sedimentary rocks, is not the only one, and is inadequate to explain the production of many of the varieties of stratified silicated rocks, such are serpentine, steatite, hornblende, diallage, chlo rite, pinite, and labradorite, all of which mineral species form rock masses by themselves, frequently almost without admixture. No geological student will now question that all of these rocks occur as members of stratified formations. Moreover, the manner in which serpentines are found interstratified with steatite, chlorite, argillite, diorite, hornblende, and feldspar rocks, and these, in their turn, with quartzites and orthoclase rocks, is such as to forbid the notion that these various materials have been deposited, with their present composition, as mechanical sediments from the ruins of pre-existing rocks; a hypothesis as untenable as that ancient one which supposed them to be the direct results of plutonic action. There are, however, two other hypotheses which have been proposed to explain the origin of these various silicated rocks, and especially of the less abundant, and, as it were, exceptional species just mentioned. The first of these supposes that the minerals of which they are composed have resulted from an alteration of previously existing minerals, often very unlike in composition to the present, by the taking away of certain elements and the addition of certain others. This is the theory of metamorphism by pseudomorphic changes, as they are called, and is the one taught by the now reigning school of chemical geologists, of which the learned and laborious Bischof, whose recent death science deplores, may be regarded as the great exponent. The second hypothesis supposes that the elements of these various rocks were originally deposited as, for the most part, chemically formed sediments, or precipitates; and that the subsequent changes have been simply molecular, or, at most, confined in certain cases to reactions between the mingled elements of the sediments, with the elimination of water and carbonic acid. It is proposed to consider briefly these two opposite theories, which seek to explain the origin of the rocks in question respectively by pseudomorphic changes in pre-existing crystalline rocks, and by the crystallisation of aqueous sediments, for the most part chemically-formed precipitates. Mineral pseudomorphism, that is to say, the assumption by one mineral substance of the crystalline form of another, may arise in several ways. First of these is the filling up of a mould left by the solution or decomposition of an imbedded crystal, a process which sometimes takes place in mineral veins, where the processes of solution and decomposition can be freely carried on. Allied to this, is the mineralisation of organic remains, where carbonate of lime or silica, for example, fills the pores of wood. When subsequent decay removes the woody tissue, the vacant spaces may, in their turn, be filled by the same or another species. In the second place, we may consider pseudomorphs from alteration, which are the result of a gradual change in the composition of a mineral species. This process is exemplified in the conversion of feldspar into kaolin by the loss of its alkali and a portion of silica, and the fixation of water, or in the change of chalybite into limonite by the loss of carbonic acid and the absorption of water and oxygen. The doctrine of pseudomorphism by alteration as taught by Gustav Rose, Haidinger, Blum, Volger, Rammelsberg, Dana, Bischof, and many others, leads them, however, to admit still greater and more remarkable changes than these, and to maintain the possibility of converting almost any silicate into any other. Thus, by referring to the pages of Bischof's Lehrbuch der Geognosie, it will be found that serpentine is said to exist as a pseudomorph after augite, hornblende, olivine, chondodrite, garnet, mica, and probably also after labradorite, and even orthoclase. Serpentine rock or ophiolite is supposed to have resulted, in different cases, from the alteration of hornblende-rock, diorite, granulite, and even granite. Not only silicates of protoxyds and aluminous silicates are conceived to be capable of this transformation, but probably also quartz itself; at least, Blum asserts that meerschaum, a closely related silicate of magnesia, which sometimes accompanies serpentine, results from the alteration of flint, while, according to Rose, serpentine may even be produced from dolomite, which we are told is itself produced by the alteration of limestone. But this is not all-feldspar may replace carbonate of lime, and carbonate of lime feldspar, so that, according to Volger, some gneissoid limestones are probably formed from gneiss by the substitution of calcite for orthoclase. In this way we are led from gneiss or granite to limestone, from limestone to dolomite, and from dolomite to serpentine, or more directly from granite, granulite, or diorite to serpentine at once, without pass* Hunt on the Silification of