another is 200 tuns, or about 197 years. The distance from Katun 13 of one cycle to Katun 11 of the second following cycle is 280 tuns or about 276 years.

The coincidences of dates are remarkable when it is seen that the length of time from the first date of Piedras Negras to that of Chichen Itza is 278²⁄₃ tuns, while the time between the arrival at Chacnouitan to the removal to Chichen Itza is given by the Book of Chilan Balam as 280 tuns. More than this, if an inscription should be found hereafter in Piedras Negras recording a date as late as 54. 9. 13. 9. 6. 16, this would show a stay in Piedras Negras of 99 tuns, the time given in the manuscript for the stay at Chacnouitan, and if about 54. 9. 13. 9. 6. 16, the people of Piedras Negras deserted that city, they would have passed 204 years and 73 days before arriving at Chichen Itza. Now, all the historical dates of Quirigua lie between this last date and that of their arrival at Chichen Itza. Could the people of Piedras Negras have passed over to Quirigua and occupied that city during a part of this period of 204 years?