generalisation as to the probable gold-bearing nature of the Australian quartz-country, and as to the probable aspect of the interior of Africa, are probably familiar to most people. But in later years what has especially brought his name into prominence is the chivalrous devotion with which he has maintained one might almost say the national belief in the welfare of Dr. Livingstone. Yet this is only a sample, though one which has come more publicly before us, of the tenacious friendship and active benevolence which have always marked him. As President of the Geographical Society-a society which is in a sense his own creation-he had frequent opportunities of befriending not only the cause of geography but the personal well-being of travellers, and he never failed to use them. The geographers have good cause to lament the death of their chief.

Of the man himself, what he was as he lived and moved among us, his loss is too recent to permit us justly to speak. We can only think of him as the stately courteous old gentleman, carrying even to the last that military bearing which dated from the days of Wellesley and Moore, kindly and thoughtful in his kindliness-a man whose friendship, once given, even ingratitude and injustice could not wholly alienate. He was not without some of the littlenesses of humanity, but they were so transparent, and often even so child-like, that we forget them in the recollection of all the goodness of heart and strength of head and nobility of nature which have gladdened us for so long, but which are now only subjects of tender remembrance.

AL

ARCH. GEIKIE

HOMOPLASY AND MIMICRY

LL students of the remarkable phenomenon of superficial resemblances in the animal and vegetable kingdom will be glad that Prof. Dyer has published an extension of the paper which he read on this subject at the Edinburgh meeting of the British Association. It is especially satisfactory that he has abandoned the very objectionable term "pseudomorphic," and substituted that of homoplastic," a very much better term, because it simply expresses a fact without committing one to any theory. There are, however, one or two points in his paper of last week, on which I should wish to be allowed to comment.

And

Prof. Dyer holds that the distinction between "mimicry" in animals and "homoplasy" in plants, is "sufficiently obvious," the difference assigned being, apparently, that in the one case it takes place between species found in the same locality, in the other between species unconnected geographically. I doubt, however, whether facts will warrant this distinction. The most remarkable instances of "mimicry" among animals hitherto published are, undoubtedly, in the case of species inhabiting the same area; but I am inclined to think that, when attention is called to the subject, others will be found between animals not so associated, though these instances would naturally not attract so much observation. secondly, homoplasy in plants does frequently occur in species occupying the same area. The statement reported to have been made by Prof. Dyer at Edinburgh that “the resembling plants are hardly ever found with those they resemble," would scarcely be borne out by a careful investigation. The real objection to the terms "mimicry' and "imitation is that they seem to imply a conscious effort at convergence, which will hardly be conceded in the case of Lepidoptera any more than of Ferns. The substantial difference betweeen the two is that, in the case of animals, the resemblance appears to be protective, while in the case of plants, there is seemingly no such benefit arising from it; but this is a difference in result and not in the nature of the phenomenon itself. I fail to see that the objections to the use of these terms in the case of

plants do not equally apply to animals; we have no reason to suppose that the two sets of phenomena are not produced by similar causes.

Prof. Dyer states, and no doubt truly, that the external resemblances of plants may frequently be traced to the effect of similar external conditions, and quotes in support Mr. E. R. Lankester's view with regard to animals. But in assuming that this explanation will account for all such phenomena if fully investigated, I think too much is assumed. Cases of homoplasy are referable to two distinct classes-resemblances in general habit, and resemblances of particular organs. The former, as in the case of the homoplasy between a Cactus and a Euphorbia or a Stapelia, or between a Kleinia and a Cotyledon, are no doubt due to the operation of similar external conditions of climate and soil. But in the second class this explanation wholly fails.

As illustrations of the kind of resemblance I mean, I may refer to the two collections of “mimetic plants” exhibited by Mr. W. W. Saunders at the two last soirées of the Linnean Society, a list of which will be found in NATURE for May 26, 1870, and May 4, 1871. The extraordinary resemblance in the markings of the leaves in plants thus grouped together, might well deceive the most experienced botanist. To account for this homoplasy on the ground of similar external conditions, is to start a mere hypothesis, without any facts to warrant it. A still more curious series of resemblances occurs in the case of

