The creature which forms the subject of the present communication is the same as that which was described as Asterolepis by Hugh Miller in his “Footprints of the Creator,” and consequently its remains are at present better known to British geologists and palæontologists under that name. Why, then, alter a name which we have used so long? is a question likely to be asked by those who have not critically studied the complicated mesh in which the synonymy of the name “Asterolepis” is entangled.

Until quite lately no fossils had been found in the Lower Cambrian of Bethesda. Indeed we had almost given up the hope of obtaining any evidence of the life of the period represented by them, because of the great alteration in the character of the rock resulting from the severe mechanical action to which it had been subjected. The announcement that Mr. Robert Lloyd had discovered fossils in the uppermost slate beds of the Penrhyn Quarries was therefore received with great interest, which was increased when it was found that some of these were in a sufficiently perfect state for determination, and that they were referred by Dr. Woodward to a new species of a well-known Lower Cambrian genus of Trilobite.

The problem of the metamorphism of rock-masses is one in which increased study has not led to unanimity of opinion. The literature of the recent Geological Congress in London suffices to remind us, how widely divergent are the conclusions to which various geologists have been led by researches in the field. Since, then, the a posteriori line gives such very different results in different hands, it may be worth while to revert for a moment to the deductive method, and try to trace the consequences, in this connexion, of admitted physical principles.

On the extreme north-west flank of the Lower Palæozoic region of the Southern Uplands of Scotland there occurs a remarkable coastal area of stratified, igneous and altered rocks, known to geologists as the “Ballantrae Rocks,” from the little fishing town of Ballantrae, which is built upon them. They range along the shores of the Firth of Clyde for a distance of about 12 miles, and are well displayed in section in a series of rugged cliffs cut through by the picturesque coast road between Ballantrae and Girvan. The area they occupy nowhere exceeds five miles in width, and is limited inland by the smoother regions floored by the barren greywackés of the Uplands and the fossiliferous strata of the Girvan district, but this inland boundary is everywhere curiously broken and irregular.

So little is as yet known of the Palæozoic Ophiuroidea, that the discovery of some specimens that represent a new species of Protaster in the Upper Silurian rocks of Victoria is of interest. Some of the specimens were forwarded to Dr. Woodward by Mr. Frederick McKnight, of 60, Hawke Street, West, Melbourne, Victoria, some time ago, but they were too fragmentary to be of much service; several better examples having been received from the same source, Dr. Woodward has kindly entrusted them to me for description.

Some years ago, in showing that the spines supposed by Hancock and Atthey to be dorsal spines of Gyracanthus were merely young and unworn specimens of lateral spines of the same genus, I called attention to the general fact that young examples of Selachian spines could not be expected to represent the older ones in miniature, and vice versa.