[Footnote 25: _Geological Observer_ (1851), pp. 642-645.] [Footnote 26: _Student's Manual of Geology_, 2nd edit. (1863), p. 523. For a general _résumé_ of the proofs of contemporaneity furnished by the toadstones, see "The Geology of North Derbyshire," by Messrs. A. H. Green and A. Strahan (_Memoirs of the Geological Survey_, 2nd edit. (1887), p. 123).] [Footnote 27: In the first edition of the _Memoir on the Geology of North Derbyshire_, published in 1859, the authors of which were Messrs. A. H. Green, C. le Neve Foster and J. R. Dakyns.] The subject, however, has now been resumed by Mr. H. Arnold Bemrose, who in 1894, after a prolonged study of the petrography of the rocks, communicated the results of his researches to the Geological Society.[28] In his excellent paper, to which I shall immediately make fuller reference, he mentions the localities at which lava-form and fragmental rocks may be observed, but does not enter on the discussion of the geological structure of the region or of the history of the volcanic eruptions. Before the announcement of his paper, hearing that I proposed to make for the first time a rapid traverse of the toadstone district, for the purpose of acquainting myself with the rocks on the ground, he kindly offered to conduct me over it. My chief object, besides that of seeing the general nature of the volcanic phenomena of the region, was to examine more particularly the areas of the volcanic fragmental rocks, with the view of discovering whether among them some remains might not be found of the actual vents of discharge. In this search I was entirely successful. Aided by Mr. Bemrose's intimate knowledge of the ground, I was enabled to visit in rapid succession those tracts which seemed most likely to furnish the required evidence, and in a few days was fortunate enough to obtain proofs of six or seven distinct vents, ranging from the extreme northern to the furthest southern boundary of the volcanic district. Mr. Bemrose has undertaken to continue the investigation, and will, I trust, work out the detailed stratigraphy of the Carboniferous Limestone so as eventually to furnish an exhaustive narrative of the whole volcanic history of Derbyshire. Meanwhile no adequate account of the area can be given. But I will here state all the essential facts which up to the present time have been ascertained. [Footnote 28: _Quart. Journ. Geol. Soc._ vol. l. (1894), p. 603.]