"Five Natural Hybrid Combinations in Minnows (Cyprinidae)" by Frank B. Cross and W. L. Minckley is a scientific publication written in the early 1960s. This book explores the occurrences of natural hybridization among several species within the minnow family (Cyprinidae) in North America, mainly focusing on various hybrid combinations observed during a drought in Kansas and Arkansas. The content of the book details five distinct hybrid combinations, including those between species such as "Chrosomus erythrogaster" and "Notropis cornutus frontalis", and observes their unique physical traits compared to their parental species. The authors discuss how environmental conditions, particularly a period of severe drought, may have facilitated the hybridization process due to increased spawning opportunities in concentrated habitats. Each hybrid is described in terms of anatomical characteristics, such as body structure, pigmentation, and organ morphology, emphasizing the intermediate nature of these hybrids and providing diagnostic traits for identification. The study contributes to understanding the implications of hybridization on fish diversity and ecology in changing environments. (This is an automatically generated summary.)