The Montreal Canadiens have activated goaltender Jake Allen and centre Christian Dvorak from the injured list on Thursday before their game against the Dallas Stars.
In corresponding moves, the team sent Cayden Primeau and Jesse Ylönen to the Laval Rocket. Primeau was an emergency recall when Andrew Hammond got hurt, so with the emergency condition gone, he had to be sent down.
Ylönen being sent down while Mathieu Perreault is still on waivers indicates that that team put Perreault on waivers to facilitate a trade or to gain a contract spot rather than a roster spot.