Bowl with attached plate marked "Wallace 938"

Found this beautiful (albeit tarnished) silver bowl at a thrift store. Can’t find anything about it online. I assume it’s silver plated and not sterling because it doesn’t feel extremely heavy, but I cannot figure out what the 938 on the bottom means. The only place I’ve ever seen that before is in German sterling silver, but Wallace is an american company.
Wallace bowl 2.jpg
Wallace bowl.jpg