green to olive-green color, a waxy lustre, and is quite soft. Found at Leiperville, Delaware County, Pa.; described by G. A. König.

Liskeardite.—A hydrous arsenate of aluminium and iron, related to evansite. It has a white color with a slight bluish tint, and is observed in thin fibrous layers lining hollows in quartz and other minerals. From Liskeard, Cornwall; described by N. S. Maskelyne.

Lithiophilite.-A phosphate of manganese and lithium, analogous in composition to triphylite, which is a phosphate of iron and lithium. It is found in large masses, commonly of a delicate salmon color and a sub-resinous lustre. It has three distinct cleavages, two at right angles to each other, and a third prismatic. Found at Branchville, Fairfield County, Conn., where it is immediately associated with a large amount of a jet-black manganesian phosphate formed from its alteration; described by G. J. Brush and E. S. Dana. Mangantantalite.-A manganesian variety of tantalite (9.5 per cent. MnO) from Utö, Sweden; described by A. E. Nordenskiöld.

Pandermite. A hydrous borate of calcium. It has a snow-white color, and in appearance resembles a fine crystalline marble. Found in rounded masses imbedded in gypsum at Panderma on the Black Sea; described by G. vom Rath.

Penwithite.-A hydrous silicate of manganese. It is a highly vitreous, transparent, reddish-brown mineral, occurring with quartz and rhodochrosite. From the district of Penwith, Cornwall; described by J. H. Collins.

Picroalumogene.-A hydrous sulphate of magnesium and aluminium, differing from pickeringite in its larger percentage of water. It is a white or slightly reddish mineral, forming stalactitic fibrous masses in the iron-mine of Vigneria, Elba; described by G. Roster.

Pseudobrookite.-A mineral similar in composition to menaccanite (titanic iron), but unlike in crystalline form. It is found sparingly in minute thin tabular crystals belonging to the orthorhombic system, and closely resembling brookite in general appearance and habit. The color is dark brown to black, and the lustre metallic adamantine; opaque. From the Aranyer Mountain, Transylvania; described by A. Koch. Pyrophosphorite. - An anhydrous pyrophosphate of cal

cium and magnesium. An opaque, earthy, snow-white mineral, having a hardness equal to 3 and a specific gravity of 2.5. From the West Indies.

Reddingite.-A hydrous phosphate of manganese, related to scorodite in composition, and closely similar in form. It appears in minute orthorhombic octahedrons, of a rose-pink color and a vitreous to sub-resinous lustre. Found rarely with other manganesian phosphates at Branchville, Fairfield County, Conn.; described by G. J. Brush and E. S. Dana.

Rhabdophane.-A phosphate of didymium, erbium, and other metals. It resembles sphalerite, and has formerly passed for that species, but was recognized by the absorption-bands which it gave in the spectrum. From Cornwall, England; described by W. G. Lettsom.

Steelite.-A variety of mordenite, described by How as occurring in the trap at Cape Split, thirteen miles from Cape Blomidon, Nova Scotia.

Stibianite. Supposed to be a hydrated oxide of antimony formed from the decomposition of stibnite. It is a massive, somewhat porous mineral, of a reddish-yellow color. From Victoria, Australia; described by E. Goldsmith.

Stützite.-A telluride of silver, isomorphous with dyscrasite and chalcocite. Found in minute, highly modified crystals upon a specimen of gold from Transylvania; described by Schrauf.

Szaboite.—A silicate of iron and calcium, related to babingtonite. It occurs in small thin crystals belonging to the triclinic system. The color is hair-brown to hyacinth-red, and it is almost opaque. Found in the Aranyer Mountain, Transylvania; described by A. Koch.

Taznite.-A chloroarsenate and chloroantimonate of bismuth found at Tazna, Bolivia; described by J. Domeyko.

Totaigite.-A mineral of uncertain character, related to serpentine, and probably produced by the alteration of pyroxene. From Totaig, Ross-shire, Scotland; described M. F. Heddle.

Triploidite.-A hydrous phosphate of manganese and iron, related to triplite. It is found occasionally in distinct crystals belonging to the monoclinic system, and similar in form to those of wagnerite; more generally it has a fibrous to columnar structure. The color is yellowish to reddish brown, occasionally hyacinth-red; it is transparent, and has a vitre

ous to greasy lustre. Found at Branchville, Fairfield County, Conn.; described by G. J. Brush and E. S. Dana.

Vietinghofite.-A highly ferriferous variety of samarskite, from the neighborhood of Lake Baikal, in the Ural; described by Von Kokscharof.

METEORITES.

