Joseph Leidy was the leading American expert on anatomy and vertebrate paleontology during the mid nineteenth century and author of over 200 scientific texts. Philadelphia's Academy of Natural Sciences, where Leidy worked, is fortunate to have a great portion of Leidy's collections. The Academy has put together this nice, illustrated site on Leidy's important work. The section on fossils includes a hypertext list of specific names with links to photographs, illustrations, and descriptions of the specimens. Be sure not to miss the section on the duckbilled dinosaur Hadrosaurus foulkii, the subject of Leidy's best known monograph. Other highlights are an overview of Leidy's other scientific work, including forays into parasitology and protozoology and his Professorship in Anatomy, a timeline biography, and a thorough index.