In the year 1860, when engaged in drawing up a list of the fossils known to occur in the Lower Old Red Sandstone of Scotland, we had occasion to remark that, with the exception of the Pteraspis, we had found in our northern rocks the various fossils of the equivalent beds in England, and many others besides, indicating an extensive piscine fauna in that epoch of geological history. We have now to remove that exception, for Pteraspis does occur with us. Some very fine specimens have recently been found in our Scottish rocks, and from their examination we are not only able to discern that fragments which have been many years in our possession, and which we could not refer to any known fossil, belong to that palæozoic fish, but we are also encouraged to attempt the restoration of the remarkable buckler, composed of solid bone, in which this ancient denizen of the deep was encased.

Figure 1. In the construction of this diagram three fossil specimens have been employed. These specimens are similar in their proportions and in the method of their preservation, and their exact measurements have been followed in the figure. The first specimen, used for this diagram, exhibits very beautifully the form of the shield with the terminal horns, and the distinct eye-sockets. The eyes are placed on the margin of the shield, and their impression is also seen on a cast in the stone of this specimen. The second specimen is the prolonged central termination of the shield, which has been broken off at the ridge which terminates on either side in the horns. The third specimen show’s the junction of this central prolongation with the shield. All the three specimens have a high central ridge, and still retain something of the graceful outline of the living form. As preserved in the stone these specimens show only the nacreous layer, the other component layers of the bone of the Pteraspis having perished in their case.