The Archipolypoda of the Mazon creek nodules have stout forked spines and two pairs of legs to each segment. Palæocampa may therefore be considered as a precursor of the Chilopoda, just as the Archipolypoda are the precursors of the Diplopoda, and the discovery of these types prove that at this early period the divergencies of structure among myriapods were as great as they are to-day.In the same journal Messrs. McGee and Call write upon the Loess of Des Moines, Iowa, giving faunal tables of the fossils, which have a less aquatic facies than the modern mollusca of the same district.- Messrs. Scott and Osborn describe Orthocynodon, an ancestor of the Rhinoceros, from the Bridger Beds of Wyoming. It is the oldest known representative of the line, and differs from Amynodon in the erect lower canines, similarity of premolars and molars and other particulars. He has little of the rhinocerotic character in the skull, but the possession of canines and loss of the median incisors point it out as related to Amynodon. MINERALOGY.' THE ACTION OF Heat upon Crystals of Boracite.—Mallard contributes to the Mineralogical Society of France an interesting paper upon the change which heat produces in the optical properties of boracite. The leading mineralogists of Germany-Klein, Zirkel, Groth, etc., hold that such changes are due simply to unequal internal tension, such as may be produced in glass. That the biaxial character caused by heat is an essential and characteristic character of boracite, due to the twinning of twelve rhombic crystals around a point, is again strongly urged by Mallard in the present paper. He supposes each individual of the pseudo-symmetrical crystal to be a pyramid whose base forms a face of the external dodecahedron, and whose summit is at the center of the crystal. By cutting sections in various directions through the crystal, and examining them optically both before and after heating, he shows that there are persistent optical properties which cannot be explained by irregular tension. He concludes that by the action of an intense and prolonged heat, a series of very thin plates are formed, alternately twinned with each other according to a definite crystallographic law. He shows that analogous phenomena may be produced by the action of heat upon sulphate of potash, and that such invariable phenomena could not be produced by tension or pressure in a colloid substance. PREHNITE. This zeolite, so frequent in rocks of igneous origin, and recently found to so frequently exhibit curious optical properties, has been carefully described by Professor B. K. Emerson in its associations and alterations in the Deerfield Dike of Connecticut. Prehnite is regarded as the oldest mineral in the veins in which it appears. Frequently the motion of the rock. walls produces slickensides upon the prehnite, and sometimes 1 Edited by Professor H. CARVILL LEWIS, Academy or Natural Sciences, Philadelphia, to whom communications, papers for review, etc., should be sent. breaks it up into sheets, which are re-cemented by prehnite. The prehnite often encloses diabantite, and then varies in color from deep oil-green to jet-black. This black prehnite is sometimes combed out by the slipping rock into long fibres, resembling hornblende or chrysotile. The prehnite also occurs as a finely crystallized double cone or spindle, forming beautiful specimens. This peculiar form is the result of the twinning of three individuals around a common axis, and the resulting optical properties are peculiar. Prehnite also occurs in amydaloidal cavities which are blackened as though held in the flame of a candle. A black substance covers the fibres of prehnite, looking like a net-work of soot-covered cobwebs. This black substance is the result of alteration, and is probably chlorophæite. In other cases the prehnite has changed into a pale-green scaly mass, which appears to be diabantite. AMERICAN MONAZITES.-In the American Journal of Science for October, Professor E. S. Dana and Mr. S. L. Penfield contribute valuable articles upon American monazites. From a careful measurement of a small monazite crystal from Alexander county, North Carolina, by Professor E S. Dana, the following axial ratio was obtained: c (vert): b : a = 0.95484 : I.o3163 : I A table is given containing a list of the more important angles calculated from these data, and agreeing closely with the results of goniometrical measurement. The axial ratio is closely related to that of monazites from other localities. Mr. Penfield has analyzed the monazites from Portland, Ct., from Burke county, N. C., and from Amelia county, Va. The latter is the substance originally thought to be an altered microlite. Each analysis showed a considerable