The mollusca fauna of the Trenton Group, as represented in the Museum of Comparative Zoology (MCZ) collections, consists of: 23 genera and 3 species of nautiloids; 13 genera and 1 species of bivalves; 15 gastropod species; and 2 species of monoplacophoans. The specimens illustrated here were collected by Charles Doolittle Walcott and William P. Rust in the late 1800s. The Trenton mollusca fanua is mostly dominated by nautiloids and gastropods with bivalves and monoplacophorans being less dominant and in some cases quite rare. Specimens in the MCZ collections were recently identified by Kathleen Histon (nautiloids), John Pojeta (bivalves), and Peter Wagner (gastropods and monoplacophorans).