von Scherling's Roman de Troie Miniatures

A week ago I mentioned and illustrated a pair of full-page miniatures from the earliest illuminated manuscript of the Roman de Troie, which were offered for sale, with the two shown above, by Erik von Scherling in his Rotulus catalogue, vol.IV (1937), no.1817:

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