The "dot & dash" pattern of perforations in the resonator flange looks like Stromberg-Voisinet, the predecessor of Kay -- major Chicago producer of inexpensive and mid-range instruments. Lots of instruments were built by the big American manufacturers, for sale by various distributors, or through catalogs. Many had no maker logos, though as Jim G points out, some had information stamped into the dowel stick that runs through the shell.
Bell Brand tailpieces are found on a lot of US-made instruments from the early 20th century.
Gibsn: '54 F5 3pt F2 A-N Custm K1 m'cello
Natl Triolian Dobro mando
Victoria b-back Merrill alumnm b-back
Stradolin Vega banjolin
Sobell'dola Washburn b-back'dola
Eastmn: 615'dola 805 m'cello
Flatiron 3K OM