Supplement to the Catalog of Seals and Whales in the British Museum by John Edward Gray is an important source of information for the study and research of marine mammals. In this work, the author describes in detail the findings of seals and whales, which are kept in the collections of the British Museum, which allows scientists and specialists to get to know these sea creatures more deeply. The book contains illustrations and images that provide an opportunity to better understand the variety of species of seals and whales. "Supplement to the Catalog of Seals and Whales in the British Museum" will be a useful resource for those interested in marine biology and natural history.