Fit-again Gray back for Scotland
The experienced second-row forward returns from long-term back and calf injuries to be named in Townsend's revised squad ahead of their final two fixtures against Ireland and Italy, with 10 players added in total.
Alex Dunbar, Zander Fagerson, Darryl Marfo and Fraser Brown are also recalled after injuries, while George Horne has been handed a first senior call-up.
Scotland, who play unbeaten Ireland in Dublin on Saturday, are third in the Six Nations table after beating England 25-13 at Murrayfield on February 24.
Forwards: John Barclay (captain -Scarlets), Simon Berghan (Edinburgh), Jamie Bhatti (Glasgow), Magnus Bradbury (Edinburgh), Fraser Brown (Glasgow), David Denton (Worcester), Cornell du Preez (Edinburgh), Zander Fagerson (Glasgow), Grant Gilchrist (Edinburgh), Jonny Gray (Glasgow), Richie Gray (Toulouse), Luke Hamilton (Leicester), John Hardie (Edinburgh), Scott Lawson (Newcastle), Darryl Marfo (Edinburgh), Stuart McInally (Edinburgh), Willem Nel (Edinburgh), Gordon Reid (London Irish), Tim Swinson (Glasgow) Ben Toolis (Edinburgh), Hamish Watson (Edinburgh), Ryan Wilson (Glasgow).
Backs: Mark Bennett (Edinburgh), Alex Dunbar (Glasgow), Nick Grigg (Glasgow), Chris Harris (Newcastle), Stuart Hogg (Glasgow), George Horne (Glasgow), Pete Horne (Glasgow), Ruaridh Jackson (Glasgow), Huw Jones (Glasgow), Lee Jones (Glasgow), Blair Kinghorn (Edinburgh), Greig Laidlaw (Clermont Auvergne), Sean Maitland (Saracens), Byron McGuigan (Sale), Ali Price (Glasgow), Henry Pyrgos (Glasgow), Finn Russell (Glasgow), Tommy Seymour (Glasgow)