Wells has made 91 starts in 117 games in 10 seasons in the NFL.
The 6-foot-4, 305-pound Snow is an undrafted rookie out of Texas who spent Sunday's 19-16 victory over the Arizona Cardinals on the active roster, but did not play and was bounced back to the practice squad.
Earlier in the day the Bills ruled out offensive tackle Cordy Glenn, guard Kraig Urbik and defensive end Mark Anderson for Sunday's game against the Tennessee Titans. Cornerback Terrence McGee, safety Da'Norris Searcy and defensive linemen Kyle Williams and Spencer Johnson are questionable.
Copyright 2012 by The Associated Press