It looks like the full serial number would start out 42-35 with some more digits after the 5. The tail seems to show a Triangle K, which would be the 379th BG.
42-3559 was from the 379th BG and according to the fortlog: (
http://www.91stbombardmentgroup.com/...ID/FORTLOG.pdf) it crash landed at Ambrieres-Les-Vallees, 25 miles N of Laval, France on 1 December, 1943.
That might be a possibility. Ambrieres-Les-Vallees is just north of Mayenne and "Mayenne" may be what is written on the 2nd line on the back of the photo.