percentage of thoria, there being over fourteen per cent. in the monazite from Amelia county, Va. In each case, if the thoria is omitted from the analysis, the ratio is obtained of (Ce, La, Di), O, : P2 0,= 1 : 1, this being the ratio of a normal phosphate of the cerium metals, R2 P2 Og. Moreover, there is just sufficient silica in each analysis to make a thorium silicate. Since, therefore, some monazites contain no thoria, and the thoria is here present in varying amount, it is probable that thorium silicate exists as an impurity. That this is indeed the case was proved by examination of a thin section of the mineral under the microscope. A dark resinous substance was seen scattered through the section, and when the latter was moistened with hydrochloric acid, white blotches, composed of gelatinous silica took the place of the resinous spots, the rest of the section being unchanged. It is evident, therefore, that the thorium silicate is a foreign admixture in the monazite. It probably exists as thorite or orangite. MINERALS FROM PIKE'S PEAK.-Pike's Peak has already become famous for the number and beauty of the mineral species in its vicinity. Besides the extraordinary specimens of amazon-stone (microcline) from that locality, there have been found smoky quartz, albite, fluorite, biotite, siderophyllite, columbite, gothite, arfvedsonite, astrophyllite, zircon, limonite pseudomorphs, etc. Most of these occur in cavities in granite. Recently Messrs. W. Cross and W. F. Hillebrand have added several species, new to this locality. Several crystals of colorless or pale greenish topaz were found, one specimen being a fragment, which must have belonged to a crystal a foot in diameter. Two imperfect crystals of phenacite were found, this being the first locality known in the United States. Cryolite, thomsenolite and several undetermined species were also found. MINERALOGICAL NOTES.-The volcanic ash ejected from Vesuvius during the eruption of February 25, 1882, has been analyzed by Ricciardi. The ash was black and magnetic. When heated, it gave off hydrochloric acid. It contained particles of magnetite and awgite, and numerous crystals of leucite. As shown by analysis, it also contained a small percentage of apatite. Sulphate and chloride of ammonium were also present, and could be dissolved out by water. Mountain cork has been recently used in Germany as a substitute for animal charcoal for the removal of color from molasses. The mountain cork, a variety of amphibole, is dried, ignited and soaked in molasses, then again dried and ignited. This process is repeated several times until some 3.5 per cent. of carbon has become fixed in the mineral, which is then ready for use. It is more efficient than charcoal in removing the alkalies from molasses. GEOGRAPHY AND TRAVELS.1 DE BRAZZA'S EXPLORATIONS ON THE OGOWE AND THE CONGO.At a recent meeting of the Geographical Society of Paris, M. Savorgnan de Brazza described his recent journeys in the territory between the Ogowé and Congo Rivers, of which, previously, few details had been known. He was directed by the French Government to trace the Alima River, discovered by him on his first expedition (1875-8), to its junction with the Congo and to establish stations on the Ogowé and the Congo. M. de Brazza left France in December, 1879, ascended the Ogowé, and succeeded in negotiating with the tribes on its banks and establishing a regular system of transport on the river. He founded his first station, Franceville, at the confluence of the Passa with the Ogowé. From here in June, 1880, he dispatched 770 natives in 44 canoes to meet his coadjutor, Dr. Ballay, at the coast, and then started alone, with a small party of natives, for the Congo. 1 Edited by ELLIS H. YARNALL, Philadelphia. Two or three days journey from Franceville, the nature of the country changes. To the clayey soil of the Ogowé basin and its richly wooded and moist valleys succeeds a sandy, arid, and hilly country, with here and there, in the neighbourhood of a viliage, a group of palm trees. This is the aspect of the country which forms the water shed between the Ogowé and the tributaries of the Upper Congo; and it is a singular fact that these narrow sandy tracts of country, along the water's bed, are everywhere inhabited by one and the same tribe, the Batcké, reputed, probably erroneously, to be cannibals. When he had passed the Leketi, a southern branch of the Alima, his route lay across the plateau of the Achicuya, an elevated district lying about 2600 feet above the sea-level, and separated from another similar plateau (the Aboma) by the River Mpama. The chief of the Achicuya received M. de Brazza in a friendly manner, and a simlar reception awaited him on