The most important addition to the knowledge of these whales made during the last quarter century was the discovery of representatives of the three genera _Mesoplodon_, _Ziphius_, and _Berardius_, at Bering Island, in the North Pacific, by Dr. Leonhard Stejneger, whereby the known range of the family was very greatly extended. Two of the forms were described by Doctor Stejneger in 1883, and the third by myself from a skull which he collected. About one-half of the material which the Museum possesses consists of that collected by Doctor Stejneger in Bering Island and that from the same locality presented by Mr. Nicholas Grebnitzki, Russian governor of the Commander Islands. About six years ago the National Museum received information and specimens from correspondents showing that the range of the three genera found at Bering Island extends to the eastern North Pacific, one genus (_Ziphius_) having been observed at Kiska Harbor, Alaska, another (_Mesoplodon_) at Yaquina Bay, Oregon, and the third (_Berardius_) at St. George Island, Pribilof Group, Alaska, and near Cape Mendocino, California. On the east and west coasts of the United States the only occurrences of beaked whales known to me are as follows: EAST COAST OF THE UNITED STATES. _Mesoplodon bidens_: Nantucket Island, Massachusetts. 1867. Skull in the Museum of Comparative Zoölogy, Cambridge, Massachusetts. _Mesoplodon europæus_: Atlantic City, New Jersey. March 28, 1889. Young male. Skeleton, cast, photographs, and viscera in the National Museum. North Long Branch, New Jersey. July 22, 1905. Adult female. Skull in the Museum of Comparative Zoölogy, Cambridge, Massachusetts. _Mesoplodon densirostris?_: Annisquam, Massachusetts. August, 1898. Young female. Skeleton in the Museum of the Boston Society of Natural History. _Ziphius cavirostris_: Charleston, South Carolina. 1865 (?). Young female. Skeleton in the National Museum. (Type of _Z. semijunctus_.) Barnegat City, New Jersey. October 3, 1883. Adult female. Skeleton and cast in the National Museum. St. Simon Island, Georgia. 1893. Male (?). Known from a photograph; only a few bones preserved. Newport, Rhode Island. October, 1901. Adult male. Skeleton and photograph in the National Museum. _Hyperoödon ampullatus_: New York Bay, New York. 1822. Female (?). Not known to have been preserved. North Dennis, Massachusetts. January, 1869. Male. Skeleton in the Museum of Comparative Zoölogy, Cambridge, Massachusetts. Newport, Rhode Island. 1869. Female. Skull in Museum of the Academy of Natural Sciences, Philadelphia. WEST COAST OF THE UNITED STATES.