fruits than of leaves, so close that it has deceived botanists of the experience of the elder Hooker, Bentham, and Kunth into placing species in a genus with which they have no structural affinity whatever. I have in my mind in particular two samaroid fruits, both from the forests of Brazil, so absolutely identical in external facies, that distinction is quite impossible without dissection, and yet belonging to exceedingly remote orders. I will not, however, say more on this point, as it would be impossible to appreciate the closeness of the homoplasy without drawings, which I hope shortly to be able to publish. The singular part of this resemblance is, that, as far as we know, it is never protective. In our Bee-orchis we have what might well have been assumed primâ facie to be a case of protective resemblance, the flower being so fashioned in order to attract bees to assist in its fertilisation. It is remarkable, however, that the Bee-orchis is one of the few plants that appear to be perpetually selffertilised, never being visited by insects. It is just possible that we have an instance of protective or rather beneficial resemblance of scent in the case of the carrionlike odour of the flowers of Stapelia, which attracts bluebottle and other flies.

In a paper read at the recent meeting of the American Association for the Advancement of Science, by Prof. E. D. Cope, I find the following thoughtful remarks :-" Intelligence is a conservative principle, and will always direct effort and use into lines which will be beneficial to its possessor. Thus, we have the source of the fittest, ¿.e., addition of parts by increase, and location of growthforce directed by the will, the will being under the influence of various kinds of compulsory choice in the lower, and intelligent option among higher animals. Thus intelligent choice may be regarded as the originator of the fittest, while natural selection is the tribunal to which all the results of accelerated growth are submitted. This preserves or destroys them, and determines the new points of departure on which accelerated growth shall build."

Biologists generally are, probably, hardly prepared to apply the terms intelligence" and "will" to the vegetable kingdom; but the use of the term “vegetable life" seems to me to imply of necessity that there are powers at work in the economy of the plant, as of the animal, which it is vain to attempt to reduce to manifestations of the forces which govern the inorganic world.

ALFRED W. BENNETT

NOTES

In our present number we give a portion of Prof. T. Sterry Hunt's Address at the Indianopolis meeting of the American Association, and propose in following numbers to reprint some of the more important papers read at the meeting. The next meeting will be held at San Francisco, and the following officers were elected for the meeting of 1872: President, Prof. J. Lawrence Smith, of Louisville; Vice-President, Prof. Alex. Winchell, of Ann Arbor; Permanent Secretary, Prof. Joseph Lovering, of Cambridge; General Secretary, Prof. E. S. Morse, of Salem; Treasurer, William S. Vaux, of Philadelphia; Auditing Committee, Dr. H. Wheatland, of Salem, and Prof. II. L. Eustis, of Cambridge; Standing Committee, Ex Officio, Messrs. Smith, Winchell, Lovering, Morse, Vaux, Gray, Barker, P'u'nam. Committee from the Standing Committee to arrange for next meeting, Profs. J. L. Smith, Asa Gray, Joseph Lovering, in connection with a committee from the Association at large, consisting of Profs. J. L. Smith, J. D. Whitney, and 0. C. Marsh.

THE Senate of the University of London on Wednesday last week exercised for the first time its privilege, under the Public Schools Act, of appo'nting a member of the governing body of Ragby and Charterhouse Schools. To Charterhouse it appointed Mr. Busk, F. R. S., President of the Royal College of Surgeons, thus recognising the claims of science in the direction of education. To Rugby it nominated Dr. Temple, Bishop of Exeter (late head master of Rugby).

THE Inaugural Meeting of the Newcastle College of Physical Science on Tuesday last week was a great success. The Council decided unanimously, on the application of upwards of seventy Ladies, to make no distinction of sex in the admission of pupils, placing all on a footing of exict equality. The total number of students admitted up to the time of the inaugural ceremonial, was fifty-one. In contrast to this we may note that last week the governing body of the University of Edinburgh rejected by a small majority Dr. Alexander Wood's motion, "That, in the opinion of this Council, the University authorities have, by pub. lished resolutions, induced women to commence the study of medicine at the University; that these women, having prosecuted their studies to a certain length, are prevented from completing them for want of adequate provision being made for their instruction; that this Council, without again producing any opinion on the advisability of women studying medicine, do represent to the University Court, that, after what the Senatus and Court have already done, they are at least bound in honour and justice to render it possible for those women who have already commenced their studies to complete them."

ACCORDING to M. Le Verrier, Prof. Alluard of ClermontFerrand has obtained a grant of the necessary funds for establishing his long-projected observatory on the summit of the Fay-de-Dome.

FATHERS Secchi and Denza and M. Diamilla Müller are engaged in organising a series of researches in the Mont Cenis tunnel, for the purpose of ascertaining what variations gravity and magnetism may undergo there.

