GRATACAP, Louis Pope, naturalist, born in Brooklyn, New York, 1 November, 1850. He was graduated at the College of the City of New York in 1869 and at the Columbia school of mines in 1876. Subsequently he received the appointment of assistant curator in paleontology and mineralogy in the American museum of natural history in New York, where the arrangement of the specimens in the present building was largely conducted under his supervision. Mr. Gratacap has also held the office of chemist to the Metropolitan gaslight company in New York for many years. He has been a large contributor to scientific journals, and, besides botanical notes in the" Bulletin of the Torrey Botanical Club," has published a series of papers on "The Ice Age" in the Popular Science Monthly for 1878, a series on " Gas and Gas-Making " in the " Scientific American Supplement" (1880), and a valuable series on archaeology in the "American Antiquarian" (1883-'4). Mr. Gratacap is also the author of " Philosophy of Ritualism, or Apologia pro Ritu" (New York, 1887).