Here's what I had in mind when I was musing over the 'rum' symbol and the evolution of writing in the 17th and 18th centuries:
This says "florum". The "r" part is a hump shape (the rounded "r"), followed by a shape that looks like an "x" (a crossed descender). Togther it makes the suffix 'rum'.
But if you lived in an age where scribal abbreviations were disappearing, and typesetting was taking over (some symbols were dropped and others had substitutions), it might seem natural (to someone familiar with typesetting), to substitute an "x" for the "-um" part (since the "r" part could be substituted with a normal letter). They retained certain symbols for a while (like the ubiquitous y abbreviation) but even those gradually disappeared.
This says "florum". The "r" part is a hump shape (the rounded "r"), followed by a shape that looks like an "x" (a crossed descender). Togther it makes the suffix 'rum'.
But if you lived in an age where scribal abbreviations were disappearing, and typesetting was taking over (some symbols were dropped and others had substitutions), it might seem natural (to someone familiar with typesetting), to substitute an "x" for the "-um" part (since the "r" part could be substituted with a normal letter). They retained certain symbols for a while (like the ubiquitous y abbreviation) but even those gradually disappeared.