This catalogue brings together some of the finest natural history drawings executed for Cassiano, including 251 coloured drawings of fauna, and 63 of gems, marbles, fossils and other natural curiosities. Cassiano had a particular interest in ornithology, and birds are thus the best-represented members of the animal kingdom in this group, with more than 200 drawings of both native and exotic species. Other drawings of fauna catalogued here include mammals, fishes and crustaceans. Like the bird drawings, many are drawn with painstaking attention to detail and scale, a complete specimen drawn on a reduced scale to fit the sheet, with anatomical details depicted life size. The drawings of mineral specimens and other natural curiosities depict the sort of item commonly found in seventeenth-century collectors' cabinets: gemstones, bezoars, marbles, corals, 'Lucifer' stones, fossils, exotic seeds and beans, as well as scientific instruments.