16 ments on heulandite. Anhydrous H,SO, abstracts 2 H2O from the molecule Ca Al, Si,O16+6 H2O leaving Ca Al, Si,O18 + 4 H,O. The latter compound is optically quite different from the original heulandite, having, for example, a much higher double refraction and a dif ferent plane of the optical axes. The change may be watched under a microscope, and takes place faster in some crystallographic directions than in others. Dilute sulphuric or hydrochloric acid gives a pseudomorph, which, after heating, is composed of almost pure SiO, (only 1.33 per cent bases). It has a specific gravity of 2.143, is optically biaxial with a small angle, and has weak double refraction. It is regarded as a new modification of SiO,, probably like Scacchi's "granulin." In continuation of his studies on Algerian minerals, Gentil' mentions with more or less detail calamine, smithsonite, sphalerite, calcite, galena, cerussite, limonite and barite from a number of zinc mines. Ilvaite and bustamite from Cape Boujaroun are also studied somewhat at length.-Dufet publishes the results of a crystallographic study of four modifications of indophenol, also of several complicated organic and inorganic compounds which are not at all related to one another. -Lacroix11 describes the microscopical characters of a number of compact or earthy minerals. They are not amorphous, as they appear to the naked eye, but are all micaceous and crystalline in ultimate structure.-Termier12 reports seven new forms, and a large number of rare ones, on a quartz crystal discovered on a block of gneiss in the lateral moraine of the lower Grindelwald glacier. The new forms are 7.7.0.4 32.15.17.62 11.25.36.0 10.35.25.20 1.4.5.2 17.4.21.9 3.4.7.7 The explanation of these rare faces is sought in the deposition of calcite on the quartz, followed by the formation of " temporary limiting" faces as the crystal again grows, and, finally, the solution of the out Bull. Soc. Fr. Min., XVIII, pp. 399-414, 1895. 10 Bull. Soc. Fr. Min., XVIII, pp. 414-426, 1895. 11 Bull. Soc. Fr. Min., XVIII, pp. 426-430, 1895. 12 Bull. Soc. Fr. Min., XVIII, pp. 443-457, 1895. side of the quartz, thus exposing again the unusual faces. Some of the calcite layers are still present in the specimen. 4 The new mineral lawsonite is more fully described by Ransome and Palache13 than was the case in the original paper by Ransome. The formula is H, Ca Al, Si,O10.-Walker" finds that the sperrylite from the Sudbury district probably occurs originally included in chalcopyrite. The new face (10.5.2) was observed. The suggestion is made that Os and Ir occur replacing Pt in sperrylite, and an analysis of the products of the Murray mine, showing the presence of these elements, is given. (If, as this analysis would indicate, the two elements osmium and iridium are present in an amount equal to one quarter that of the platinum, it is difficult to suppose that they exist in the sperrylite, since Wells states specifically that he found no iridium in the sperrylite analyzed by him).-Adams and Harrington's describe a new alkali-hornblende chemically near an orthosilicate, and a titaniferous andradite from the nepheline-syenite from Dungannon, Hastings Co., Ontario.—Merrill notes an occurrence of free gold in a black mica granite from Sonora, Mexico, apparently as an original constituent of the rock.-Crocoite crystals from Mt. Dundas, on the west coast of Tasmania, measured and figured by Palache" present, in addition to the twelve known forms the new, though doubtful, prism (10.3.0). GEOLOGY AND PALEONTOLOGY. Permian Land Vertebrata with Carapaces.-In the NATURALIST for 1895 (November) I described under the name of Dissorhophus a new genus of probably Ganocephalous Stegocephalia with an armadillo-like carapace. In the Proceedings of the American Philosoical Society for the same year and month I described a new family of Cotylosaurian Reptiles protected by a similar structure. These constitute the only forms of land vertebrates so constructed known from the paleozoic formations. The nearest approach to it previously known from the Permian is seen in the genus Zatrachys, where the 13 Zeitschr. f. Kryst., XXV, pp. 531-537, 1895. |