During the War a considerable amount of work of a somewhat geological nature was done in the laboratories of Nobel's Explosives Co., chiefly in connexion with providing acid-resisting material for use in the sulphuric and nitric acid plants.

Last year, I published a theory of the structure of the South-West Highlands in which was included a short statement regarding the metamorphism of the district (1922, p. 92). It seems that movement and metamorphism in this particular region have been too closely contemporaneous to allow of a tectonist deriving much assistance, in the initial stages of his work, from a study of the metamorphic condition of the various rocks with which he has to deal. There is no suggestion anywhere of contrasted metamorphisms having been brought into contact as a result of thrusting. If, as I suppose, there have been great thrust-movements, these must, for the most part, have occurred before the conclusion of the metamorphic period.

In the Geological Survey Memoir, “The Geology of the Coasts adjoining Rhyl, Abergele, and Colwyn,” Mr. (now Sir Aubrey) Strahan most truly observes (p. 18): “There is in scarcely any part of this country a more remarkable development of chert than that which overlies the Carboniferous Limestone of North Flintshire.”

Speculation as to the causes of the great intrusions known as batholiths is coeval with petrology as a science. Daly says that batholiths are “the least understood of all the intrusive bodies. If they were truly understood there would be no ‘problem’ of the igneous rocks”.1 This, no doubt, puts the matter too strongly, but there is nevertheless much truth in the statement, and the “problem” is of the greatest importance in petrogenic theory.

Recently I had an opportunity of paying a brief visit to the localities described by Miss Elles as affording a clue to the horizon of the Hirnant Beds. As I have for many years believed that the fauna of the Hirnant Beds is Ordovician, I was anxious to see upon what evidence the assignment of those beds to the Silurian was based. The Bwlch-y-groes locality was visited with Professor W. J. Pugh, University College of Wales, Aberystwyth, who will shortly deal with the structure of that area. It is sufficient for the present to state that this section has been misinterpreted by Miss Elles, and so far from proving that the Hirnant Beds lie within the Valentian, shows, if anything, that they cannot possibly form part of that series, which is fully represented there and has much the same characters as throughout Central Wales. To anyone thoroughly familiar with the Ordovician-Silurian succession of Central Wales, the structure and rock-succession of the Bwlch-y-groes Pass presents no difficulty and it certainly gives no support to the idea that the Hirnant Beds are of Lower Valentian age.

Since the establishment of the two genera Tentaculites and Cornulites by Schlotheim in 1820 their relations have frequently been discussed, but no general agreement has been reached, and their characters have been differently defined by various authors, so that the generic position even of well-known species is rather an open question. For instance, the proper reference of “Tentaculites” anglicus Salter is still somewhat undecided.