Alphonse Labitte (1853- )

I occasionally encounter catalogue descriptions which mention an anonymous bookplate, variously described by different cataloguers, but recognisable from its device/motto on the scroll below the shield "EXCELSIOR":

Baltimore, Johns Hopkins University, John Work Garrett Library, Gar 6
http://www.digital-scriptorium.org

Didier Petit catalogue online

Didier Petit de Meurville (1793-1873) of Lyon was one of the major French collectors of religious art of the 19th century.

A partially annotated copy of his sale catalogue: Catalogue de la collection formée par M. Didier Petit a Lyon ... Paris, Dentu, au Palais Royal, (1843), is available through Gallica, and an unannotated one through Google Books.