Many years ago, after a short experience in collecting crinoid cups at the localities herein noted, especially that of Invertiel, it became evident to me that there was considerable variation in the disposition and shape of the anal plates in the cups of Eupachycrinus and in a lesser degree in those of Zeacrinus and other genera. From this I thought it might be possible, in a large number of specimens, to trace the evolutionary stages in the passage of these plates upwards in the cup, and perhaps even their elimination from the limits of the cup. With thoughts such as these in mind, I have in subsequent years laid aside the majority of the cups I have found, and in 1918 (Trans. Geol. Soc. Glasgow, vol. xvi, pt. iii, p. 376) gave a short account of an examination of 200 cups of Eupachycrinus, 45 of Zeacrinus, and 50 of Hydrieonocrinus. This examination was necessarily hurried, owing to the circumstances of the time, but it convinced me that some interesting results would be obtained from a larger series. It was not, however, till recently that I was able to begin this work, my original intention being not only to deal with the cups of the three genera already mentioned but also with a considerable number belonging to Ulocrinus and Woodocrinus. As the sorting and cleaning of the specimens proceeded it became evident that this would occupy considerable time. I have accordingly thought it advisable, in the first instance, to confine attention to Eupachycrinus and Zeacrinus, and in this communication propose only to give the results of the study so far as it has gone.

In 1880 I communicated to the Manchester Geological Society a short paper, on the above subject, which endeavoured to show that Ramsay's suggestion of glacier erosion cannot explain the origin of Rock Basins. I have often since considered the facts and arguments advanced by different writers on the subject, but am more convinced than when I previously wrote that our Lake Basins were not formed by glacier erosion. The arguments herein are additional to those employed in my communication to the Manchester Geological Society.

All of us have read how, in the infancy of modern geology, men were exceeding liberal of theorizing; indeed, it might almost be said that their theorizing, and their confidence in it, were in inverse proportion to their knowledge. Then arose the Geological Society of London, with its appeal for “new facts” and for “investigating the mineral structure of the Earth”, in other words, for application of the inductive method, and for placing geological inductions upon as broad a basis as possible. The result of which we know; the science went forward from that hour.

Some of us are old enough for our geological infancy to have been nourished on books which were written at a time when the “Silurian System” was threatening to annex the whole of the Lower Palaeozoic Rocks. Most of us welcomed Lapworth's arrangement, which now seems to have won general approbation. In the interim, however, the following compromises were proposed:

Neither of them has been widely adopted. It is to be noted that De Lapparent's proposal of “Gotlandian” was made because he had already made use of “Silurian” as an inclusive designation. His selection of the term was of course founded upon the fact that the beds in question are finely developed in Gothland.