A new morphological type of Paleozoic calcareous alga is represented by Calcipatera cottonwoodensis n. gen. and sp., a codiacean species found in the Cottonwood Limestone Member, Lower Permian, of eastern Kansas. The new species, as reconstructed from serial sections of weathered out, in situ, intact specimens, had a broadly obconical, cup-like membranous thallus. The internal structure of the membrane as seen in cross section consisted of a medulla with mosaic sparry calcite and bilateral cortices with calcite packets forming utricular molds similar to those of other known membranous algae. The sparry calcite apparently replaced the lightly calcified or uncalcified intercoenocytic spaces in the medulla and the calcite crystals replaced the interutricular aragonite. The organism had previously been identified as Anchicodium Johnson.