THE Mayor and other inhabitants of the town of Belfast lately

expressed their sense of Prof. Wyville Thomson's many efforts for the encouragement of Science, and for the improvement and gratification of the working classes, in a suitable address, accompanied by a valuable service of plate.

THE Bulletin Astronomique gives the following observations of Tuttle's comet. From M. Borrelly of Marseilles :-October 12, Marseilles M.T., 16h 29m 195, R.A. 9h 9 44 68, Decl. + 44° 16' 15"*1. The come: had the appearance of a diffuse nebulosity

m

=

badly deaned; it appeared elongated in the direction N. W. by S. E.; it was feeble but of moderate extent, about 2' 20". The approximate correction of Mr. Hind's ephemeris, given by this first observation, is ▲ a = + 0.5, Δ δ = +1° 3. From MM. Loevy and Tisserand of Paris :-Oc.ober 14, Paris M. T. 12h 36m 125.2, R.A. 9h 14TM 355*29, polar distance, 47° 12′ 13′′ '1. The comet resembled a whitish nebulosity, diffuse, and of ir regular form. Its diameter was about 3'; the light scarcely that of a star of the 13th magnitude.

DR. HOOKER, of Kew, has placed the Lichens which he collected during his Morocco expedition in the hands of the Rev. W. A. Leighton, of Shrewsbury, for examination and determination.

THE first Servian Agricultural Exhibition was opened with great ceremony at Belgrade, on October 2.

IN addition to the announcements last week, the following works are in preparation :-From Edward Stanford :-The Laws of the Winds Prevailing in Western Europe, by W. Clement Ley, with charts, diagrams, &c., Part I.; Notes on the Geography of North America, Physical and Political, intended to serve as a text-book for the use of elementary classes; Notes on the Geography of South America, intended to serve as a text-book for the use of elementary classes. The following additional volumes are also announced to Weale's Series, publisbed by Lockwood and Co. -Analytical Geometry and Conic Sections, by J. Hann, new edition, entirely re-written by J. R. Young, numerous diagrams; Treatise on the Construction of Iron Bridges, Girders, Roofs, and other Structures, by Francis Campin, C. E., numerous illustrations; Drawing and Measuring Instruments, by J. F. Heather, M. A., numerous woodcuts; Optical Instruments, by J. F. Heather, M. A., numerous woodcuts; Surveying and Astronomical Instruments, by J. F. Heather, M. A., numerous woodcuts; Physical Geology, partly based on Portlock's "Rudiments of Geology," by Ralph Tate, numerous woodcuts; Historical Geology, partly based on Portlock's "Rudiments of Geology," by Ralph Tate; Emigrants' Guide to Tasmania and New Zea land, by James Baird, B.A.; Workman's Manual of Engineering Drawing, by J. Maxton, seven plates and nearly 325 woodcuts; Mining Tools, for the Use of Mine Managers, Agents, Students, &c., by W. Morgans; Atlas to the above, containing 235 illustrations.

A NEW horticultural Magazine is announced to be shortly commenced, with the title of The Garden, under the editorship of Mr. W. Robinson, F. L. S., author of "Hardy Flowers," "Alpine Flowers for English Gardens," &c.

A COMPLETE geological and statistical history of Australia by C. E. Meinicke, with a magnificent coloured map by A. Petermann, appears as a supplementary number of Petermann's Mittheilungen."

66

THE Ven. Archdeacon Pratt has reprinted a lecture on "The Descent of Man in Connection with the Hypothesis of Development," delivered at the Dalhousie Institute, Calcutta, on July 28, in which the Darwinian doctrine of evolution is vigorously combated.

THE High Wycombe Natural History Society has resolved meetings had become pleasant social gatherings rather than in upon a new course of action suggested by the fact that its any way furthering the pursuit of natural science. In future the meetings will be held at the house of the President, the Rev. T. H. Browne, F.G.S., and will partake more of the nature of classes for the study of certain subjects. A loss in the number of members is expected, but it is hoped that those who remain will benefit by the change. Other local societies would do well to adopt a somewhat similar arrangement. The Quart.rly Magazine of the above body is discontinued.