Fossils, Canadian Naturalist, N. S., I. 46. ing through the intermediate stages of limestone and dolomite, till we are ready to exclaim in the words of Goethe:"Mich ängstigt das Verfängliche Im widrigen Geschwätz, Wo Nichts verharret, Alles flieht, Wo schon verschwunden was man sicht," which we may thus translate :-"I am vexed with the sophistry in their contary jargon, where nothing endures, but all is fugitive, and where what we see has already passed away." By far the greater number of cases on which this general theory of pseudomorphism by a slow process of alteration in minerals, has been based, are, as I shall endeavour to show, examples of the phenomenon of mineral envelopment, so well studied by Delesse in his essay on pseudomorphs, and may be considered under two heads :-first, that of symmetrical envelopment, in which one mineral species is so enclosed within the other that the two appear to form a single crystalline individual. by staurolite, or staurolite crystals completely enveloped in those Examples of this are seen when prisms of cyanite are surrounded of cyanite, the vertical axes of the two prisms corresponding. Similar cases are seen in the enclosure of a prism of red in an envelope of green tourmaline, of allanite in epidote, and ot various minerals of the pyroxene group in one another. occurrence of muscovite in lepidolite, and of margarodite in lepidomalene, or the inverse, are well-known examples, and, according to Scheerer, the crystallisation of serpentine around a nucleus of olivine is a similar case. This phenomenon of symmetrical envelopment, as remarked by Delesse, shows itself with species which are generally isomorphous or homoeomorphous, and of related chemical composition. Allied to this is the repeated alternation of crystalline lamine of related species, as in perthite, the crystalline cleavable masses of which consist of thin alternating layers of orthoclase and albite. The Very unlike to the above are those cases of envelopment in which no relations of crystalline symmetry nor of similar chemical constitution can be traced. Examples of this kind are seen in garnet crystals, the walls of which are shells, sometimes no thicker than paper, enclosing in different cases crystalline carbonate of lime, epidote, chlorite, or quartz. In like manner, crystalline shells of leuci'e enclose feldspar, hollow prisms of tourmaline are filled with crystals of mica or with hydrous peroxyd of iron, and crystals of beryl with a granular mixture of orthoclase and quartz, holding small crystals of garnet and tour. maline, a composition identical with the enclosing granitic veinstone. Similar shells of galenite and of zircon, having the external forms of these species, are also found filled with calcite. In many of these cases the process seems to have been first the formation of a hollow mould or skeleton crystal (a phenomenon sometimes observed in salts crystallising from solutions), the cavity being sometimes filled with other matters. Such a process is conceivable in free crystals found in veins, as for example, galenite, zircon, tourmaline, beryl, and some examples of garnet, but is not so intelligible in the case of those garnets imbedded in mica-schist, studied by Delesse, which enclosed within their crystalline shells irregular masses of white quartz, with some little admixture of garnet. Delesse conceives these and similar cases to be produced by a process analogous to that seen in the crystallisation of calcite in the Fontainebleau sandstone; where the quartz grains, mechanically enclosed in well-defined rhombohedral crystals, equal, according to him, sixty-five per cent. of the mass. Very similar to these are the crystalloids with the form of orthoclase, which sometimes consist in large part of a granular mixture of quartz, mica, and orthoclase, with a little cassiterite, and in other cases, contain two thirds their weight of the latter mineral, with an admixture of orthoclase and quartz. Crystals with the form of scapolite, but made up, in a great part, of mica, seem to be like cases of envelopment, in which a small proportion of one substance in the act of crystallisation, compels into its own crystalline form a large portion of some foreign material, which may even so mask the crystallising element that this becomes overlooked, as of secondary importThe substance which, under the name of houghite, has been described as an altered spinel, is found by analysis to be the mixture of völlknerite with a variable proportion of spinei, which in some specimens, does not exceed eight per cent., but to which, nevertheless, these crystalloids appear to owe their more or less complete octohedral form.