in the previous eight games to get close to the eighth and final Eastern Conference playoff spot.
Montreal native Kevin Poulin made his second start of the season in goal for the Islanders to give starter Evgeni Nabokov a rest. The 22-year-old Poulin was called up from AHL Bridgeport on Feb. 23 when backup Rick DiPietro was waived and sent down.
Ryder opened the scoring with a power-play goal at 9:36 of the first, tipping a slap shot of the point past Poulin, whose only other start came in a 4-2 loss to Carolina on Feb. 24. It was the ninth goal of the year for Ryder, who was reacquired from Dallas earlier this season.
Tavares made it 1-1 at 12:06 with his 18th goal of the season on a slick move, faking a pass to linemate Brad Boyes and beating Price with a snapshot from the left circle. Tavares is tied with Pittsburgh's Chris Kunitz and Jeff Carter of Los Angeles, three goals behind league leader Steven Stamkos.
"We got away from our game after playing a good first 40 minutes," Tavares said. "We have to understand that we can't come off the gas pedal in the third period."
Visnovsky put New York ahead at 6:58 of the second when he tapped in a rebound with assists by Tavares and Matt Moulson.
Moulson assisted on both Islanders goals, and leads the Islanders with 21 assists
"All we can do is forget about this and come back tomorrow," Moulson said.
New York hosts Pittsburgh on Friday and Florida on Sunday before starting a four-game road trip. The Islanders are 8-4-1 on the road.
The Canadiens return home to play Buffalo on Saturday at the Bell Centre.
NOTES: Montreal played without Brandon Prust (shoulder) and scratched defenseman Tomas Kaberle. ... The Islanders scratched defensemen Radek Martinek and Joe Finley and forward Eric Boulton. ... Defenseman Matt Carkner made his return for the Islanders after missing 20 games with a groin injury. ... Islanders right wing Michael Grabner also returned, having missed three games with a shoulder injury.