This paper contained a brief historical sketch of Ziphius cavirostris. The skull of a specimen caught at sea in 1870, off Hamna Voe, Northmaven, Shetland, was then described, and this skull was compared with previously recorded specimens. A brief historical sketch of Sowerby's whale was then given, a skull in the Edinburgh Museum of Science and Art was described, and reasons were advanced for associating it with the genus Mesoplodon rather than with Ziphius.