+ ance. (To be continued.) * Annales des Mines, V. xvi. 317-392. + Report Geol. Survey of Canada, 1866, p. 189. Rpt. Geol. Sur. of Canada, 1566, pp. 189, 213. Amer. Jour. Sci, III. i. 188. INSTRUCTIONS FOR OBSERVERS, AT THE ENGLISH GOVERNMENT ECLIPSE EXPEDITION, 1871 II. POLARISCOPIC OBSERVATIONS THE chief points to which observers of polarisation should direct their attention appear to be : A. What is the nature of the outlying corona? B. Can the radial polarisation of the circumsolar corona be traced down to the photosphere, or, if not, how low? C. Is secondary atmospheric polarisation traceab'e? and if so, does the plane change during totality? A. We might suppose this to be due (1) to circumsolar matter (though at a great distance from the sun) reflecting light, (2) to circumsolar matter in the state of self-luminous gas, (3) to circumlunar matter diffracting and, to a certain extent, re flecting light (most improbable),! (4) to lofty atmospheric haze or cloud, of excessive tenuity, diffracting light. The light ought to be, for (1) strongly and radially polarised, (2) unpolarised, (3 and 4) insensibly or all but insensibly polarised. Hence polarisation observations would only serve to discriminate between (1) on the one hand, and (2), (3), or (4) on the other. From the faintness of the object and its considerable extent, the naked eye, armed with a polariscope, might be best. If a telescope be used, it should be of quite low power, and the aperture as large as the breadth of the pupil multiplied by the magnifying-power. Suppose the polariscope be Savart's, the quartz plates being thick enough (if the naked eye be used) to give bands as narrow as, say, 20' diameter. The observer should previously have practised on the blue sky, rotating his Savart till the bands disappear, and noticing to what degree they are brought back by small changes of pointing without rotation, so as to be prepared for what he is liable to from secondary atmospheric polarisation during totality. Should only very feeble bands be seen in the outer corona, such as might possibly be attributable to atmospheric polarisation operating through small changes of pointing, it would be well for control to rotate the instrument a little till bands are fairly visible on the disc of the moon, and notice whether on passing to the outer corona, in whatever direction, the bands, instead of being reinforced, tend rather to be drowned in white light. Should luminous beams or dark rifts be seen in the outer corona, so as to exhibit contrast of light and shade in close proximity, a good opportunity will be afforded of testing whether the light of the outer corona is polarised or not. If it be polarised, then on rotating the Savart, so as to make the bands cut at various indications the boundary of light and shade, the bands will in certain azimuths of the Savart be stronger on the luminous than on the dark side of the edge of the beam or rift. If it be unpolarised, then, whatever be the azimuth of the Savart, the bands will be rather drowned in white light than reinforced on passing from the dark to the luminous side of the edge. But Savart's and other colour-polariscopes, which are admirable for detecting a slight polarisation in light which is not particularly feeble, break down when the difficulty arises from the feebleness of the light rather than the slightness of the polarisation. In such cases a simple double-image prism, with a diaphragm-tube, is better. Unless those who have seen total eclipses can decide from trial (suppose on the clear sky after sunset, or at night when illuminated by the moon), combined with Junction FIG. 1. disapp. Let the observer rotate the polariscope till the bands, if any, seen on the dark moon disappear; then, without rotating the instrument round its axis, let him incline the axis so as to point at the outlying corona in different directions round the sun, and notice whether the bands spring into existence; and if so, let him sweep round the sun, noticing what lies outside the clearly circumsolar corona of 5' or so height, and let him notice particularly by estimation the direction, relatively to the bands, of the radius vector of the region where they are most vivid, or, better, the azimuth of both radius and bands. He should also specify, provided he can do so with certainty, whether the bands were black-centred or white-centred. He should also state in his account, and verify the statement by an observation made at leisure before or after totality, whether his Savart is constructed (or set) so as to have the hands parallel or perpendicular to the principal plane of the Nicol. A very useful adjunct to a Savart's polariscope would be a glass reflector, or else a tourmaline, placed so as to cover a small segment of the field of view near the edge. On account of the possible difficulty of illuminating the reflector in the peculiar circumstances of a total eclipse, a tourmaline would seem to be preferable. It should be placed for the naked eye at the least distance of distinct vision-for a telescope, in or in front of the eye-piece, where a real image is formed so as to be seen distinctly the axis of the tourmaline being parallel to the edge or chord of the segment, and the bands being set perpendicular to this chord. In the event of rotation during the observation, the