I would guess there were a couple hundred (maybe more?) record 
companies/labels
that existed for a year or a few during the 1919-1929 period, and then 
disappeared
without assigning their copyrights to anyone...?! The best known of these 
was, of
course, Grey Gull (et al)?! They disappeared around October 1930; however,
there was a following operation that contined pressing Madison, Radiex, Van
Dyke (and NOT Grey Gull...although that operation may have kept pressing
a few of the earlier GG records...?!). I am STILL trying to find out who was
behind the 1930-31 continuance of the GG labels; I suspect it may have been
the same operation that pressed Crown records for Woolworth's...?!

Steven C. Barr