Abstract: This paper describes the mollusks and echinoids found in limestone dredged from ditches along the Tamiami Trail in southern Florida, in the area mapped as "Lostmans River limestone (Quaternary)" by Sanford but included in the Pliocene Caloosahatchee formation by Cooke and Mossom on the evidence of these fossils as identified by Mansfield. The matrix of the fossils is unlike the typical Caloosahatchee formation, which is sandy, but the fauna is closely related to that of the upper part of the Caloosahatchee formation and is regarded as a facies of the Caloosahatchee. The fauna shows considerable resemblance to that of the Imperial formation of California but may not be contemporaneous with it.