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II. GEOLOGY AND NATURAL HISTORY.

1. On the Mineralogy of Eozoon Canadense.-Dr. ROBERT HOFFMANN of Prague has submitted to chemical and mineralogical investigation the Eozoon Canadense, found at Raspenau in Bohemia, (Jour. für prakt. Chemie, May, 1869). He describes the Eozoon mass as having a superficial resemblance to that of Canada, appearing in waved or concentric bands, oval in form, or else in irregular acervuline aggregates. In the oval banded portion the shell of the Eozoon, a nearly pure, finely granular calcite, can be separated from the mineral representing the sarcode, which is described by Hoffmann as a cast of the soft parts of the Eozoon, formed through infiltration of watery solution either during the growth or immediately after the death of the animal. It is a peculiar silicate, fine-grained, grayish-white and somewhat translucent, the analysis of which is given below, (I). Associated with this is a finely granular dolomite, destitute of any traces of organic structure, which sometimes appears to have served as a center or point of attachment to the growing Eozoon. In other cases, however, broken fragments of older Eozoon had served as nuclei, and become surrounded with a fresh growth. These materials, which constitute what Hoffmann has described as the Eozoon reef, are associated with two other silicated minerals. One of these, allied to fahlunite, has a specific gravity of 2.687, is grayish-brown or greenish-black in color, dull, or with a somewhat fatty luster, and nearly opaque. This substance, whose analysis is given under II, forms nearly parallel streaks in the central parts of the Eozoon reef, and moreover surrounds it, intersecting and wrapping around the Eozoon mass in multiplied layers, a line or more in thickness, which are interlaminated with a light green mineral, transparent, with a somewhat vitreous luster, and a density of 2.56. It is a hydrous silicate (III), allied to picrosmine and is more or less penetrated by magnesite.

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The band of Eozoon rocks at Raspenau lies between silicated schistose rocks beneath, and overlying beds of granular limestone, some of them grayish white, and others blackish from an admixture of carbonaceous matter. One of these gave to analysis 1.100 of carbon, 2.332 of insoluble matter, and 4.708 of carbonate of * Akalies determined by loss; some soda was present.

magnesia, the remainder being carbonate of lime. The composition of the Eozoon shell is given under IV, that of the dolomite under V, and that of the magnesite which penetrates the silicate, III, under VI.

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2. On a Mineral Silicate injecting Paleozoic Crinoids; by T. STERRY HUNT, F.R.S.-A Silurian limestone from near Woodstock, New Brunswick, lately examined microscopically by Dr. Dawson, was found by him to consist almost wholly of comminuted organic remains, including fragments of trilobites, gasteropods, brachiopods, and joints of small encrinal stems and plates; the whole cemented by calcareous spar in a manner similar to many organic limestones. He observed, however, that the pores of the crinoidal remains were injected by a peculiar mineral, readily distinguishable in thin transparent sections, or on surfaces which had been exposed to the action of an acid, which dissolves the carbonate of lime and places in relief the injecting mineral. The minute structure thus revealed is precisely similar to that of recent crinoids studied by Carpenter, and will soon be described and figured by Dawson. Decalcified specimens exhibit a congeries of curved, branching and anastomosing cylindrical rods of the replacing mineral, sometimes forming a complex network, which, under the microscope, resemble the coralloidal forms of aragonite known as flos ferri, and present a frosted crystalline surface. The same mineral, as observed by Dr. Dawson, occasionally occupies larger interstices among the fragments, and was evidently deposited before the calcareous spar which cements the whole mass.

When this limestone is dissolved in dilute hydrochloric acid, the residue, washed by decantation, equals from five to six per cent of the weight of the mass, and is seen under a microscope to consist entirely of the casts composed of the mineral just noticed, mixed with about one-fourth of coarse siliceous sand. This matter is pale grayish-green in color, but when calcined becomes of a bright reddish-brown, without change of form. Heated in a close tube it gives off water, and becomes much darker in color. It is partially attacked by strong hydrochloric acid, which takes up much protoxide of iron; but is readily and completely decomposed by hot concentrated sulphuric acid, leaving a skeleton of silica which, by a dilute solution of soda, is readily separated from the intermingled grains, more or less rounded, of colorless vitreous quartz. The analysis of 1187 grams, effected by decomposing it in the way just mentioned, yielded silica 3290, alumina 2440,

