month names

[Anton]

Summarizing the discussion above, here's the explanation that looks consistent to me.

The year begins with March, so the series of the diagrams starts with March.
The start of March is under the sign of Pisces (in the Ptolemaic astrological system) - this also applies for the Julian calendar effective in the beginning of 15th century - so the sign of Pisces is depicted.
Similar logic applies for each subsequent month.

The person who added month names discerned this logic (and put down the correct month names).

Later readers of 20th century onwards were confused by the astrological signs and concluded that the series represents the astrological cycle (as opposed to the calendar cycle).