LAST year Mr. J. L. Bosqui gave to the Geological Department of the British Museum part of a fossil shoal of herrings found in a marine deposit of diatoms, now being worked for commercial purposes as “celite” in Santa Barbara Co., California. The species represented has since been named Xyne grex by Professors Jordan and Gilbert, who exclude it from the genus Clupea on account of its thicker enamelled scales, enamelled opercular bones, and strong ventral scutes. The matrix, examined under the microscope, proved to consist so completely of diatoms and other siliceous organisms that it seemed desirable to submit them also to special examination. I was therefore fortunate in enlisting the services of Sir Nicholas Yermoloff, whose extended studies of such organisms make his determination and discussion of these new fossils of particular value. His notes form an interesting supplement to the following short account of the deposit, which was given by Dr. Frank M. Anderson to Professor Jordan (op. cit., p. 14):—