ASSISTANT-SURGEON VERCHERE, of the Indian Army, has suggested, says the Medical Times and Gazette, that some experiments should be made with reference to meteorological influences on sickness and health. Medical Meteorology in India is still all but an unknown science, and, as at present studied, is useless to medical practitioners. The long range of "readings" tells us nothing; but a register of the effects of meteorological conditions on the men selected for the purpose, with all conditions of exposure, &c, taken into account, and compared with the average sickness of a corps for the same period, would teach us more in a few months than yards of meteorological tables. We understand that the Sanitary Commissioners of India are favourable to the proposal of Mr. Verchere, and it will therefore, probably, be carried out.

On

THE Wigtonshire Free Press says that the foundation of a lake dwelling has been discovered by Mr. Charles Dalrymple, Kineliar Lodge, Aberdeenshire, on a small circular island at the south end of the Black Loch, Castle Kennedy. removing the surface soil, a circle of stones was discovered, the diameter of which was between 50 and 60 feet. On digging deeper through the stratum of forced earth and stones, three feet thick, what appeared to be a different and older layer of soil was reached. Among this black earth were found wood ashes, bits of calcined bones, and flat stones placed contiguously. Immediately below the stones, at the depth of a few inches, an artificial flooring was discovered, formed of the trunks of oak and alder trees. At this point the level of the loch was reached, and the influx of water prevented further excavations in a downward direction. In 1865-6, by the draining of Dowalton Loch, in the same county, several lake-dwellings were exposed; in the spring of this year, when the White Loch of Castle-Kennedy, which is now in connection with the Black Loch by a short canal, was being dragged with a net for trout, the net brought up a canoe of ancient make. In all likelihood it was the ferry-boat, or one of several perhaps, used by the lake-dwellers.

THERE is a volcanic eruption going on in the Hawaian Islands at Maunalva, but its exact site has not been recognised. From Kowa the lava was seen at night to rise to a height of several hundred feet in a column. The eruption is supposed to be near the locality of that of 1868, while others think it is nearer the summit of the mountain, on the scene of the great

IN the same presidency, in the Parambalore district, a maneating tiger has appeared, and killed four men, so that the Government has taken him into consideration, and placed a price of 30%. on his head.

THE Island of Gorgona, off the coast of Choco, is much complained of by ship captains for its electric storms, and its irregular currents. It has held this reputation since the time of

Pizarro.

A VALUABLE discovery of workable lead ore is announced from Jersey.

THE latest report from Tasmania in regard to the experiments for introducing salmon and trout into that country, shows that while the success of the cultivation of both is extremely probable, the existence of trout of large size is unmistakeable.

COAL has been found in large quantities on the banks of a stream flowing into the Godavery, about 224 miles from Juggianet, and ninety-six from Budrachellum. It is close to the surface, and it is extremely probable that fresh deposits will be found in the adjacent British territory.

TPE

Ir is to be noted that on the night of the 21st of August a very severe earthquake was felt at Callao, in Peru, at 8.32 P. M. The undulations were from N.W. to S. E. The shock was of fifteen seconds' duration. It was also felt severely at Cero, Azul, and Pisco. The sea, which previously had been unusually calm, suddenly became very rough, and a strong southerly wind set in. For two days the sea remained very rough at Cero Azul. shock severely shook the ship while it lasted. The observations were confirmed by the steamship Colon. The It was felt six

miles to the west ward of Chala Point at 8. 50 P. M. ship time, and the sea almost immediately thereafter became agitated. E

MEASURES are being taken by the Chilian Congress to prohibit the destruction of timber, particularly in the neighbourhood of springs. The timber districts of the provinces of Llanquihue, Valdivia, Chiloe, and of the Magellan territory are exempted from the law.

Cocos Island, in lat. 5° 30′ N. in the Pacific Ocean, about 600 miles west of the Columbian coast, has now for some years been occasionally occupied by treasure seekers on a legend of a treasure buried by buccaneers. At present it is again abandoned, but

on the southern slope of Maunalva.

THE Constantinople earthquake is now known to have originated in the southern region of the island of Scio, where it began strongly, growing weaker towards its northern circumference. At the Dardanelles it was much sharper than at Rodosto, while at Boorgas, on the Black Sea, it was very slight, and further on at Varna was not felt.

ANOTHER Small place to be marked soon as a big one is Chimbote on the coast of Peru. Its harbour, the finest in the South Pacific, can shelter the navies of the world. It was a great town in the times of the Incas, as remains of a colossal aqueduct will show. Near it are coal mines. It has been abandoned and neglected on account of the difficulties of access, but a railway is now to be constructed to the fertile interior at a cost of 6,400,000/. To the map of Bolivia must be added the small town of Calama in the new mining district of Caracolas.

