[Illustration: FIG. 54.--Maya month-signs; upper rows from the monuments; lower rows from the MSS. A. pop. B. uo. C. zip. D. zotz. E. tzec. F. xul. G. yaxkin. H. mol. K. chen. L. yax. M. zac. N. ceh. O. mac. P. kankin. Q. muan. R. pax. S. kayab. T. cumhu. U. uayeb.] [Illustration: FIG. 55.--Maya period-signs. Upper row, face-signs; lower row, normal signs. A. cycle. B. katun. C. tun. D. uinal. E. kin.] Unlike the Mexican months, however, these were used in dating, and a given day was expressed with its month-sign, together with a numeral to show which day of the month it was. Thus 6. caban, 5. pop, means the day 6. caban, after 5 days of the month pop have passed. The numerals were not expressed on quite the same system as the Mexican. Dots were used for the numerals up to four, but a bar was used for five, two bars for ten, and so on, odd days over a multiple of five being expressed by the requisite number of dots. On the monuments, if the supernumerary dots were few, the space between or on either side of them was filled with small crescents, which are merely ornamental and must be carefully distinguished from the dots themselves. Occasionally in the more elaborate carvings the numbers from 0 to nineteen are expressed by faces. In the case of 0 the lower jaw is formed by a hand, and numbers over ten are expressed by the face assigned to the corresponding unit but with a fleshless jaw. Ten itself is the head of the death-god. Zero in the normal notation is expressed either by a hand or a figure shaped somewhat like a Maltese cross. The use of the zero is explained later. The Maya, like ourselves, were in the habit of expressing a high number by a succession of figures which combined to form a numeral, but they did not employ the decimal system. Their system, when applied to the computation of time, was on the whole, but not entirely, vigesimal, and was as follows. Twenty days, or _kin_, formed a _uinal_, and the uinal thus corresponded to one of their months; but the next higher unit, the _tun_, consisted of eighteen uinal, and contained 360 days, being thus equivalent to a year _minus_ the five uayeb days. Twenty tun made a katun (7200 days), and twenty katun went to another period of which the name is not known, but which is usually called a cycle (144,000 days). There are indications that a higher unit still was recognized, the so-called “great cycle,” consisting of thirteen cycles (1,872,000 days). Each of these periods was expressed by an appropriate glyph, and these glyphs were in two styles, being either what is usually termed “normal” signs, or face-signs (Fig. 55). The latter exhibit considerable variation, especially that of the great cycle; but the cycle bird-face is recognizable by the jaw-bone in the shape of a hand (recalling the face-paint of the Mexican gods into