Danbury stands on a gravel-capped plateau in Mid-Essex, five miles east of Chelmsford. The gravel is part of a once largersheet and contains a variety of rocks foreign to the district. It was therefore naturally at first regarded as a glacial gravel. This view was adopted by S. V. Wood, jun. (e.g. 1867, p. 12; 1870, p. 61), by the Rev. O. Fisher (1868, p. 98), on the Geological Survey Map (Sheet 1, N.E., 1871), and by Mr. Whitaker (1889, p. 279). Sir Joseph Prestwich regarded the Danbury gravels (1890, p. 135) as Bagshot pebble-beds invaded by some glacial agent, and the late H. B. Woodward (1903, p. 15) described them as the wreck in Glacial times of an older gravel.

Nevadia is the earliest and the most primitive member of theMesonacidæ, and as shown by Walcott may be regarded as representing the ancestral type of this family. The same authorityshows that the Paradoxidæ have descended from the Mesonacidæ. Redlichia also exhibits features which link it with the Paradoxidæ and the Mesonacidæ.

Charnwood Forest, since 1891, the date of the last paper by Canon E. Hill and myself, has been investigated by the Geological Survey. Though part of their map and the accompanying memoir have not yet been published, the general results of their work have been announced by Professor W. W. Watts, by whom most of it was executed. As we stated at the time, we were far from being satisfied with some important points in our own conclusions; so that since my return to Cambridge I have studied my specimens and slices from the north-western region, which had presented to us the more serious difficulties. In 1891 I had been led to regard the characteristic rocks of Peldar Tor and High Sharpley as lava-flows, but considered the dominant rocks of Bardon Hill to be mainly pyroclastic. Professor Watts, however, maintained the intrusive character of the first and second, while taking the same view as myself about the third. The lava-flow hypothesis had appeared to me the more probable, because I doubted whether a mass so large as the Peldar-Bardon porphyroid, if intrusive, could have maintained throughout a texture so uniformly fine-grained, and I had found in the Bardon quarries fragments of it embedded in rock which I then supposed to be a somewhat altered tuff, closely related to the High Sharpley lava.

The range of the Apuan Alps, commonly called the Carrara Mountains, is an offshoot of the Apennines, trending N.N.W. to S.S.E., parallel to the Mediterranean littoral, from which it rises within a distance of barely four miles to a maximum height of 6,000 feet above sea-level. Exclusive of the outer belt of the more recent strata, the Triassic formation, within which the saccharoidal marble beds are situated, covers about 25 by 13 kilometres or about 130 square miles, of which the marble zone proper represents 64 square miles or about half. The range is bounded on the north by the Aullela valley in the Lunigiana district; on the east by the Serchio valley in the Garfagnana district; and on the south by the Serchio valley in the Province of Lucca. The marble district, whose western part faces the Mediterranean, comprises the three divisions of Carrara, Massa, and the Versilia in the corresponding parallel valleys of the Carrione, Frigido, and Serravezza Rivers. The Versilia division, which forms part of the Province of Lucca, is composed of the Seravezza, Stazzema, and Arni subdivisions, of which the last-named lies on the eastern watershed of the Apuan range. The Versilia division also includes Pietrasanta, Camajore, Massarosa, and the wellknown watering-place of Viareggio, near the last-named of which are situated extensive subaqueous deposits of a peculiarly coarse-grained, sharp macigno sand. These deposits, formed as a delta in a lacustrine expanse by the River Serchio, constitute an important and indispensable adjunct of the marble industry as grinding material for the numerous marble saw-mills in the three parallel valleys already referred to.