whole should be rotated together. The question whether the bands are bright-centred or dark-centred, which, in the case of slight polarisation, is difficult to decide, would thus be replaced by the simpler question, whether the bands in the field were of the same character as in the segment (i.c., bright being a prolongation of bright, and dark of dark) or of opposite character. Dark Moon FIG. 2. their memory of the degree of illumination of the outer corona, it might be well that the observer should be provided with and should try both instruments. B. For this a telescope will be required with a magnifying power of, say, 16 or 20. A biquartz seems the best instrument, placed at the common focus of the eye-piece (which should be positive) and objective, and combined with a Nicol's prism, or, if it can be procured, a thoroughly good tourmaline. A tourmaline might be placed over the eye-hole, whereas a Nicol might have to be placed in the body of the eye-piece, which, however, is no particular disadvantage if properly done. Let it be ascertained by previous trial how much a Nicol must be turned from the position in which the two halves are purple alike to make the tints contrast more vividly. Say it is 30°. Suppose the observer on the line of central shadow, so that the limits of disappearance and reappearance will be on opposite ends of a diameter. The biquartz and Nicol have been relatively set so that the line of junction is in the plane of polarisa ion of light extinguished by the Nicol, turn them together before totality 30° (or whatever other angle may have been fixed on) to either side of the diameter of disappearance, and, pointing the telescope to the place of disappearance (Fig. 1), await totality without dazzling the eye. The moment the sun is covered, apply the eye to the telescope, and notice whether there is a vivid contrast of colour right and left of the line of junction of the quartz plates all the way down to the dark moon (Fig. 2), or only in the higher parts of the circumsolar corona. Be ready to repeat the observation before reappearance, with the telescope pointed to the place of reappearance; and meanwhile, if time permits, repeat Prazmou-ki's observation by pointing the telescope, without rotation of the analyser, so that the line of junction bisects the moon, and noticing whether the semi circles of the corona are purple alike where they abut on the junction, and what is the order of colours in the semicircle on receding from the junction. A record as to which is which of the two halves of the biquartz should be carefully preserved. Should secondary atmospheric polarisation be so strong as to throw doubt on the results (which may be judged of by noticing the light on the dark moon), it would be well to rotate the analyser till the two halves seen on the dark moon are purple alike, and then alter the pointing of the telescope, and repeat Prazmouski's observation. It will be observed that the same general principles apply to the elimination of atmospheric polarisation, whether the polariscope employed be a Savart's polariscope, a polariscope with quartz wedges, or a biquartz polariscope. C. This is of little intrinsic interest, its chief use being to clear up possible doubts as to the results obtained by the observers of A and B. Should there be an observer not otherwise employed, he might be deputed to observe the direction of the Savart's bands ca disappearance, both on the dark moon and the surrounding sky, and whether this direction changes during totality. Also it should be specified in which pair of opposite quadrants they were black-centred and in which white-centred. Should this be found impossible or uncertain (the instrument being unprovided with the adjunct mentioned above), the Savart might be used as a simple Nicol by turning it end for end, so that the quartz plates are next the eye; and with this the plane of polarisation might be roughly determined by means of the azimuth of the principal plane of the Nicol when the light most nearly disappears. Should registration of the azimuth be attempted, the Savart would be fixed so as not to be reversible. In that case the observer might be provided with a double-image prism and diaphragm-tube for separate use in case of need. Stoppage of stray light in a telescope designed for polarisation The want of this appears to have occasioned some difficulty at the last eclipse. The simplest way is by a stop, with a hole just large enough to contain the image of the object-glass. Such exists in the erecting eye-piece, where an image of the object-glass is formed in the body of the eye-piece. It exists too, in a Gregorian or Cassegrainian telescope, where the stoppage is imperative. But in an ordinary refracting telescope, with an inverting eye-piece, the eye-hole (from certain motives of convenience) is larger than in front of (i. e. nearer the object-glass than) the bright circle, or image of the object-glass; and unless the tube is sufficiently provided with