Internal airmail cover franked with 1930 4c on $3 green 'Interior' AIR issue and 1c olive green 'Tax' issue (SG 258 & 223) tied by COBAN cds's dated MAR26 1931 with large SERVICIO EXPRESO 5 PM 26 MAR 1931 cancel alongside in black. Addressed to GUATEMALA CITY with arrival cds of the same day with 6.30PM time slug. Scarce genuine Express mail most likely transported by car.