The Maya Indians adapted the periods of Venus to agree with the lunar months:

 phase

observed periods

periods in the Mayan 'map'

difference

morning star

263

236

- 27

black

50

90

+ 40

evening star

263

250

- 13

black

8

8

0

sum

584

584

0

236 (= 8 * 29.5) appears in G. We cannot automatically, though, identify side a with the morning star season, because the true period is 263 (the same for the morning and evening stars).

Finding 250 as the glyph immediately before the supposed Venus glyph could mean it is the evening star period which has come to its end.