Eleven of the Capital-based players are included in the forward pack, with Simon Berghan, Allan Dell, Ross Ford, Murray McCallum, Stuart McInally and WP Nel all selected by Gregor Townsend.
Back-row trio Magnus Bradbury, Jamie Ritchie and Hamish Watson are all included while Townsend has also called up Dougie Fife, Blair Kinghorn, Henry Pyrgos and Matt Scott.
The Scotland head coach has also invited wing Darcy Graham and flanker Luke Crosbie to train with the squad.
John Barclay and Mark Bennett both miss out through injury.
Townsend said: “We now begin the last 12 months of our preparations for Rugby World Cup 2019 with four Test matches in four weeks, a similar challenge to the one we’ll face in Japan.
“We’ve named a 40-man group for this campaign, which highlights the quality of player that is now available to us and the competition for places.
“It also enables us to welcome more players into our training environment and hopefully give a few more players a taste of Test match rugby.
“It’s going to be an exciting year for the squad but our primary focus is fixed on performing well against Wales – familiar opponents who have already recorded a win against us this year.”
Alex Allan (Glasgow Warriors), Simon Berghan (Edinburgh), Magnus Bradbury (Edinburgh), Fraser Brown (Glasgow Warriors), Allan Dell (Edinburgh), David Denton (Leicester Tigers), Matt Fagerson (Glasgow Warriors), Ross Ford (Edinburgh), Grant Gilchrist (Edinburgh), Jonny Gray (Glasgow Warriors), Rob Harley (Glasgow Warriors), Murray McCallum (Edinburgh), Stuart McInally (Edinburgh), Willem Nel (Edinburgh), Gordon Reid (London Irish), Jamie Ritchie (Edinburgh), Sam Skinner (Exeter Chiefs), Blade Thomson (Scarlets), Ben Toolis (Edinburgh), George Turner (Glasgow Warriors), Hamish Watson (Edinburgh), Ryan Wilson (Glasgow Warriors).
Alex Dunbar (Glasgow Warriors), Dougie Fife (Edinburgh), Chris Harris (Newcastle Falcons), Adam Hastings (Glasgow Warriors), George Horne (Glasgow Warriors), Pete Horne (Glasgow Warriors), Sam Johnson (Glasgow Warriors), Huw Jones (Glasgow Warriors), Lee Jones (Glasgow Warriors), Blair Kinghorn (Edinburgh), Greig Laidlaw (Clermont Auvergne), Sean Maitland (Saracens), Byron McGuigan (Sale Sharks), Ali Price (Glasgow Warriors), Henry Pyrgos (Edinburgh), Finn Russell (Racing 92), Matt Scott (Edinburgh), Tommy Seymour (Glasgow Warriors).