protoxide of iron 1593, magnesia 0360, potash 0140, soda 0042, water 0584, insoluble quartz 3420 1.1869. This calculated for 100.00 parts of the silicate gives as follows; silica 38.93, alumina 28-88, protoxide of iron 18-86, magnesia 4.25, potash 169, soda 0.48, water 6.91. The analysis of another portion of 526 grams by fusion with an alkaline carbonate gave, by calculation for the silicate, 18.80 of protoxide of iron, and amounts of alumina and combined silica closely agreeing with those found above. The oxygen ratio for Si, H, R, H, is as 20-77: 13:46: 6-29: 6.14, or nearly as 3: 2:11. This mineral approaches closely in composition to jollyte, but differs from it in containing a portion of alkalies, and but one half as much water. In these respects it agrees closely with a silicate found by Robert Hoffmann with the Laurentian Eozoon of Raspenau, (Jour. für prakt. Chem., May, 1869, and this volume, page 378). This latter is compared by Hoffmann to fahlunite, to which species also jollyte is allied in physical characters as well as in composition (Dana's Mineralogy, page 493.) Under the names of fahlunite, pinite, etc., is included a great class of hydrated silicates, which, from their imperfectly crystalline condition, have generally been regarded, like serpentine, as the results of the alteration of other silicates. It is, however, difficult to admit that silicates found in the condition described by Hoffmann, and still more the present mineral, which injects the pores of paleozoic crinoids, can be any other than original depositions, allied in the mode of their formation to the serpentine, pyroxene and other minerals which fill the chambers and canals of the Laurentian Eozoon, and to the glauconite which occurs in a similar manner in Tertiary and recent shells. The limestone from Woodstock, apart from the insoluble matters just described, is very pure, yielding only 1.80 p. c. of alumina and iron-oxide, and magnesia equal to 1.35 p. c. of carbonate.

Montreal, March 10, 1871.

3. On native amorphous Mercuric Sulphide.-G. E. MOORE has recently examined a specimen of black mercury-ore collected in Lake county, California, by Professor Whitney. It occurs as a coating on the sides of cracks and crevices in a peculiar quartzose gangue, and is accompanied by crystallized and massive iron and copper pyrites, and very minute cochineal-red crystals of cinnabar. Its physical properties are thus given:-Entirely without structure or cleavage. Fracture semi-conchoidal to uneven, fracture-surfaces brilliant. Very brittle when struck or bent, yet tough when cut. Rubbed in an agate mortar the powder becomes a solid mass, taking a high polish and a metallic luster like graphite. Color grayish-black. Luster metallic. Streak on porcelain pure black. Cut surfaces brilliant. Hardness about 3 on Mohs's scale, somewhat greater than cinnabar, though difficult to estimate exactly on account of its brittleness. Specific gravity 7.701 to 7.748; somewhat different in different specimens on account of admixed cinnabar. Before the blowpipe it behaves like cinnabar. In the closed tube, it sublimes completely, with the exception of a trifling residue of quartz and iron oxide. The black sublimate yields a

cinnabar-red powder when care is taken that the upper part of the tube is heated to near the subliming point of the cinnabar. A qualitative analysis showed mercury and sulphur, with small quantities of iron and silica. Quantitatively examined it yielded as follows:-Sulphur 13.82, mercury 85 79, iron 0-39, quartz 0.25. Whence its composition is

HgS, 98-92; FeS2, 0.83; Quartz, 0.25 100'00. Experiments to determine the chemical cause of the difference in properties between this mineral and cinnabar, resulted negatively. Moore concludes that the mineral in question is completely identical with the black amorphous mercuric sulphide of the laboratory, and proposes for it the name Metacinnabarite.-J. pr. Ch., II, ii, 319, Nov. 1870.

G. F. B.

4. Freieslebenite and Diaphorite.-Von Zepharovich has shown (Sitz. Acad. Wiss. Wien, 1871), that Freieslebenite includes two species of similar composition (Ag1Pb,Sb,S,,) but different crystallization. He retains the original name for the monoclinic species and gives the name diaphorite to the orthorhombic. The former is from Freiberg and Hiendelaencina in Spain, and has for the ratio of the inclined diagonal, the orthodiagonal and the vertical axis 1: 0.5871: 09277; and the inclination of the last is 87° 46′; sp. gr. 6.35. The diaphorite is from Przibram and Freiberg, and has for the ratio of the diagonals and vertical axis 1: 0·4919: 0-7344; and sp. gr.=5.90.

