The skeleton of Pareiasaurus Baini, which I brought from the Bath near Tamboer Fontein, in Cape Colony, is shown in the accompanying photograph of the right side of the specimen, as it is now mounted in the British Museum. It is the only known example of the group of animals to which it belongs, in which almost every part of the skeleton is shown. The Dicynodonts were familiar to us from the discovery of many skulls; the Theriodonts were mostly known from snouts; and the Pareiasaurus, although originally described from skull remains, had become known from the fine axial skeleton of P. bombideus, which Mr. Thomas Bain sent to the British Museum many years ago. I therefore entertained hope that the limbs and other missing parts of the skeleton might reward personal exploration in the country. The area to be examined was clearly defined as lying approximately between the Prince Albert Road Station and Fraserberg; for Dr. W. G. Atherstone had found the type of the species near the former locality, and Mr. Bain had found the specimen described by myself in 1887–8 at Palmiet Fontein, at the foot of the Nieuwveldt Range, towards the latter place.

While the favourable reception which the Astronomical Theory of the Ice Age has met with among scientific men has been chiefly due to the writings of Dr. Croll, its more general acceptance, especially among the semi-scientific public, has been greatly assisted by the lucid and vigorous exposition by Sir Robert Ball, in his “Cause of an Ice Age,” published in 1891. But notwithstanding the apparently exhaustive way in which Croll discusses the problem, and the fact that Sir Robert Ball's work has been published in the “Modern Science” Series (indicating that the theory has secured a place among the permanent acquisitions of science), I venture to think that a careful examination of the problem will show that the theory is but a vague speculation; clothed, indeed, with a delusive semblance of severe numerical accuracy, but having no foundation in physical fact, and built up of parts which do not dovetail one into the other. The following pages contain what I hope will be admitted to be a justification of this sweeping condemnation. The first portion of my paper deals with Croll's form of the theory; the second, to be published next month, deals with Sir Robert Ball's form.

Dinas Head is a promontory 4 miles west of Padstow, jutting out into the sea from Trevose Head, and separated from it by an isthmus about 100 feet above sea-level, which is washed clear of soil by the ground seas which sweep over it from the north. The headland is 165 feet above sea-level at its highest point, and is almost as broad from north to south as it is long from east to west. The base and foreshore of the headland appear to be entirely composed of greenstone containing much calcite. The microscope shows it to be probably an altered dolerite.

The specimens here referred to belong to the Geological Survey of Canada, having been collected—I. some (of Quaternary age) by Mr. J. B. Tyrrell, B.Sc., F.G.S., in 1887, on the Rolling River two miles above Heart Hill in Manitoba.