Update: Shortly after posting this blog post some POP contributors found some resources that indicate an 18th century Prior Scipio, who may be the owner associated with this stamp. View the links in the comments on Flickr here: https://www.flickr.com/photos/58558794@N07/16990667511/ and contribute your own comments if you can contribute more information.
A recent reference request came my way from a librarian at the Mullock Library in Newfoundland. He had found a stamp in several 18th century books that are a part of Jean Bolland’s Acta Sanctorum. The stamp he had found had the words “Scipio Prior de Guglielmis” on it, and there was a note of a stamp with the same words for a copy of another ecclesiastical book, the Decisiones Patavinae ( S-33.4.7).
An image of the Penn copy of the stamp (shown above) is now up on the POP Flickr feed, but there isn’t much known about the stamp itself, or who the Prior de Gugliemis might have been. Like many examples of stamps, the Penn copy has parts missing where the stamp didn’t make full contact with the page, so being able to verify the exact words that are meant to appear by comparing it with the same stamp found in other libraries is very useful. The imagery in the middle is unfamiliar to me. It seems to be composed of a crown, a pair of fleur de lis, and some kind of triangular shape (drapery?) and a cross bar.
If anyone out there knows more about this stamp and can help identify this mystery provenance mark, respond to this blog or make a comment on the POP Flickr feed!