EXPERIMENTAL farms are now being extended in the Madras presidency-a most essential step for agricultural improvement and practical instruction.

THE Government of Madras has been ordered to furnish special information on the Neilgherry nettle fibre plant.

On the 4th July a most destructive typhoon attacked Hiogo, in Japan,

flat, as stated in many newspapers, but is volcanic, and 2,000 feet high. It is covered with timber and scrub, and being visited by frequent and heavy rains is always green. The place is riddled with shafts, some 150 feet deep. It produces nothing eatable.

THE valuable timber so abundant in the North Island of New Zealand is deserving of a better fate than to be cut down wholesale and used as firewood. The rimu, or red pine, is most valuable for furniture and all ornamental work; the matai, or black pine, is more brittle and heavy than the other, but will take a most beautiful polish; whilst the totara, another so-called pine (for they are none of them Conifera), is easily worked both green and dry. There is also the rata, "that wonderful vegetable production forming itself out of numberless vines, which first receive their support from some full-grown tree, then enclose it in a deadly embrace, and gradually expel the remains of their foster parent as their own growing demands for space require to be satisfied, then finally uniting themselves form a solid tree, with all the characteristics of bark, sap and heart, roots, trunk, and branch." This rata is almost the toughest wood known, and is used in many places for the cogs of wheels, &c. Besides these there are many others, especially the makia, which when thoroughly dry would turn or break the edge of the best axe ever produced in Sheffield, which are now only cut down for firewood as occasion requires.

v.p.27.

T.PE

THE GEOGNOSY OF THE APPALACHIANS AND THE ORIGIN OF CRYSTALLINE ROCKS*

coming before you this evening my first duty is to announce the death of Prof. William Chauvenet. This sad event was not unexpected, since, at the time of his election to the presidency of the Association, at the close of our meeting at Salem in August 1869, it was already feared that failing health would prevent him from meeting with us at Troy, in 1870. This, as you are aware, was the case, and I was therefore called to preside over the Association in his stead. In the autumn of 1869, he was compelled by illness to resign his position of Chancellor of the Washington University of St. Louis, and in December last died at the age of fifty years, leaving behind him a record to which Science and his country may point with just pride. During his connection of fourteen years with the Naval Academy at Annapolis he was the chief instrument in building up that institution, which he left in 1859 to take the chair of Astronomy and Mathematics at St. Louis, where his remarkable qualities led to his selection, in 1862, for the post of Chancellor of the University, which he filled with great credit and usefulness up to the time of his resignation. It is not for me to pronounce the eulogy of Prof. Chauvenet, to speak of his profound attainments in astronomy and mathematics, or of his published works, which have already taken rank as classics in the literature of these sciences. Others more familiar with his field of labour may in proper time and place attempt the task. All who knew him can however join with me in testifying to his excellences as a man, an instructor, and a friend. In his assiduous devotion to scientific studies he did not neglect the more elegant arts, but was a skilful musician, and possessed of great general culture and refinement of taste. In his social and moral relations he was marked by rare elevation and purity of character, and has left to the world a standard of excellence in every relation of life which few can hope to attain.

In accordance with our custom it becomes my duty in quitting the honourable position of President, which I have filled for the past year, to address you upon some theme which shall be germane to the objects of the Association. The presiding officer, as you are aware, is generally chosen to represent alternately one of the two great sections into which the members of the Association are supposed to be divided, viz, the students of the naturalhistory sciences on the one hand, and of the physico-mathematical and chemical sciences on the other. The arrangement by which, in our organisation, geology is classed with the natural history division, is based upon what may fairly be challenged as a somewhat narrow conception of its scope and aims. While theoretical geology investigates the astronomical, physical, chemical, and biological laws which have presided over the development of our earth, and while practical geology or geognosy studies its natural history, as exhibited in its physical structure, its mineralogy and its paleontology, it will be seen that this comprehensive science is a stranger to none of the studies which are included in the plan of our Association, but rather sits like a sovereign, commanding in turn the services of all.

