At present, the CAS Diatom Collection has original sample material from over 18,000 locality records, 59,000 microscope slides, 55,000 taxa identified on slides, 8,400 diatom bibliographic references, and a database of 44,000 diatom species. The collection also houses important type material, with a total of 15 generitypes, and holotypes and isotypes for over 470 taxa, covering 128 genera (Kociolek et al. 1996). The locality, publication, and taxon database is available for searching the CAS holdings.


Dr. G Dallas Hanna established the Diatom Collection at the California Academy of Sciences in 1919. During his 51 year tenure in the Department of Paleontology, Hanna collected many fossil localities in western North America. These collections, which formed the backbone of the Academy’s diatom holdings, served as the material for his research program on the taxonomy and biostratigraphy of marine diatoms. With the publication of his many research articles, Hanna became the acknowledged leader and pioneer in applying diatom biostratigraphy to practical problems, including oil exploration. In addition to his own collections he received many diatom-bearing samples from prospective oil-drilling sites and well core samples, all of which included well-documented stratigraphic information. The notoriety Hanna achieved led to extensive correspondence with U.S. and foreign workers. Diatom materials were sent to Hanna from all over the world for his review, insight and interpretation. As a result, Hanna generated about 1200 samples and 9000 slides for the collection.


"Doc" Hanna’s interest and expertise in marine fossil diatom taxonomy and systematics inspired several collaborative efforts, including one with Albert Leon Brigger of Yucaipa, California. Brigger amassed a personal collection from correspondence with practicing diatomists (Reinhold, Kanaya, Lohman) and interested amateurs (Burke) as well as through purchases of collections, including the collection of W.F. Herzberg. In all, the Brigger Collection consisted of over 1900 samples and nearly 26,800 slides almost all of which were single mounts. An especially significant part of the Brigger Collection is the nearly 12,750 slides of the genus Aulacodiscus. The major portion of the Brigger Collection arrived at CAS in 1977.


The H.E. Sovereign Collection consists of 1081 slides from nearly 550 localities. Over 90% of the Sovereign Collection are from recent freshwater localities in Washington and Oregon, collected between 1924 and 1962. The Sovereign Collection includes 97 slides from the eminent German diatomist Fredrich Hustedt. Mahood (1978) detailed the Sovereign collection holdings.


Several other collections are part of the CAS holdings. The William Abbott Collection, comprising over 2300 samples and 4000 slides from well-documented marine fossil localities and geological sections. The Sam L. Van Landingham Collection, with 2154 slides made from nearly 1420 samples, is derived from recent and fossil freshwater collections. The W.I. Firth Collection of approximately 500 slides includes 89 slides of original William Smith material prepared by Sturt. The Forest Begres Collection of central U.S. freshwater habitats is a recent addition to the Academy holdings. The V. Porguen Collection contains approximately 650 samples from marine fossils deposits.


Several significant collections have recently arrived at the CAS Diatom Collection. The collections currently being accessioned into the Hanna Database include: the collections of G.W. Prescott, Wm.C. Vinyard, S.L. VanLandingham, S.R. Rushforth, J.P. Bradbury, and the US Geological Survey National Water Quality Assessment Program (NAQWA).