The region covered by this study, the southern segment of the Gulf coastal plain of Mexico and the adjoining coastal plain of Mexico and the adjoining coastal plain of Nuclear Middle America, is not uniform in respect to its flora and fauna. This tropical lowland region is divided into three biotic provinces: the Veracruz, which roughly coincides with the political boundaries of the state of Veracruz; the Yucatán, which coincides with the state of Yucatán and the coastal portion of Campeche; and the Petén, which covers the Yucatán Peninsula (L. C. Stuart, 164: 349). Of these three, Yucatán province is probably the most distinctive, influenced by its greater aridity. Although the fauna varies throughout this lowland region, most of the animals that were used are found in their appropriate habitats throughout. In those cases in which one species or genus is not found throughout the region, for purposes of analysis I have combined it with an ecotype so that together they range throughout. For example, the two species of peccary are combined; together they occur throughout the region, whereas singly they do not. This was done in an attempt to eliminate the effect of animal distribution on patters of animal use.