GIBSON manufactured the HG-20 (HAWAIIAN) between 1929 and 1933. It had a dreadnought shaped body with a central round sound hole and four other f-shaped sound holes at the corners of the instrument. Inside the body are two sound chambers - the central one is positioned under the round sound-hole and there is an outer one beneath the f-holes. Although they were sold as Hawaiian guitars for lap style playing (hence the HG name), most were sold set up for Spanish style playing with frets but with an added high nut adjuster in case you wanted to use a slide. These came supplied with or without a pickguard (which was perhaps more useful for Spanish style players). These were not made in great numbers and most examples seen today are setup for Spanish style playing - however this was the first example of the body shape that became the J-style.
Source: http://www.guitarhq.com/hg.html