W hen I was in Vienna in the spring of 1879, Franz Ritter von Hauer, the Director of the Imperial Geological Survey, requested me to examine and described the remarkable organism on which Von Meyer had founded the genus Psephophorus , which, although noticed by himself, by Von Meyer, and more recently, by Dr. Fuchs, has never been figured. Its nature was at first sight so problematical that opinion loaned to the conclusion that it was the dermal covering of an Edentate closely allied to the Armadilloes. The dorsal surface of the fossil was perhaps insufficient to settle this question without a good deal of comparative work; but Von Hauer courteously allowed me to partially develop some fragments of bones, which are imperfectly preserved on the underside of the intractable sandstone matrix of the slab; and these fragments of procœlous vertebræ proved to be altogether reptilian; and though differing from the vertebrae of known reptiles, yet, by forward projection of the zygapophyses, they indicate the animal to be Chelonian, and therefore show the fossil to be more nearly allied to Sphargis than to any other type in the Chelonian order. When Von Meyer first gave a name to this genus (‘Jahrbuch,’ 1846, p. 472), it was only known to him by isolated dermal plates ; but subsequently a drawing was sent to him by Partsch, and on that he made a further note in the ‘Jahrbuch’ for 1847 (p. 579). This specimen, then in Pressburg, he describes as a fragment of a