I don't think so, the top frame tubes are a bit too far apart. CWC used a similar chain ring, but skip tooth. 99% of Monarks were standard 1/2" pitch. Could be a CWC, or a mutt, not a terrible deal though. -Adam
Doesn't look like a Monark or CWC to me. Hard to tell from the one picture, but the chain stays look wrong for a Monark. The chain guard might provide a clue.