This is a zoological book. Yellow bats occur only in the New World and by most recent authors have been referred to the genus Dasypterus Peters. The red bats and the hoary bat, all belonging to the genus Lasiurus Gray, also occur only in the New World except that the hoary bat has an endemic subspecies in the Hawaiian Islands. The kind of yellow bat first to be given a distinctive name was the smaller of the two species that occur in North America. It was named Nycticejus ega in 1856 by Gervais on the basis of material from the state of Amazonas, Brazil, South America, but was early recognized as occurring also in North America (in the sense that México and Central America, including Panamá, are parts of North America). More than 40 years elapsed before subspecific names were proposed for the North American populations.