Martin Model 201 - design project only, 2-engine high speed attack/bomber (slim fuselage with fore/aft engines in line driving contra-rotating props)
Martin Model 202 - 2-engine civil transport, aka Martin 2-0-2
Martin Model 203 - design project only, 4-engine high altitude heavy bomber
Martin Model 205 - designation for planned Martin built production of Northrop B-35 'Flying Wing'
Martin Model 206 - design project only, 2-engine patrol bomber
Martin Model 207 - design project only, 2-engine long-range escort fighter*
Martin Model 208 - designation for planned Martin built production of Boeing PBB-1 Sea Ranger
Martin Model 209 - design project only, 4-engine long-range bomber
Martin Model 210 - AM Mauler
* intended for the same requirement that resulted the North American P-82 (I think)