I think SDC meant exactly what he wrote. The original semi auto prototype was the MAS 38, modified in 1939 by the MAS 38/39. This was followed by the MAS 40, which was actually adopted by the French Army about the time the Germans crashed the party.
Incredibly, development continued through the war years, and the MAS 44 was developed, followed after the war by the MAS 49 and 49/56.
The MAS semi autos are not conversions or modifications of the MAS 36 bolt action rifle; they are similar in appearance, but the semi-auto receiver is much larger than that of the MAS 36, and the whole gun is sturdier. Stocks are not the same, though they look the same at first glance.
The gas impingement system in the MAS semi autos is much like that of the Ljungmann; both are superior to the AR-15/M16 system because the spent gas is exhausted into the air, not directed back through the bolt carrier, which is a weak point in the Stoner design.