Canal Zone, Airmail, 1931, 10¢, 40¢ and $1 Issues, used with 3¢ purple and U.S. 10¢ special delivery #E15a tied by Canal Zone roller cancel on cover to Silver City, S.D., Fort Amador return address, Balboa (6.11) and Miami (6.11) backstamps; some edge wear; F.-V.F., A scarce U.S. special delivery use from Canal Zone. Scott No. C9, C13-C14 + U.S. E15a  Estimate $200 - 300. $0 (Image)