stops, when a faint object near a bright one is looked at, light from the bright, reflected from the inside of the tube, is Eable to enter the field of view. Large instruments are provided with stops; but I fancy smaller instruments are sometimes turned out without them. This should be looked to. The observer may test the correctness of stopping by taking out the eye-piece, inserting a paper disc with a central hole of the size of the field-glass, turning the instrument nearly but not quite to a bright object, as well as to points more distant from the bright object, and noticing whether the side of the tube, even when viewed in a direction grazing the edge of the hole, is properly dark, so that only the edges of the stops are seen. * On the other hand, the stops should not obstruct a clear view of the object-glass as seen through the hole representing the fieldglass, or they will render the outer portions of the object-glass useless. General Remarks I consider the observation recommended by Mr. Ranyard (see NATURE, Aug. 24, 1871), very important, IF, after what Prazmouski and Ranyard have done, the point be still deemed doubtful. Prazmouski's observation seems to have been beautifully devised and executed, but carelessly described. It is only by conjecture that I can make sense and harmony with what is known, out of his observations as described by himself. But I think that Mr. Ranyard has at least shown that our conjectural interpretation of Prazmouski's observation is the right one; and if so, the point seems settled. It is for this reason that, in lieu of No. 3, first half, I proposed something new. What becomes of the magnesium, &c., which the spectroscope reveals low down in the gigantic puffs which the sun emits? The hydrogen must surely carry the magnesium, &c., with it to the higher regions, though the magnesium, &c., would soon be condensed, and so would not be detected by the spectroscope. These substances would exist in the form of an If reflection occurs from the part of the tube so near the eye as not to appear within the field, it will not signify much. exceedingly fine haze or dust. I use the two words, "haze" to denote a filmy cloud of molten "dust" of solid matter. This haze or dust is capable of detection, and, according to my interpretation, has been detected, by polarisation; and it is interesting to know how low down it can be detected. Mr. Stoney's speculations as to layers are utterly inapplicable here, as they imply a state of tranquillity quite unlike what we now know to exist, at any rate in connexion with the puffs. I don't know why, in the second half of No. 3, Mr. Ranyard prescribes placing the line of junction across a sector or rift, if by that he means turning the eye-piece carrying the quartz plates so that the line is perpendicular with the corona to the sector. It would be more likely to yield results if it cut it obliquely, as represented for the corona in Fig. 2. But probably he only means pointing the telescope so that the junction cuts the rift. If the observer notices contrasting colours, he may then proceed to determine the plane of polarisation. G. G. S. SCIENTIFIC SERIALS "On THE Journal of the Quckett Microscopical Club. No. 16. Ocbeing the address of the President (Lionel S. Beale, M. B., F. R.S.), tober 1871. "Microscopic Work and Conjectural Science,' for the year 1871. This address is chiefly occupied in combating the method, presumed to have been adopted, of depreciating one kind of scientific investigation in order to elevate another, and attacks without ceremony those who would elevate physical science to the disparagement of microscopical observation.the Examination of the Surface Markings of Diatoms by the Oxy-calcium Light," by N. E. Green. The writer of this paper details his examination of such diatoms as Isthmia, Biddulphia, Triceratium, Pleurosigma, &c., as opaque objects by high powers, as one-sixth Ross and one-twelfth Gundlach, through the agency of the oxy-calcium light. The conclusion at which he has arrived is, that the markings on all the above, except Pleurosigma, resemble "craters," the surface "being studded with rows of small shallow craters, the sharp edges of which projected slightly above, while the centres seemed to be below the surface." In Pleurosigma a different structure of the surface was observed. "The lime light brought out most distinctly the bead-like character of its markings; they stood out in bold relief like rows of Indian corn."-The Inaugural Address of the South London Microscopical and Natural History Club, by R. Braithwaite, M.D., F.L.S., is principally devoted to suggestions on the vast field for observation at the disposal of the microscopist.