It is a well-known and undisputed fact that the Carboniferous succession of the Midlands differs very considerably from that which obtains in North Yorkshire, Northumberland, and Scotland, and the correlation of the Carboniferous sequence in various parts of Great Britain and Ireland has been a matter of difficulty and dispute. A study of the literature of the subject, voluminous and scattered though it be, seems to show one important fact, and that is that very few, if any, of the writers had studied the succession in more than one or two localities, or had given any attention to the evidence afforded by paleontology. To Yorkshire geologists, the sequence of the Carboniferous rocks in their county should be of the highest interest, not only on account of the large number of sections exposed in the romantic dales, for which the county is so justly famous, but because the change from the northern to the southern type of stratigraphical succession takes place in the county, and because, I am convinced, an accurate knowledge of the geology and paleontology of the Carboniferous rocks of the West and North Ridings will go far to settle the whole of the vexed question of correlation. During the last five years I have published a series of papers on the correlation and sequence of the Carboniferous rocks of the Pennine axis and the south of Scotland, in which the following theses have been developed:— ( a ) That the differences in the northern and southern types of the Carboniferous ...