A Distributional Study of the Amphibians of the Isthmus of Tehuantepec, Mexico by William Edward Duellman is a comprehensive investigation of the amphibian species found in the Isthmus of Tehuantepec, a narrow land bridge in southern Mexico that separates the Pacific Ocean and the Gulf of Mexico. This study focuses on understanding the geographic distribution, ecology, and diversity of amphibians in this biologically rich but understudied region.Duellman begins by describing the physical and climatic characteristics of the Isthmus of Tehuantepec, which includes various habitat types such as tropical rainforests, dry forests, swamps, and highland areas. These diverse ecosystems create distinct niches for different amphibian species, allowing for a rich variety of species to inhabit the region.