5. On the Eocene beds of Utah; by T. A. CONRAD. (From the author.)-I am indebted to Prof. Cope for an opportunity to examine some Eocene fossil shells, collected at Aspen station, and at Quaking Asp Ridge, east of Bear river, Utah, at an elevation of 7,100 feet. These fossils were taken from the rock in which they were imbedded, by Lucius C. Ricksecker, engineer on the Pacific Railroad. They are imbedded in indurated clay, and suggest the probability that they lived in a river rather than a lake, especially as there is a genus of Cyrenidæ (Veloritina Meek) as well as one of Corbulida (Anisorhynchus Conrad) which lived apparently in company with Unionida and Melaniida. These fossils are especially interesting in consequence of the light they cast on the condition of the globe in the earliest Eocene period. This group immediately overlies the Cretaceous strata, and corresponds with the Lignite beds at the base of the Paris Eocene and those of Provence described by Matheron, which is the first supracretaceous group of strata known to occur in Europe, and according to Matheron has a "colossal development;" and of his first stage of Lignite, he remarks that where the lower bed is in contact with the chalk, it shows fragments of marine shells not easily determined, but he recognizes Ostrea and Cardium. This is probably the broken up surface of the Cretaceous formation which emerged above the sea, a condition naturally following the agitation of the waters of a retiring ocean. Upon this bed follows five stages of Tertiary Lignite of fresh water origin, the lower beds containing Unio Toulouzanii (Loxopleurus Meek), Cyrena globosa, and C. Fesrusssaci. This mixture of fresh and brackish water genera corresponds with

the lowest beds of the Eocene in North America. This exact correspondence in stratigraphical position between the European and American older Eocene, as well as in the hydrography and topography of the respective continents at that period, is elucidated by the affinity of the fossils as regards their peculiar generic characters. Thus the genus Loropleurus Meek originated and died out with the older Eocene fauna. This was also the case with Veloritina Meek, a genus closely allied to if not identical with a genus which Deshayes regards as Cyrena, but arranges in a separate section (C. Trigones). He describes ten species of the Paris basin and Matheron one from Provence (C. globosa). This genus is unknown in later Eocene strata. A gasteropod of the family Melaniidæ cannot be distinguished generically from one in the Lignite beds of Provence, named Melanopsis armata by Matheron. This is the Tiara (Pyrgulifera) humerosa Meek. It is a well characterized genus, very distinct from Tiara and more nearly related to Melanopsis Ferrus. It is also limited to the lower Eocene, and was probably an estuary or brackish water shell, although its nearest living form is Varena crenocarina, which inhabits the Pedro Branca river, Bahia. Lox pleurus Meek is related on one side to Castalia and on the other to Trigonia, which latter genus apparently became extinct in the Cretaceous era, for it is unknown in Tertiary formations, and reappears in the actual seas with very different external characters and I think without genetic descent from the fossil species.

The marine equivalent of this lower Eocene formation is probably to be found in the division B, of Mr. Gabb's Cretaceous fossils of California.

The hydrography of this early Tertiary era may be imagined from the foregoing statement to have been a river system analogous to that of Brazil at the present time. The presence of vast numbers of estuary shells forbids us to suppose that the group inhabited lakes rather than rivers, which rose in not greatly elevated hills, for mountains, except as isolated peaks, had hardly been developed at this period, when the great basin of Utah was submerged, and the Mississippi valley and its rivers were not yet formed, but the general drainage was into the Pacific ocean. There was then a system of great rivers and a densely wooded country eminently fitted for land animals, whose remains I have no doubt are to be found, if they have not been already obtained. The elevation of this vast region to any considerable height took place in the first stage of the Eocene era, and if we are surprised at the great extent of such brackish water rivers, we have only to glance at a similar river system 2,200 miles up the Amazon. By the rise of the Cretaceous formation, this condition of the country was formed, and as no transition beds are known, the advent of new genera and species so different from what had lived before is an unexplained phenomenon in the geological history of the globe. So far in Europe, I believe, no authentic account has been published of any fossiliferous beds between the lower Eocene and the Cretaceous strata, that would indicate a transition period to have

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