We are indebted to the Trustees of the Carnegie Trust for the Universities of Scotland for a grant to cover the cost of the plates in illustration of this paper. We are also grateful to Mr. S. Fingland for the care taken in preparation of the photographs.

The three principal ophiolithic groups of this region are those of Levanto, Monte Bianco, and Monte Penna, about midway between Spezia and Genoa, viz. north of Levanto, Sestri Levante, and Chiavari, at average altitudes of 300, 800, and 1,600 metres respectively. Like the Eocene ophiolithic group of Sestri Ponente and Isoverde, west of Genoa, they lie in the upper horizon of that formation, that is, in the fossiliferous (fucoids) albarese limestones and the argillaceous schists which rest on the Middle Eocene macigno sandstone as the lowest member of the Ligurian Eocene. The sedimentary and infolded ophiolithic groups consecutively aligned from the coast to the crest of the Apennines form a series of anticlines north to south, dipping west, with some transverse folds. The whole region is greatly contorted and brecciated; it is, moreover, profoundly eroded by torrents charged with calcium carbonate which has accelerated erosion and at the same time re-cemented breccia. Although the three groups are now separated, they are, together with the scattered islands north of the crest of the Apennines towards Piacenza in the Po Valley, only the remnants of an originally continuous formation of no less than 1,500 square kilometres or 600 square miles.

The observations presented by Mr. J. Wilfrid Jackson (1916) on my paper on “Brachiopod Morphology”, published in this Magazine in 1915, are very welcome as furnishing many important details omitted by Davidson and other writers in the description of species. The error into which I fell as regards the types of folding of Dallina and Dalinella illustrates the danger of relying on figures when specimens are not available, but it was worth while making such an error when the correction of it brought forward so many useful observations on other points, particularly on the prevalence of dental plates in the Dallininæ and the relationships of Mühlfeldtia. These observations pave the way for a further advance in the natural or genetic grouping of species and genera. At the same time, while admitting that Dallina is ventrally biplicate, I am not disposed to agree with Mr. Jackson that the folding is exactly comparable to the ventral biplication exhibited in some species of Magellania, but probably arose in a different way. I refrain from a further statement on this point, as I understand that Mr. S. S. Buckman is discussing the subject of types of folding fully in his forthcoming memoir on the Jurassic Brachiopods of Burma. In what follows I shall have again, through lack of specimens in Colonial museums, to rely on figures to some extent, and may possibly again err from this cause, and if so hope the correction will be applied as promptly and informatively as in the former case.

Dr. preller's recent contributions to this Magazine on the geology of the Piedmontese Alps prove that (1) Italian authorities have expressed widely different opinions on this subject, and (2) some of them have maintained sundry Alpine gneisses and crystalline schists to be Palæozoic or Mesozoic (often Permian or Trias) in age. I infer from these contributions that he is well acquainted with the physical geography of this region, but fail to find in them any signs of either microscopic study or independent petrological work. As these have led me in several cases to very different results, I shall venture to put them on record as briefly as possible. In the course of thirty-five visits I have wandered over the peaks and valleys of the Alps from the southern border of the Cottians to the Salzkammergut, paying at first much more attention to physical than petrological questions. But in 1869, when beginning to lecture on geology, I found not only (as I was already aware) that my knowledge of rocks was scanty, but also that on this subject very little trust could be given to much that had been written. So I tried, as best I could, to teach myself. With this intention I visited many places of petrological interest in our own country and on the Continent, forming (partly by purchase) a considerable collection of rock specimens and slices. Circumstances soon directed my attention to the gneisses and crystalline schists, and from 1872 I paid more and more attention to them in my Alpine journeys, of which this was the thirteenth. In 1885 (my twenty-first journey) I began endeavouring to obtain clearer ideas about their succession, history, and relation to the ordinary stratified rocks, by running sections, sometimes up to, sometimes across the watershed of the chain, going in that year from the Lake of Lucerne to the Lago Maggiore and returning across the Great St. Bernard.

Errata and Addendum to Mr. Leonard Hawkes's abstract of paper read at British Association (see Geol. Mag. for October): p. 468, 1. 10, for Borganfjord read Borgarfjord; 1. 11, for Bernfjord read Berufjord; p. 469, 1. 8, for ice-scratched boulder read ice-scratched liparite boulder.

Errata in Mr. P. G. H. Boswell's abstract, October, pp. 466–7: §1,1. 5, for rise above 0.5 per cent read rise above 0.02 per cent, and (two lines lower) for 0.02 per cent read 0.5 per cent. § 3 : the opening paragraph should read: “as simple as possible ; the sand ought to contain only quartz.” In the next paragraph the fourth sentence should read : “The important supplies of glasssands occurring in Western Europe are all associated with planty material, Lippe sand occurring with rafts of braunkohle.” For the locality Hohenboka read Hohenbocka, and for Berrythorpe read Burythorpe.