I don't mean to butt in here, but it seems to me that Alan's point is that the bayonet camera mount isn't a screw. It does consist of interrupted lugs, but the lugs aren't the remnants of threads of a screw.

I'm no engineer, but a screw is an inclined plane wrapped around a cylinder, and it tightens (or loosens) the parts as it turns. The Webley screw grip (A&W C) clearly performs this function. You can see the screw clearly from the front of the breech, looking into the recess for the doll's head rib extension. I don't think the bayonet mount of a camera lens does anything of the sort.

What about it, guys? Is this the distinction?

Best,
Curl