Introduction The initial systematic investigations of American algae - fossil and recent, microscopic and macroscopic, freshwater and marine - were conducted between 1837 and 1857 by Jacob Whitman Bailey (1811-1857), a professor of chemistry, mineralogy and geology at the United States Military Academy at West Point, New York. During this period of expanding and intensifying geographical and natural history explorations of the North American continent and the oceans of the world, Bailey served as the American focus for the investigations of the algae, especially the microscopic infusoria. Among his microscopic algal collections are samples from 1) fossil infusorial deposits from all over the North American continent, especially the eastern seaboard, 2) the early soundings of the U.S. Coast Survey, 3) the Wilkes' Exploring Expedition (1838- 1842) and the North Pacific Exploring Expedition (1853-1856), 4) the expeditions opening the American West of Fremont, Williamson, Newberry and others, 5) Berryman's soundings across the North Atlantic for laying the first transatlantic telegraph cable, and 6) his own extensive collections of algae from Nova Scotia to Florida. In addition, he communicated and exchanged samples extensively with American and European workers and thus procured a collection representing many regions of the globe. By the early 1840's Bailey had earned the accolade of "America's Ehrenberg", and by the mid-1850's he had amassed the finest and most extensive collection of algae in America. About two years before his death as a result of his increasingly failing health, he began to organize his collection for the use of those that would continue his work. Upon his death in 1857, Bailey bequeathed the collection, both organized and unorganized portions, plus the bulk