Maple Leaf Rag / Terrible Blues ? (Edit: Lu Watters)

Just came across this record with plain white, typewritten labels...not unlike some party records...that I have had since I first started collecting in California over 15 years ago.

I do not have the ability like some who can recognize musicians by ear.

Does anyone have a clue as to who these sides might be by?

Maple Leaf Rag has imprinted in the dead wax..."JMS-1" while Terrible Blues has..."MLB-121."

Edit: Many thanks to Jim VanDrisse & Yves François for identifying the personnel:

Maple Leaf Rag: Lu Watters (tp) Turk Murphy (tb) Bob Helm (cl) Paul Lingle (p) Pat Patton (bj) San Francisco, CA., 1939

Terrible Blues: Lu Watters (tp) Bob Scobey (tp,vcl) Turk Murphy (tb) Ellis Horne (cl) Wally Rose (p) Clancy Hayes, Russ Bennett (bj) Squire Girsback (tu) Bill Dart (d)
San Francisco, March 29, 1942