The Amy Elizabeth (“Betty”) Blagg Collection of Bryozoa at the Museum of Comparative Zoology (MCZ) consists of 55 lots containing 33 genera (51 species) collected on the coast of California from 1936 to 1938. The collection was received at the Museum of Comparative Zoology in 1939, having been given by Blagg to then curator Elisabeth Deichmann while they were conducting summer research at Stanford University's Hopkins Marine Station. The Blagg specimens are now accessioned, photographed, and assigned unique MCZ catalog numbers, making their data newly available to researchers. Biographical details on Blagg (Amy Elizabeth Blagg Anderson 1905–1990) and information on Elisabeth Deichmann (1896–1975) are included.