2. A complete skeleton and photographs of an adult male, 20 feet 1 inch long, obtained at Newport, Rhode Island, in 1901, through Dr. E. A. Mearns, Mr. L. di Z. Mearns, and Capt. Gus Soderman. Cat. No. 49599. 3. The collection contains also the skeleton of the young female individual obtained at Charleston, South Carolina, prior to 1865, which constitutes the type of _Hyperoödon semijunctus_ Cope. It was originally in the Charleston College Museum, but later was received by the National Museum in exchange. This individual was between 12 and 13 feet long. Cat. No. 21975. In addition, the national collections contain the following material, known to, or supposed to, represent the species _Z. grebnitzkii_: 4. Cat. No. 20993. Skull of a male (?).[37] Collected by Dr. L. Stejneger in Bering Island, 1882. Orig. No. 1521. Type of _Ziphius grebnitzkii_. 5. Cat. No. 21245. Skull. Orig. No. 1758. 6. Cat. No. 21246. Skull. Orig. No. 2531. 7. Cat. No. 21247. Skull. Orig. No. 1849. 8. Cat. No. 21248. Skull of a male (?). 9. Cat. No. 83991. Skull. The five skulls preceding were also collected by Doctor Stejneger in Bering Island in 1882 and 1883. 10. Cat. No. 22069. Skull of a female (?).[37] 11. Cat. No. 22874. Skull. 12. Cat. No. 22875. Bones of an immature individual. These three specimens were collected and presented by N. Grebnitzki. 13. Cat. No. 142579. A series of photographs of an individual captured in Kiska Harbor, Alaska, September, 1904. Presented by Dr. J. Hobart Egbert. 14. Cat. No. 84906. Photograph of the skeleton of an individual washed ashore at St. Simon Island, Georgia, in 1893, and belonging to Mr. W. Arnold. In the genus _Ziphius_, as in other ziphioid genera, a study of the characters of the skull appears to afford the best basis for discrimination of species. We have first to consider whether the North American species is the same as the European and New Zealand species, and afterwards whether the North Pacific species is identical with or distinct from these. The published measurements of specimens from the coasts of Europe and New Zealand, currently believed to represent the single species _Z. cavirostris_, are rather meager, and, furthermore, prove, on examination, to present so little uniformity that they are of limited use for comparison with measurements of skulls from the Atlantic coast of the United States. About all that can be said is that the latter skulls are of about the same size as the former and that the proportions do not present any striking differences. For detailed measurements of the American skulls, see page 53.