In the last volume of the Record, allusion was made to the native iron of Ovifak, Greenland, which was first described by its discoverer, Professor Nordenskiöld, as of meteoric origin. A recent memoir, by Dr. J. Lawrence Smith, published in the Comptes Rendus of the French Academy, is an important contribution to our knowledge of the subject. Dr. Smith expresses himself strongly in favor of the theory of the terrestrial origin of the iron, and mentions a number of arguments which seem to prove this conclusively. One of the most important of these is derived from the microscopic study of the rock in which the masses of iron occur; by which means the iron is discovered to be scattered in minute grains through its mass, and so intimately mixed with the feldspar as to imply a contemporaneous origin.

Dr. Smith also shows that certain other masses of native iron, discovered during the past sixty years at different points on the Greenland coast, and which have been called meteorites, are remarkably similar to the Ovifak iron, and, with that, are probably in fact terrestrial. The occurrence of this native iron may be explained either--as argued by Steenstrup-as due to the reduction of the oxide by the carbonaceous material through which the basalt has been ejected, or else by assuming that the iron itself was thrown up with the basalt from some profound depth.

The locality of the iron described, at Ovifak, near Disco, was visited during the past summer by Captain Tyson and his party, on board the schooner Florence. Both he and Mr. O. T. Sherman, the meteorologist of the Howgate expedition, brought away a number of interesting specimens of the iron, and of the basalt which contains it.

Of true meteorites, several have been described during the past year as those of Grosnaja, of Ställdalen, of Tieschitz, and of Vavilovka. None of them, however, offer any points of peculiar interest.

GEOLOGY.

By T. STERRY HUNT, LL.D., F.R.S.,

PROFESSOR OF GEOLOGY, INSTITUTE OF TECHNOLOGY, BOSTON, Mass.

PRE-CAMBRIAN ROCKS.

The attention of geologists is more and more drawn to the study of the stratified crystalline rocks. So long as these were supposed to be due to the alteration, over certain regions, of sediments of Paleozoic or more recent times, they possessed but a secondary interest; but since we have learned to recognize in them portions of great series of higher antiquity, they assume a new importance to the student, alike from the geognostic and the geogenic side. As regards the former, much progress has been made in their lithology, paleontology, and stratigraphy; while the question of their origin brings up in new forms the old questions of plutonism and neptunism. The microscope is now applied with great success to the study of crystalline rocks, but the opinions of microscopists on many points of lithology are as yet unsettled, and the criteria upon which some have relied to distinguish between eruptive and indigenous rocks are found to be fallacious; while the tendency of the latest results, in the judgment of many, is towards a limitation of plutonism and a wider extension of neptunism.

WALES.

The crystalline rocks of Wales, noticed in the Record of last year as pre-Cambrian, have been further examined with important results. The groups to which Hicks gave the names of Dimetian and Pebidian were first found in a ridge protruding from the Cambrian strata at St. David's, in Pembrokeshire, South Wales, but have since been found in a second parallel ridge about ten miles to the east, on which is situated Castle Roche, and also in North Wales, both in Caernarvonshire and Anglesea; in each one of the four districts presenting the same geognostical and lithological re

lations. The lithological characters of the oldest series, which received the name of Dimetian, were at first somewhat vaguely given. It may be described as consisting essentially of a somewhat granitoid gneiss, generally without mica. What were called quartzites are really very quartzose feldspathic rocks. Interstratified with this series at St. David's are several thin bands of a coarsely crystalline limestone, mixed with quartz and a serpentinic mineral. The exposures of these rocks are comparatively small. Hicks at first included in the Dimetian great masses of what had been by the geological survey of Great Britain described as an intrusive feldspar-porphyry, which, associated with granite (Dimetian), had been injected among the Cambrian strata, locally changing them into the crystalline Pebidian schists. These porphyries, which are found in each one of the four districts, consist of a great series of highly inclined beds of a compact petrosilex or orthofelsite, at times laminated, sometimes concretionary or spherulitic, often including crystals of feldspar and of bipyramidal quartz (as described by Tawney), and undistinguishable from the hälleflinta of Sweden and the feldspar-porphyries so widely displayed in North America (Record for 1876, p. xcvi). These latter were originally regarded, like those in Wales, as eruptive, but were by Hunt declared to belong to a stratified series included by him in the base of the Huronian, and subsequently distinguished by Hitchcock under the name of Lower Huronian. They are absent in many localities in North America, between the Laurentian and the Huronian, with which latter the Pebidian of Wales is apparently identical; and near St. David's, in Pembrokeshire, a conglomerate at the base of the Pebidian includes, in a paste of greenstone or diorite, fragments and pebbles of the banded orthofelsiteporphyries of the vicinity. Elsewhere in that region these rocks are wanting, and the Dimetian granitoid rocks are directly followed by the Pebidian. Hicks, therefore, now refers the feldspar-porphyries to an intermediate series, distinguished by the name of Arvonian, from Arvonia, the ancient Roman name for Caernarvon. The Pebidian rocks of the various areas named are undistinguishable in lithological characters from the Huronian of North America, as seen alike in the Atlantic belt, near the great lakes, and in the region of