Last Autumn, on our way to St. Cassian and the Dolomites, we remained for two or three days in the Eifel. The little town of Gerolstein is well known to all geologists. Mr. Winter, one of the inhabitants, who pays considerable attention to the natural history of the place, was kind enough to present me with a nodule which, though apparently it is very insignificant, yet, on further examination, seems of great interest; it contains, in fact, part of the scale of a Pteraspidean. Any one who has worked amongst the Old Red Sandstone fishes of Monmouthshire and Herefordshire will at once recognize many of the characteristics of the Pteraspidean scales.