The Martin Centennial
"Centennial" means 100, so I'm assuming they mean the 100th anniversary of the saxophone: the serial number charts say the horns pictured here were made in 1942, so it's close (the original saxophone prototype, a C bass, was made by A. Sax in 1843).
This is possibly the rarest Martin model and may have only been produced for a year or two. The two examples that are in my directories have virtually identical serial numbers, which makes me tend to believe that. It's also probable that this was a specialty horn and other models were being produced at this time, as well.
Compare these horns to the Committee ("The Martin ___") models. These horns introduce a lot of the features found on those models, but the patents weren't yet finalized, so they still have some of the "flavor" of the Handcraft Committee II.
These horns are lacquer with silver keytouches, like the later Magna models. It is unknown if models were available in any other configuration. I also don't know if baritone models were available.