As a student of geology, I scarcely know with which section of the Association I should to-day identify myself. Let me endeavour rather to mediate between the two, and show you somewhat of the two-fold aspect which geological science presents, when viewed respectively from the stand-points of natural history and of chemistry. I can hardly do this better than in the discussion of a subject which for the last generation has afforded some of the most fascinating and perplexing problems for our geological students; viz., the history of the great Appalachian mountain chain. Nowhere else in the world has a mountain system of such geographical extent and such geological complexity been studied by such a number of zealous and learned investigators, and no other, it may be confidently asserted, has furnished such vast and important results to geological science. The laws of mountain structure, as revealed in the Appalachians by the labours of the brothers Henry D. and William B. Rogers, of Lesley and of Hall, have given to the world the basis of a correct system of orographic geology,+ and many of the obscure geological problems of Europe become plain when read in the light of our American experience. To discuss even in the most

summary manner all of the questions which the theme suggests, would be a task too long for the present occasion, but I shall endeavour to-night in the first place to bring before you certain facts in the history of the physical structure, the mineralogy and the paleontology of the Appalachians; and in the second place to discuss some of the physical, chemical, and biological condi tions which have presided over the formation of the ancient crystalline rocks that make up so large a portion of our great eastern mountain system.

I. THE GEOGNOSY OF THE APPALACHIAN SYSTEM.-The age and geological relations of the crystalline stratified rocks of eastern North America have for a long time occupied the attention of geologists. A section across northern New York, from Ogdensburg on the St. Lawrence to Portland in Maine, shows the existence of three distinct regions of unlike crystalline schists. These are the Adirondacks to the west of Lake Champlain, the Green Mountains of Vermont, and the White Mountains of New Hampshire. The lithological and mineralogical differences between the rocks of these three regions are such as to have attracted the attention of some of the earlier observers. Eaton, one of the founders of American geology, at least as early as 1832, distinguished in his Geological Text-book (2nd edition) between the gneiss of the Adirondacks and that of the Green Mountains. Adopting the then received divisions of primary, transition, secondary and tertiary rocks, he divided cach of these series into three classes, which he named carboniferous, quartzose, and calcareous; meaning by the first schistose or argillaceous strata such as, according to him, might include carbonaceous matter. These three divisions in fact corresponded to clay, sand, and lime-rocks, and were supposed by him to be repeated in the same order in each series. This was apparently the first recognition of that law of cycles in sedimentation upon which I afterwards insisted in 1863.* Without, so far as I am aware, defining the relations of the Adirondacks, he referred to the lowest or carboniferous division of the primary series the crys talline schists of the Green Mountains, while the quartzites and marbles at their western base were made the quartzose and calcareous divisions of this primary series. The argillites and sandstones lying still farther westward, but to the east of the Hudson River, were regarded as the first and second divisions of the transition series, and were followed by its calcareous division, which seems to have included the limestones of the Trenton group; all of these rocks being supposed to dip to the westward, and away from the central axis of the Green Mountains. Eaton does not appear to have studied the White Mountains, or to have considered their geological relations. They were, however, clearly distinguished from the former by C. T. Jackson in 1844, when, in his report on the geology of New Hampshire, he described the White Mountains as an axis of primary granite, gneiss, and mica-schist, overlaid successively, both to the east and west, by what were designated by him Cambrian and Silurian rocks; these names having, since the time of Eaton's publication, been introduced by English geologists. While these overlying rocks in Maine were unaltered, he conceived that the corresponding strata in Vermont, on the western side of the granitic axis, had been changed by the action of intrusive serpentines and intrusive quartzites, which had altered the Cambrian into the Green Mountain gneiss, and converted a portion of the fossiliferous Silurian limestones of the Champlain valley into white marbles. + Jackson did not institute any comparison between the rocks of the White Mountains and these of the Adirondacks; but the Messrs. Rogers in the same year, 1844, published an essay on the geological age of the White Mountains, in which, while endeavouring to show their Upper Silurian age, they speak of them as having been hitherto regarded as consisting exclusively of various modifications of granitic and gneissoid rocks, and as belonging "to the so-called primary periods of geologic time." They however considered that these rocks had rather the aspect of altered paleozoic strata, and suggested that they might be, in part at least, of the age of the Clinton division of the New York system; a view which was supported by the presence of what were at the time regarded by the Messrs. Rogers as organic remains. Subsequently, in 1847, § they announced that they no lorger considered these to be of organic origin, without however retracting their opinion as to the paleozoic age of the strata. Re-erving to another place in my address the discussion of the geological age of the White Mountain rocks, I proceed to notice briefly the

Amer. Jour. Sci., II. xxxv. 166.
Geology of New Hampshire, 160-162.
Amer. Jour. Sci., II. i. 411.
Ibid, II. v. 116.