AN appreciation by C. Hart Merriam in Science of April 8 of Dr. William Henry Dall, reminds us than by the death of this veteran conchologist on Mar. 27 last, zoology is deprived of one of the last remaining naturalists of the old school. Although chiefly known as a student of the Mollusca, Dr. Dall's activities were by no means confined to this group, his papers and monographs on a variety of subjects all ranking high in scientific literature. His earlier work was chiefly on the natural history of Alaska, which he visited as one of the scientific staff, and later as head, of the Western Union International Telegraph Expedition. Besides exploring and mapping much of the Yukon River, he found time for observations on birds, fishes, and whales, the results of which, as well as geographical works on Alaska, were all published before 1880. From 1871 until 1874, Dr. Dall was surveying the Aleutian Islands and adjacent coasts; from 1880 until his death he was honorary curator in the National Museum, and palaeontologist of the United States Geological Survey from 1884 until 1925. From 1893 until 1927 he held the chair of invertebrate palaeontology in the Wagner Institute of Science, from 1899 until 1915 was honorary curator of the Bishop Museum, Hawaii, and in 1899 again visited Alaska with the Harriman Alaska Expedition as one of the scientific guests. Dr. Dall's unique experiences thus render his works peculiarly valuable, whether he is remembered as a zoologist, palaeontologist, or explorer.