On the other hand, the text can also be read to have a '34th' (and now probably definitely last) period with yet 3 more glyphs:

'34'
	Ga7-18	Ga7-19	Ga7-20

The structure for the number of glyphs does not, however, support integrating also these 3 glyphs. Unless, we add glyphs before the 1st period:

'0'
	Ga2-24	Ga2-25	Ga2-26

The number of glyphs then becomes 73 + 63 = 136, which can be read as the conjunction of 13 (as in 13 * 28 = 364) and 6 (as in 180 / 30).

Considering the calendar to be a yearly cycle 'cut up' into parts like a 'serpent' - a string of glyphs representing 362 + 6/2 = 365 days - it is obvious that the 3 extra glyphs at the end (Ga7-18--20) will join to the 3 extra glyphs at the beginning (Ga2-24--26).