___________________________________________________
Plate 51_b_. || Plate 52_b_.
--------------------------++---------------------------------------
X Oc. | II Ezanab. || | XI Cib. | VI Been.
XI Chuen. | III Cauac. || | XII Caban. | VII Ix.
XII Eb. | IV Ahau. || [Picture.] | XIII Ezanab. | VIII Men.
VIII | VII || | VIII | VIII
17 | 8 || | 17 | 17
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As before stated, the interval between 10 Oc and 2 Ezanab is 7 months and
8 days, as indicated by the red and black numerals under the latter.
According to the red and black numbers under the column commencing with
11 Cib, the interval between 2 Ezanab and 11 Cib should be 8 months and
17 days, the usual difference, when, in fact, as we see by counting on
the calendar, it is 8 months and 18 days. That this variation cannot be
attributed to a mistake on the part of the author or of the artist is
evident from the fact that the interval between 11 Cib and 6 Been (first
of the next column) is 8 months and 17 days and that the difference
throughout the rest of the series follows the rule given; that is to say,
each is 8 months and 17 days, except at two other points where this
variation is found and at the regular intervals where the difference of
7 months and 8 days occurs.[319-1] Precisely the same variation occurs on
Plate 55_b_ in passing from the first to the second column and on Plate
56_b_ between columns 1 and 2.

Why these singular exceptions? It is difficult, if not impossible, for
us, with our still imperfect knowledge of the calendar system formerly in
vogue among the Mayas, to give a satisfactory answer to this question.
But we reserve further notice of it until other parts of the series have
been explained.

Reference will now be made to the three lines of black numerals
immediately above the day columns. Still confining our examinations to
the lower divisions, the reader's attention is directed to these lines,
as given in Tables VI, VII, IX, XI, XIII, XV, XVII, and XIX. As there are
three numbers in each short column we take for granted, judging by what
has been shown in regard to the series on Plates 46-50, that the lowest
of the three denotes days, the middle months, and the upper years, and
that the intervals are the same betw