I believe what you have is a model 24. I also have a Cz 24 that has the "C 'up arrow' 26" on the slide. The '26' is not the model designation as they didn't put model numbers on their pistols back then. I believe it's the production year.
Also a letter followed by a 'Lion' followed by a number(E LION 26) would be the year it was accepted into military service.
Look for a copy of 'Know your Czechoslovakian Pistols'. Lots of good info there. You can also Google Cz 24 for more.
CZ22, CZ24, CZ27, CZ28, CZ36, CZ38, CZ45, CZ46, CZ50, CZ52, CZ75, CZ82, CZ83, CZ85, DUO, Mars, Z, M1922, Praga, Praha, Slavia, Little Tom, VZ24, VZ33, VZ52, VZ52/57, VZ527, VZ54, VZ58, VZ98/22, ZKM451, ZKM455S