It's a US-made Universal Mercury II, circa 1945. It makes about 65 exposures on standard 35mm film. The similar-looking Mercury I was made in the late '30s and used a special-size "#200" film made in Belgium (by Gevaert?) and sold by Universal; this scheme allowed them to make money on film sales as well as cameras.
The weird-looking arced enclosure on the top of the camera accommodated the semi-circular blades of its rotating focal-plane shutter, which offered speeds of 1/20 to 1/1000 sec.