Comparison of cuticular ultrastructure in Antarctidromia inflata Förster, 1985 from the Miocene Cape Melville Formation on King George Island, Antarctica, with that of the confamilial, extant Homolodromia paradoxa A. Milne Edwards, 1880 suggests that the more rigid carapace of the fossil form results from a relatively thicker, more strongly calcified exocuticle. Epicuticle, exocuticle, and endocuticle are all recognizable on the fossils; however, adherence of the epicuticle to the counterpart may result in misinterpretation of the fine sculpture on the carapace. Absence of dissolution features in the endocuticle confirm conclusions, based upon completeness of remains, that the specimens of Antarctidromia inflata represent corpses, not molts.