-"On Nucleated Sporidia," by M. C. Cooke, M.A. After describing the general structure which prevails in the genus Peziza of Ascomycetous Fungi, the writer details his method of mounting sections for the microscope in pure glycerine. The nucleated sporidia, so prevalent in this genus, are affirmed to be so affected by this method that in a short time all traces of the nuclei are lost, and the object of the paper is to indicate the doubtful value of nucleated sporidia in specific characters. The true nature of such nuclei and their uses are said to be obscure. IN the Revue Scientifique, Nos. 13-18, are many valuable articles. Further reports are given of the proceedings of the Edinburgh meeting of the British Association, and a translation of Prof. T. Sterry Hunt's address to the Indianopolis meeting of the American Association. We have also a memoir of M. Lartet by M. G. de Mortillet; Helmholtz's paper on the rapidity of propagation of electro-dynamical actions; report of M. Chauveau's lectures on the physiology of virulent maladies; a lecture by M. Claude Bernard on the method and principle of physiology; a translation of P. Secchi's paper on the solar protuberances from the Atti dell' Academia ponitificia de nuovi Lincei; a biographical sketch of Haidinger by M. Fouqué; reports of the proceedings of the various scientific institutions in France and Belgium; and translations of lectures delivered at the Royal Institution, University of Edinburgh, &c., by Prof. Tyndall, Dr. Carpenter, Dr. Laycock, and others. SOCIETIES AND ACADEMIES PARIS Academy of Sciences, October 23.—The greater part of the communications read at this meeting were devoted to chemical subjects. Of mathematical papers only one was presentednamely, a continuation of M. Chasles' memoir on the determina. tion of a series of groups of a certain number of points on a geometrical curve.-A note was read by M. J. Bertrand on the mathematical theory of dynamical electricity, and a memoir by M. E. Mathieu on the integration of equations to the partial differences of mathematical physics.-M. du Moncel presented some observations relating to a recent communication by M. Ruhmkorff upon some experiments in magneto-electric induction, in which he claimed to have already ascertained and published facts analogous to those of the German author -M. P. A. Favre read a continuation of his thermic researches upon the electrolysis of the hydracids. -A fifth letter from Father Secchi on the various aspects of the protuberances and other remarkable parts of the surface of the sun was read, in which he describes the results of simultaneous observations made by himself at Rome, and by M. Tacchini at Palermo.-M. Secchi also presented a note on a new method of observing the eclipses and passages of Venus, by means of a spectroscopic apparatus modified by having at a distance of about 20 centimetres in front of the spectroscope, an additional prism having its refringent angle parallel to the fissure. The chemical papers were as follows:-a theory of simple reactions limited by inverse action, and an application of the same to the transformations of phosphorus, by M. J. Lemoine. -Researches in chemical statics, by M. Stas, containing a discussion of the phenomena which occur in the precipitation of dilute solutions of salts of silver by hydrochloric, hydrobromic, and hydriodic acids, and by chlorides, bromides, and iodides. This paper contains some results of great importance in the analysis of bodies containing silver. The conclusion of the second part of M. Berthelot's investigation of the ammoniacal salts. A note on the transformation of glucoses into monatomic and hexatomic alcohols, by M. G. Bouchardat, communicated by M. A. Wurtz. The author acts upon the glucoses by means of an amalgam of sodium. He describes its action upon glucose and sugar of milk.-A note on the hexabromide and hexachloride of silicium, by M. C. Friedel, also presented by M. A. Wurtz; and a note on the method of determining the gases evolved by an explosion of nitroglycerine, by M. L. L'Hote, presented by General Morin. From the researches of the last-mentioned author it appears that I gramme of nitroglycerine produces 284 cub. centim. of gas, containing by volume 45'72 of carbonic acid, 20 36 of binoxide of nitrogen, and 33 92 of nitrogen. -M. Elie de Beaumont called attention to some specimens of native phosphate of lime from Caylux and Cajare, and noticed the importance of these deposits for agricultural purposes. M. Combes also remarked upon this subject.-M. Chapelas presented a note on a remarkable meteor observed during the night of the 19th October. PHILADELPHIA "Re Academy of Natural Sciences, May 9.-The President, Dr. Ruschenberger, in the chair. - Prof. Cope demonstrated some anatomical points of importance in the classification of some of the Siluroids of the Amazon, noticing first those which have no swimming b'adder, but having the post-temporal bone pierced in a sieve-like manner, forming minute tympana; these he characterised as Otocinclus. Others having huge swim-bladders, gun-boat style of shape. No adipose fin; the back naked. No lyre plate, indicated as Zathorax. A third, body protected by bony shields above. No adipose fin; the scapular arch dermoössified and lyre-shaped below; indicated as Physopyxis lyra A fourth, shielded all over its sides, with the under lip turned back, genus Corydoras. A fifth, where the under lip is separated, except at the ends, forming loops, named Brochis. In the sixth, where the lips are separated from the beard distally forming chin beards, indicated as Dianema. May 16-Dr. Carson, Vice-Presiden', in the chair.mains of Mastodon and Horse in North Carolina."