May Bell guitar headstock

May Bell was a brand of the Slingerland Company.  Guitars were made by Harmony and Regal [Source: Bluesbox Collection ]

http://www.slingerlandguitar.com/

Image courtesy of Lowell Levinger , Players Vintage Instruments

images eBay:

1923 May Bell guitar

May Bell guitar

May Bell slot head

see Slingerland