Redescription and designation of a neotype for Caecum floridanum (Littorinimorpha, Truncatelloidea, Caecidae) with a characterization of the protoconch and growth stages.

After an extensive search for the type specimens of Caecum floridanum Stimpson, 1851, we believe that these specimens may have been either lost or destroyed in the Chicago fire (1871). This paper presents a redescription of the species and a neotype is designated based on material from the type locality (Florida). Protoconch and growth stages of Caecum floridanum are described and illustrated herein. The teleoconch IV of Caecum floridanum is characterized by strong, wide, low, rounded, closely arranged axial ribs, except last three to four preceding the aperture, which are larger and more widely separated. Caecum compactum Dall, 1892 is here synonymized under Caecum floridanum. Caecum annulatum Emmons, 1858 and Caecum dux Folin, 1871 are not considered synonyms of Caecum floridanum in this report.