What is the name of that Instrument?

In the scene where about 30 soldiers are walking Kathryn Grayson's character home after the first night at the dance hall,the second line of men are playing a flute type instrument. Looks like fired clay and dark if not black in color. I've seen this instrument in other movies as well. What is this instrument??? Can't seen to get my hands on info about it simply because I can't figure out how to run a search for it. Help. Thanks, in advance,for any info you may have about this instrument.