Note 18 — II. The Mathematical Elements.
Reading edition
According to Pousse (Archives de la Soc. Amer. de France, 1887, p. 165), it is used to designate the particular day which falls on the 20th of the month, that is, the last day of the month, and has therefore the sense of “last,” “final,” rather than of 20. It is written as an affix to the month sign. Thomas states that it is used with month symbols “only where the month (of 20 days) is complete or follows one completed.” Amer. Anthropologist, Vol. VI, p. 246. There is some doubt whether No. 4 is not an element of union. Compare Seler, Zeitschrift für Ethnologie, 1887, p. 57.