The Museum of Yale University contains a small collection of footprints of much interest, which were found in 1873, in the Middle Coal-measures, near Osage, in South-eastern Kansas. A careful re-examination of these footprints has been recently made by the writer, and the main results are given in the present paper.

The impressions are well preserved in a calcareous shale, which separates readily into thin slabs, each representing a surface of the beach at the time the footprints were made upon it. A few shells in the shale are sufficient to prove that the formation is marine. Trails of annelids, and perhaps of other invertebrates, are seen on some of the surfaces.