It turns out these glasses were made by Anchor Hocking, distributed as "Anchorglass". I found a set of four glasses that included a similar motif, still in their original box. Interesting that there are still a number of glasses with this design to be found, but I've never seen them identified as an Anchor Hocking product. I've contacted Oneida (which now owns Anchor Hocking), as well as a glass museum in Ohio (where they were manufactured) to see if any additional information is available, but nothing yet.