Panama, 1924, 5c on 10c Canal Zone registration envelope on buff, 165x95mm, used with a pair of 2c Arms (236) to Gatun, C.Z., cancelled violet "Agencia Postal, Panama, Mar 20, 1925" duplexes with a pair of Panama post office seals sealing the top and bottom of the envelope, purple "R/Agencia Postal, Panama" registry framed handstamp with blue "13507" handstamp, purple "Ancon, C.Z. Mar 30" backstamp, Very Fine and exceedingly scarce. Higgins and Gage No. C2  Estimate $750 - 1,000. This envelope was originally prepared as a 10¢ registration envelope for the Canal Zone. For some reason it was rejected, and the envelope was surcharged as 5c and the Canal Zone blacked out. They were then used in Panama for registered letters. $0 (Image)