"A Taxonomic Study of the Middle American Snake, Pituophis deppei" by William E. Duellman is a scientific publication written in the mid-20th century. This work focuses on the classification and differentiation of the snake species Pituophis deppei, particularly in the context of its populations in the Mexican state of Michoacán. The book lays out the findings from field studies, museum specimen examinations, and taxonomic reviews of historical literature related to this species and its subspecies. In this detailed taxonomic study, Duellman examines various relationships within the Pituophis deppei complex, including its subspecies and their morphological variations, particularly in terms of coloration and scale counts. The author presents evidence that supports the existence of distinct species and subspecies through careful analysis of over a hundred museum specimens as well as field observations. The study also includes historical perspectives on the classification of these snakes, nuances in geographical distributions, and a comprehensive examination of the scale and color variation among populations, contributing valuable insights into the biodiversity and ecology of Middle American snakes. (This is an automatically generated summary.)