mid century vintage folio of Audubon birds for framing or display, 50+ prints

Audubon Birds of America prints, mid 20th century vintage, in worn folio case. This is marked '50 selections', but there's more than 50 sheets here, and some I know are duplicates. I'm not sure if the original set is complete, with extras? Or if it's most prints from a couple of sets.

Lots of pretty prints here, in any case! These do have some yellowing from age, and some of these have soil marks. Most are still very nice, for framing or other art projects. Size is 9" x 12".