The various peoples inhabiting Mexico and Central America in early pre-Columbian times were accustomed to record various events, especially in regard to their calendar and the religious ceremonials in relation to it, on long strips of skin or bark. These were usually painted on both sides and folded together like a screen. Several of these codices are still in existence from the Nahua and Zapotec areas in Mexico, but only three have come down to us from the Maya region which is included in the peninsula of Yucatan, the states of Tabasco and Chiapas in Mexico, and portions of Guatemala and Honduras. These three manuscripts are the Dresden Codex in the Royal Public Library at Dresden, the Tro-Cortesianus (formerly considered to have been two, the Troano and the Cortesianus) in the National Archaeological Museum at Madrid, and the Peresianus in the National Library at Paris. These pre-Columbian manuscripts have all been published in facsimile. (See bibliography.) These remains of a once extensive literature show evidence not only of considerable intellectual attainments on the part of their authors but also of a high degree of artistic skill in the drawings and hieroglyphics. The frequent occurrence in these manuscripts of representations of animals showing various degrees of elaboration and conventionalization has led us to undertake the task of identifying these figures as far as possible and studying the uses and significance of the several species, a field practically untouched.[284-*] Förstemann in his various commentaries on the Maya codices (1902, 1903, 1906), Brinton (1895), and deRosny[TN-3] (1876) have only commented briefly upon this side of the study of the manuscripts. Seler (1904a) and some others have written short papers on special animals. During the preparation of this paper there has appeared a brief account by Stempell (1908) of the animals in the Maya codices. The author has, however, omitted a number of species and, as we believe, misidentified others. In making our identifications we have given the reasons for our determinations in some detail and have stated the characteristics employed to denote the several species.