A decent bowl back case is like a hens tooth, as often times these instruments would come with a bottom loading case that would simply fall a part after a few decades (let alone a century in some instances).
This here is a fairly impressive "harder than average" chipboard case, suitable for a bowl back mandolin. Cosmetically its in good condition with strong latches and a clean interior. The dimensions are listed below:
Total interior length: 25.25"
Length from base to heel pocket: 15.5"
Width across face of top: 8.25"
Depth of bottom of case: 6.5" (lid depth adds approximately .75")
Depth of bottom of case at heel: 2" (lid depth adds approximately .75")