And while we're on the topic, I have Martin bowlback #2263, which would date to around 1907 according to the Mugwumps site. It's quite plain, with only 9 ribs and a simple, undecorated tortoise-celluloid pickguard. Markers only at frets 5, 7, and 10 (no 12th fret marker!) It's rather scratched up but sounds nice.
What model d'you suppose it is, with only 9 ribs?