reaching the Aboma tribe. These latter are a fine race of people, handsomer and braver than any he had yet met with. It was here that M de Brazza first received definite information regarding the Congo and the powerful chief Makoko, whose sovereignty the Aboma acknowledge. Leaving their district, the party next travelled along the Lefini River-the Lawson of Mr. Stanley. M. de Brazza had just finished constructing a raft for the navigation of the stream, when a messenger from King Makoko arrived with offers of friendship. This much facilitated his further proceedings. He descended the Lefini with the envoy as far as Nyampo, leaving there the raft and journeying by land for two days across an uninhabited table-land. His march over a sun-scorched plateau was most wearisome, and he was beginning to find fault with his guide, when at II o'clock at night, after a forced march, he came in sight of the Congo. It appeared like an immense sheet of water, the silvery sheen of which contrasted with the sombre hue of the lofty mountains around. Towards the north-east the water-line extended to the horizon, and the river swept in a noiseless, slow current past the foot of the hills beneath him. From here he visited Makoko, who gave him a most friendly reception, and entertained him for twenty-five days. A treaty was finally concluded by which the king placed his states under the protection of France, and ceded a tract of country, to be selected by M. de Brazza, on the shores of the Congo. Another treaty was also arranged with the Ubanji, who appear to occupy the region between the Alima and Stanley Pool. The second French station was placed at Ntamo, on the left bank of Stanley Pool, which M. de Brazza considers the key to the Congo interior. Stanley Pool is 93 miles nearer to the Atlantic coast than is indicated on Stanley's map. By these treaties and discoveries, M. de Brazza maintains that the rights of priority of the French nation are clearly established over the region between the Ogowé, the Equator, and the Congo and over the tract of country on the southern bank of the Congo from Impila to the confluence of the River Djué, to the south of Stanley Pool. The station at Ntamo was established on October 1, 1880, and named Brazzaville. Leaving the station in charge of a sergeant and three men, M. de Brazza tried to find a new route to the sea by the valley of the N'Duo, which empties itself into the Niari and leads from Ntamo to the coast in a nearly due westerly direction. He was obliged, however, to abandon this, and continue his journey down the Congo. He arrived at the Gaboon in December, 1880. Failing to find Dr. Ballay or any reinforcement for his expedition here, he again, for a third time, ascended the Ogowé and reached Franceville in February, 1881, where he found about 100 natives engaged in various industries and the settlement self-supporting. During the following six months preparations were made to transport a steamer, to be sent in sections, from France, from the Ogowé to the Alima-a path being cleared by 400 laborers. This steamer has, however, not yet reached the Ogowé. In October, 1881, M. de Brazza set out from Franceville to endeavor again to explore the Niari valley route, from Stanley Pool to the Atlantic. He was more successful in this second attempt. The Niari proved to be a beautiful river which enters the Atlantic under the name of Quilliou, and flows for a long distance without rapids or falls past a broad, fertile, and densely peopled valley. lying athwart the great parallel terraces over which, ladder-like, the neighboring Congo has cut its bed on its way to the ocean. After many adventures, including a fight with a hostile tribe, M. de Brazza reached the coast at Landana on the 17th of April, 1882. The valley of the Niari is the best line for a railway to Brazzaville or Ntamo. Should the French choose to avail themselves of these discoveries, and occupy and hold the stations established by M. de Brazza, the political as well as geographical results can not fail to be of great importance. The London Athenæum, however, asserts that the road along the Congo is far preferable to the route of M. de Brazza, which is considerably longer, and leads to a part of the coast where communication with the land is only possible in surf-boats, while the Congo is accessible at all times to vessels of the largest burthen. Mr. Stanley has recently returned to Europe. He has now seven steamers on the Congo, and has founded four factories on ground ceded by the native kings. STEARNS' EXPEDITION TO LABRADOR.-The Stearns' Expedition to the coast of Labrador, reached home safely, on the 12th of September. Mr. Stearns went as far north as Triangle Harbor, a few miles |