"A New Bat (Genus Pipistrellus) from Northeastern Mexico" by Rollin H. Baker is a scientific publication written in the mid-20th century. The book presents a detailed study of a newly identified subspecies of the eastern pipistrelle bat found in northeastern Mexico. It contributes to the taxonomy and understanding of bat biodiversity in this specific region. The content of the book focuses on the description and classification of the newly recognized bat subspecies, named "Pipistrellus subflavus clarus". Baker provides extensive morphological data, including size and skull measurements, and contrasts this subspecies with other known varieties of the eastern pipistrelle. The study includes the geographic range of "clarus", primarily in Coahuila, Mexico, and parts of southwestern Texas, highlighting its habitat preferences along riverbanks with particular flora. Baker's meticulous observations aim to enrich the scientific community's knowledge of bat species, emphasizing the importance of preserving biodiversity in these ecosystems. (This is an automatically generated summary.)