And where is such evidence to be found? Though there are several Spanish writers who lived in the sixteenth century who have written on the Nahuas, Bishop Landa is the earliest Spanish authority who has dealt with Maya customs and history. And the only Maya authorities of an early date that the student has access to are the papers contained in Brinton’s Maya Chronicles, the principal of which are the Books of Chilan Balam, which Dr. Brinton declares “to constitute about all that remains to us ... of the ancient history of the peninsula” as far as he knows. Yet, in making objection to certain views of Dr. Seler, Dr. Förstemann says, “It is based on certain statements in the Books of Chilan Balam, a very dubious source according to Seler’s own assertion.” I am at a loss to know why such sweeping condemnation should be made of these books, for though the copies from which Dr. Brinton quotes may not be very old, these copies hand down to us records which must be of very great age. Dr. Förstemann himself quotes from them with approval, and it is certain that whatever may be their historical value, the evidence which they give incidentally cannot fail to be of great value. This evidence will, I think, prove-- First, that the period of 20 times 360 days was called a katun and not an ahau. Second, that each of the constituent parts of a katun was called a tun. Third, that no such period of time as an ahaukatun is mentioned in the Books of Chilan Balam. The first assertion may seem difficult to prove when in far the larger number of cases where a separate katun is mentioned in the Books of Chilan Balam the word “ahau” seems to be substituted for “katun.” This is true in all five of the Books of Chilan Balam published by Brinton. But the reason of this is very evident, for it will be seen by a careful perusal that the word “ahaus” is never used when katuns in general are spoken of, and that whenever the word “ahau” is apparently given as a synonym of “katun,” it is merely the name of a particular katun and it always has a number attached to it and this number is the number of the day ahau with which a given katun ended. Further, this number is never an ordinal number, as translated by Brinton, but a cardinal number. Therefore 1, 2, 3, 4, 5, 6, etc. should be substituted in Brinton’s translation for 1st, 2d, 3d, 4th, 5th, 6th, etc., and in the quotations from Brinton this substitution is made.