DESCRIPTION OF THE SKULL OF MEGAPTERA MIO-CAENA, A FOSSIL HUMPBACK WHALE FROM THE MIOCENE DIATOMACEOUS EARTH OF LOMPOC, CALI-FORNIA.i By Remington Kellogg. Of the Bureau of Biological Survey, Department of Agriculture. INTRODUCTION. In the summer of 1919 the United States National Museum re-ceived through the United States Geological Survey a skull of a Miocene whale, which had been presented by the Celite Products Company, Lompoc, California. More recently the writer was en-abled to visit this particular locality, and through the courtesy of E. B. Starr and Edward J. Porteous, of the company, he was shown the exact position where the skull was excavated. The beds of diato-maceous earth at Lompoc furnish a very extensive marine fauna, composed mainly of fishes and to a less extent of birds, cetaceans, and pinnipeds. A very interesting account of the locality has recently been published by David Starr Jordan.^ In preparing to study the Tertiary Cetacea of the Pacific coast of North America, the writer had occasion to examine the literature relating to the described forms. The two principal accounts of the finding of fossil whales of the family Balaenopteridae in California are very brief, and without having examined the original specimens one can not be certain that the identifications are correct. In 1872 Cope ^ recorded the occurrence of Eschrichitus davidsonii in a forma-tion assumed to be of Miocene Age at San Diego, California. Some years later Stephen Bowers * announced the discovery of Escrichtius davidsoni [=? Balaenopfera davidsoni Scammon"] associated with other Pleistocene mammals at Ventura, California. 'This paper has been prepared in the course of a study on the fossil cetaceans of the Facific coast and is published here in advance of a final monograph on the subject. This study has been made possible by a grant from the Carnegie Institution of Washington and is being carried on under the direction of Dr. John C. Merriam. 'Jordan, D. S., A Miocene catastrophe, Natural History, vol. 20, no. 1, pp. 18-22, with illus.. New York, Jan.-Feb., 1920. s Cope, E. D., Proc. Acad. Nat. Sci. Philadelphia, pp. 29-30, 1872. * Bowers, S., American Geologist, vol. 4, p. 391, 1889. B Scammon, C. M., Proc. Calif. Acad. Sci., vol. 4, no. 20, pp. 269-270, San Francisco, Oct. 4, 1872. No. 2435-PROCEEDINGS U. S. NATIONAL MUSEUM. VOL. 61. ART. 14. 20107— 22— Proc. N. M. vol. 61 1 7 1