This derailleur is almost identical to my Ludoal Gran Sport, except for the outer parallelogram plate. On my Gran Sport the outer parallelogram plate has a touch of Campagnolo baroque and the words 'Ludoal Gran Sport'. On this derailleur the outer parallelogram plate has a highly stylised engraved image of a bird.
This bird logo is clearly derivative of the bird logo that the German airline, Lufthansa, uses on the tail of its aeroplanes. Lufthansa's logo was designed by Otto Firle in 1918 and depicts a flying Crane. Strangely one of the leading derailleurs of the 1970s was the Shimano Crane (DR101). God only knows what is going on here - but I like it.