I got these many years ago, they were in a large lot that included Bausch & Lomb Microscopes and parts. The Lenses in the front row are unmarked but I believe they are prototypes made by Bausch & Lomb because there are NO markings of any kind on any of these Lenses except for one early Crico 18mm Lens. They date from the mid 1800's right when Baush & Lomb started making Microscopes. Some in this lot are from various time periods but the bulk is early Prototypes. These are very rare and hard to find. I have partial early Microscopes in an other listing that came from the same lot I bought. Very early Bausch & Lomb Lenses, these belong in a Museum.