Type section exposures at the Don Valley brickyard and Scarborough Bluffs were studied for ostracode occurrences. In all, 12 species were identified from the Don Formation, with Candona rawsoni and Candona caudata being most abundant. A deltaic environment, with a mixture of fluvial and lacustrine species, is indicated at the brickyard, whereas a more dominantly lacrustrine environment, with fewer ostracode species, is evident at the bluffs. Climatic indications are consistent with those of other fossil groups in suggesting conditions rather like the present.The Scarborough Formation has yielded only four species of ostracodes, with Candona caudata the most abundant. A much colder lacustrine environment is indicated for the Scarborough than for the Don Formation.