Article: A new calamitalean cone from the Middle Pennsylvanian of southern Illinois
F. A. Hibbert and D. A. Eggert
A new species of the calamitalean cone genus Paracalamostachys Weiss, P. cartervillei, is described. The holotype consists of a group of cones found in an 'ironstone' nodule of Middle Pennsylvanian age. The cones are small, ranging from 11 to 17 mm. in length, and 4-0 to 4-5 mm. in diameter. Several cones are present at a node on the cone-bearing stem, they lack peduncles, and consist of whorls of bracts and sporangiophores arranged alternately, the fertile whorls being superposed. Approximately six sporangiophores are present in the fertile whorl and twelve bracts in the sterile whorl. Each sporangiophore bears four horizontally elongate sporangia arranged in the form of a Maltese cross around a central stalk. The sporangiophores are enclosed by the upturned ends of the subtending bracts. Spores ranging in size from 40 to 100 µ were isolated from sporangia and are referable to the form genus Calamospora Schopf, Wilson, and Bentall, being comparable to the dispersed spore species, C. breviradiata Kosanke. The cone is apparently homosporous and is compared with previously described species of the genus Paracalamostachys Weiss and related genera.