-Prof. Leidy exhibited two photographs, received from Prof. W. C. Kerr, State Geologist of North Carolina, representing some remains of Mastodon americanus found in that State. One of the specimens represented is that of the greater part of the lower jaw of a mature male, retaining both incisor tusks and the last two molar teeth. The latter, with their angular lobes separated by deep angular and nearly unobstructed valleys, are quite characteristic of the species. The incisors are an inch and three-fourths in diameter. The last molar has four transverse pairs of lobes and a well-developed heel. The penultimate molar has three transverse pairs of lobes. The specimen was obtained from gravel overlying the miocene marl near Goldsboro', Lenoir Co., N. C. An isolated last lower molar of the same species, represented in company with the jaw, was obtained in Pitt Co.—Prof. Leidy also exhibited a specimen of an upper molar teeth, which Mr. Timothy Conrad had picked up from a pile of miocene marl at Greenville, Pitt Co., N.C. He suspected, from its size a intricacy in the folding of the enamel of the islets at the mile of the triturating surface, that the tooth belonged to the po pliocene Equus complicatus, and was an accidental occupant the miocene marl. It may, however, belong to a Hipparion the miocene period, but the imperfection of the specimen at inner part prevented its positive generic determination. BOOKS RECEIVED ENGLISH-A Manual of the Anatomy of Vertebratel Animals: P Huxley (Churchills).-A Synonymic Catalog te of Diurad Lepidopte W. F. Kirby (Van Voorst).-Description of an Electri: Telegraph: Francis Ronald (Williams and Norgate) -Spiritual and Animal Magnetis Prof. J. G. Zerffi (Hardwicke) -An Elementary Treatise on Statics: J. Mulcaster (Taylor and Francis). FOREIGN. (Through Williams an 1 Norgate.)-Verhandlungen des int nationalen Congress für Alterthumskunde u, Geschichte zu Bonn. DIARY THURSDAY, NOVEMBER 2. LINNEAN SOCIETY, at 8.-On the Origin of Insects: Sir John Lubbo Bart., F.R.S.-Notes on the Natural History of the Flying Fish: Ca Chimmo-On a Chinese Gall, allied to the European Artichoke Ga A. Müller, F.L.S. CHEMICAL SOCIETY, at 8.- On Anthraflavic Acid: W. H. Perkin. LONDON INSTITUTION, at 7.30.-On Michael Faraday; the Story of his Li Dr. J. H. Gladstone, F.R.S. FRIDAY, NOVEMBER 3. GEOLOGISTS' ASSOCIATION, at 8.-On the Old Land Surfaces of the GD Prof. Morris. MONDAY, NOVEMBER 6. LONDON INSTITUTION, at 4.-On Elementary Physiology (II.): P TUESDAY, NOVEMBER 7. SOCIETY OF BIBLICAL ARCHEOLOGY, at 8.30.-On the Religious Belief of Assyrians: H. Fox Talbot. HACKNEY SCIENTIFIC ASSOCIATION, at 7.30. -Conversazione. ZOOLOGICAL SOCIETY, at 9.-Report on Recent Additions to the Socie Menagerie: The Secretary-On the Recent Zipho d Whales, with a scription of the Skeleton of Berardius arnouxii: W. H. Flower, F.RS On the Habits of the Nose-horned Viper (Vipera nasicornis): Herl Taylor Ussher, C.M.Z S. WEDNESDAY, NOVEMBER 8. GEOLOGICAL SOCIETY, at 8.-Notes on the Diamond Gravels of the Vaal South Africa: G. W. Stow.-On the Geology of the Diamond Fields South Africa: Dr. John Shaw.-Notes on some Fossils from the Devon Rocks of the Witzenberg Flats, Cape Colony: Prof. T. Rupert Jones. Classification of Fruits.-Dr. MAXWELL T. MASTERS, F.R.S. Spectrum of Blood -H. C SORBY, F.R.S. Earthquake in Burmah.-Major CHARLES HALSTED. A Plane's Aspect.-Dr. T. A. HIRST, F.R.S.; Dr. C. M. IN- Geometry at the Universities -RICHD. A. PROCTOR, FR.A.S.. DEEP-SEA DREDGING IN THE GULF OF ST. LAWRENCE. By J. F. WHITEAVES. THE REDE LECTURE AT CAMBRIDGE SIR RODERICK MURCHISON. By Prof. ARCH. GEIKIE, F.R.S. (With THE GEOGNOSY OF THE APPALACHIAN AND THE ORIGIN OF CRYS- SCIENTIFIC SERIALS SOCIETIES AND ACADEMIES BOOKS RECEIVED DIARY PA THURSDAY, NOVEMBER 9, 1871 THE ORIGIN OF GENERA * the co-existence of such parts of such various series at one time as the law of mutual adaptation may permit. "These series, as now found, are of two kinds the uninterrupted line of specifič, and the same uninterrupted line of generic characters. These are independent of each other, and have not, it appears to the writer, been developed ALTHOUGH it is now two years since the publica- pari passu. As a general law, it is proposed to render tion of Prof. Cope's "fragmentary essay," as he modestly terms it, bearing the above title, it may not be out of place, in the present stage of the theory of Evolution, to give our readers some idea of its scope. It ought to be in the possession of every naturalist. Although already so condensed that anything like an analysis of it is impossible, the following tabular sketch may serve to give our readers an idea of the mode in which the Origin of Genera is treated : I. Relations of allied genera. Second; in relation to their development. B. On inexact or remote parallelism. II. Of retardation and acceleration in generic characters. a. The developmental relations of generic and B. Probable cases of transition. Second; earlier metamorphoses. 