The following notes were prepared at the request of Dr. J. E. Stead, F.R.S., the well-known metallographer. Several years ago he had obtained in a tin-antimony-arsenic alloy some remarkable crystals having the form of seganents of spherical shells (fig. 3, p. 9.72 below), and he naturally wished to learn if anything of the same kind was known amongst minerals. The notes contain no new data, but merely collect together facts already known to mineralogists. They may perhaps be of some use to metallographers in calling attention to the various habits of growth met with amongst minerals, since distortions and irregularities of crystalline growth are so frequent amongst metals.

While investigating the relies of early habitations at Beraeis, near Jebel Katul, 100 miles N.W. of El Obeid, northern Kordofan, Dr. C. G. Seligman found a number of implements all made of a finegrained, blue-grey stone, quantities of which he found at the base of Jebel Katul. A fragment of this stone was examined by Dr. G. T. Prior in 1912, and found to be rich in riebeckite.

Early in 1914 a parcel of copper-nickel-cobalt ore, weighing several tons, was received in London for valuation from the 'Cármenes mine, Spain'. This somewhat vague statement of locality refers without doubt to the group of mines in the district of Cármenes, province of León, situated about 6 km. E.N.E. of Viilamanín, a statisn on the railway from Gijon to León and about 40 km. N. of the latter city. The ores of these mines are described as consisting of sulphide minerals of copper, cobalt, and nickel in a gangue of dolomite.

It is the author's good fortune to collaborate with Dr. J. W. Evans in describing the rock specimens which he collected on the expedition to Caupoliean in Bolivia during 1901-2. These specimens contain a very large proportion of shales, slates, and phyllites, and in their investigation certain petrographic methods devised for a detailed study of the slates of North Wales, Devon, and Skiddaw were followed. The present paper is intended primarily to describe these methods as applied particularly r the Bolivian rocks and to a Skiddaw slate facies which, for purposes of comparison and contrast, is of special interest. It is not suggested that between groups of rocks from places so widely separated as Bolivia and Skiddaw close correlation is possible; the products of the reconstitution processes which the two groups record differ considerably in detail; but as providing data for the study of the mechanism of these processes the two groups can be conveniently examined together.

James Sowerby in his ‘British Mineralogy’ describes and figures sider the head of ‘Argilla electrica’ or ‘White Tourmaline’ a mineral which was undoubtedly phenacite. The specimen was sent to Sowerb,y by a Mr. Herbert in 1804, and was said to have been found in a mine in St. Just, Cornwall. According to Sowerby's description and from the eoloured plate which he gives of the specimen, the mineral occurred as long-prismatlc, colourless crystals , some of which were doubly terminated and lying upon and partly penetrated by mass of prismatic quartz crystals. The crystals were ‘so divided by cracks and flaws in general as to appear of an opaque whiteness in parts’.