8. The origin of inexact parallelisms. III. Relations of higher groups. a. Of homologous groups. B. Of heterology. 7. Of mimetic analogy. IV. Of natural selection. a. As affecting class and ordinal characters. B. As affecting family characters. 7. As affecting generic characters. V. Of epochal relations. Professor Cope considers that the laws which have regulated the successive creation of organic beings are of two kinds. The first, that which has impelled matter to produce numberless ultimate types from common origins; the second, that which expresses the mode or manner in which the first law has executed its course, from its commencement to its determined end, in the many cases before us. “That a descent, with modifications, has progressed from the beginning of the creation is exceedingly probable. The best enumerations of facts and arguments in its favour are those of Darwin, as given in his various important works, The Origin of Species,' &c. There are, however, some views respecting the laws of development on which he does not dwell, and which it is proposed here to point out. "In the first place, it is an undoubted fact that the origin of genera is a more distinct subject from the origin of species than has been supposed. "A descent with modification involves continuous series of organic types through one or many geologic ages, and ⚫ "On the Origin of Genera." By Edward D. Cope, A.M., Corresponding Secretary of the Academy of Natural Sciences of Philadelphia. Pp. 80. 1869. (Philadelphia: Merrihew and Son. London: Trübner and Co.) VOL. V. highly probable that the same specific form has existed through a succession of genera, and perhaps in different epochs of geologic time. "With regard to the first law of development as above proposed, no one has found means of discovering it, and perhaps no one ever will. It would answer such questions as this. What necessary coincidence of forces has resulted in the terminus of the series of fishes in the perches as its most specialised extreme? or, of the batrachia, in the fresh-water frogs, as its ultimum? or, of the thrushes, among birds, as their highest extreme? in a word, what necessity resulted in man as the crown of the mammalian series, instead of some other organic type? Our only answer and law for the questions must be, the will of the Creator. "The second law of modes and means has been represented to be that of natural selection by Darwin. This is, in brief, that the will of the animal applied to its body in the search for means of subsistence and protection from injuries gradually produces those features which are evidently adaptive in their nature. That, in addition, a disposition to a general variation on the part of species has been met by the greater or less adaptation of the results of such variation to the varying necessities of their respective situations. That the result of such conflict has been the extinction of those types that are not adapted to their immediate or changed conditions, and the preservation of those that are (pp. 4, 5). In the chapter "On the relations of nearly allied genera," he gives no less than eight "examples of exact parallelism."* "We select one at random as illustrating the large number of facts he brings to bear on the subject of which he treats. "The Cervidae of the Old World are known to develop a basal snag of the antler at the third year; a majority of those of the New World never develop it, except in abnormal cases in the most vigorous maturity of the most Northern Cariacus : while the South American Subulo retains to adult age the simple horn of the second year of Cervus. Among the higher Cervidæ, Rusa and Axis never assume characters beyond an equivalent of the fourth year of Cervus. In Dama, on the other hand, the characters are assumed more rapidly than in Cervus; its third year corresponding to the fourth of the latter. Among American deer there is the Blastocerus, whose antlers are identical with those of the fourth year of Cariacus. "Now, individuals of the genus Cervus of the second year do not belong to Subulo, because they have not as yet their mature dentition. Rusa, however, is identical with those Cervi whose dentition is complete before they gain the antlers of the fifth year. When the first trace of a snag appears on one beam of Cariacus virginianus, the *The author applies the term exact parallelism to the relation of genera which are simply steps in one and the same line of development; while incomplete parallelism is applied to that of those where one or more characters intervene in the maturity of either the lower or higher genera to destroy identity. C |