The same author has also constructed another table exhibiting the vertical range and distribution of the Bohemian Trilobites, classified according to the several stages adopted in his own great works upon the Geology and Paleontology of that area; no less than 183 species are thus appointed in time-their distribution in space is chronicled also in the Thesaurus itself, on pages 72*, 72†, 72, the particulars of every known genus is tabulated, and through it we arrive at the fact that the Silurian rocks of the world contain 126 well-determined genera, and 1640 species; their distribution is given, and summed up for both hemispheres-48 pages of the table is devoted to this order alone. Well may this have been called the Age of Trilobites" by the older authors, for no epoch of the world's history was ever so characteristically typified by a group so peculiar. Coeval and cotemporary with, if not preceding in time, the Trilobita, stand the Brachiopoda. Every ancient sea of the globe seems to have been largely tenanted by this class of mollusca, the group comprises few genera, but is rich in species, no less than 1635 occurring in 47 genera. The most complete analysis as to their distribution and geographical summary is given of this class from page 89 to 126 of the Thesaurus. This order has received more attention from British and Foreign naturalists than any of the mollusca, and no group of fossils have been so well determined. The labours and researches of our own distinguished countryman, Thomas Davidson, F.R.S., into this group of mollusca, have, however, surpassed all other authors. From the Cambrian rocks, through deposits of every age to those still forming in modern seas, this order has lived on, though now but feebly represented [only 11 genera living], 37 having died out. The analytical research of Dr. Bigsby shows us that in the Silurian rocks of the American Continent no less than 1120 species are known, and in the Eastern hemisphere, 1672. Of the 47 known genera, 27 are common to the two divisions of the Globe, 14,1 are exclusively American, and 14 European. The Orthida lived in and were distributed through and over no less than 40 Silurian areas throughout the Globe, 300 species of this family being distributed through the Lower Silurian beds, and 200 in the Upper. Other large genera as-Lingula Atrypa 30 and by way of showing the wide discrepancy amongst the group (or possibly our want of still more perfect knowledge of their distribution than we at present possess) we may instance such genera as the following, which occur only in few areas :Camarium in I country or area. The Primordial genera Lingulella and Lingulepis do not pass to higher stages. After carefully working our way through the pages devoted to the history of this Lower Palæozoic group of Mollusca in "time and space," we are the better able to appreciate highly the labour which the author has gone through, and which has placed before the student, with but few errors, the labours of our ablest Paleozoic Paleontologists; prominently among whom must stand the names of Davidson, Von Buch, De Vernueil, Hall, and Billings-whose results are now for the first time brought together and classified. No group so conclusively forces upon us the importance of those considerations which we have already dwelt upon relative to first appearance, duration, migration, and extinction through time. Up to the close of the Cretaceous period, this order formed a conspicuous part of the marine fauna of every epoch, and one or two genera are still largely represented in the seas of Australia, etc. 1 Camarium, Eatonia, Eichwaldia, Lingulepis, Pholidops, Rhynchospira, Tropidolepsus, Zygospira, Meganteris, Skenidium, Strophodonta, Trimerella, Rennselæria, Trematospira. Echinodermata.-The earliest seas give us also, wherever they are now traceable, countless forms of this class. In the order Crinoidea, 78 genera and 315 species are recorded from the many regions where the Silurian rocks containing this group are known; the Cystideans, 33 and 136 species; the Asteridea, 14 and 90 species, in all 512. Deep interest must always be attached to the distribution and development of this class. The Lower and Upper Silurian stages over the entire world possess a rich assemblage of genera, perhaps the Niagara group of America, the Wenlock Rocks of West Europe, and especially England and Wales, contain the most remarkable forms of Crinoidea known. They are brought together and catalogued in such a manner in the Thesaurus, that we can readily mentally restore the old Silurian submarine Crinoidal forests, and whatever may have been the nature of the water or sediment in which they flourished, we are led to examine and weigh with much interest the results embodied in Table K [Geographical Summary] compiled from the II pages of the Great Table. The comparatively limited geographical range of some genera, and the colonisation of different areas (widely separated) by the same genera, are problems of high interest to the physicist and naturalist,' and the distribution of modern genera in the Caribbean area, Australia, the West Indies, etc., may throw some light upon these remarkable forms of ancient life. America seems to have had two chief foci of concentration widely separated, one in the west, over an extensive old marine area, resulting in the rocks of Illinois, Wisconsin, and Tennessee; the other to the east, in Canada West, and the Northern part of the State of New York.2 17 American Silurian areas are enumerated in the table, showing the wealth or poverty of each, dependent perhaps upon diligent research on the one hand, or condition of sea, etc., non-favourable to life, and development on the other; such, however, is the state of our knowledge at the present time as to the distribution of this order in North America. Three chief areas in the Western Hemisphere abound in the Crinoidea and Cystidea, (the British Islands, Russia, and Sweden), and chiefly in the limestone of the Upper Silurian stages, -the Wenlock Rocks of England and Wales, and the so-called Coralline Limestone of Russia yielding the richest harvest. The unequal distribution of the whole class is singularly detailed in the Thesaurus, which clearly suggests the want of research in given regions. Thus : In Spain we only know of two forms, both Cystideans; in Norway, only nine Crinoids and one Cystidean; and in the classical Silurian district, Bohemia, one Crinoid only — Asocrinus, and 12 Cystideans; these facts may be termed curiosities of distribution, and will remain so until we know more of the areas and their faunas, through future research. Cephalopoda. The names, range, and distribution through the Silurian rocks of 34 genera, and 1419 species, of the Tetrabranchiate,-Odontophora close the Thesaurus. It is rendered still more valuable through the liberality of M. Barrande, who placed his MS. list of this great group at the disposal of the author; thus some 500 species are here notified and stratigraphically placed in the Bohemian Rocks, prior to the completion of Barrande's own work upon the Cephalopoda of the Bohemian Basin. It is impossible to omit notice of these gigantic Lower Paleozoic pelagic Orthoceratites, whose remains swarm in both the Upper and Lower Silurian deposits of every known region of the globe. 37 areas are enumerated in the Geographical Summary at p. 191 in the Thesaurus, 18 in America, and 19 in the Western Hemisphere; two genera contain collectively 1021 species-viz., Cyrtoceras, 317, and Ortheceras, 704; the former distributed through 22 countries, the latter 36. Assuming, which we do not doubt, the transcribed correctness and compilation of the author, the summary of this group is exhaustive; 22 pages are occupied by the genera and species which are spread through every Silurian deposit known, their universality in deposit and area, and widely spread distribution, demonstrates and 1 See the works of Hall, Haydan, Meek, Billings, Schumard, Worthen, De Koninck. 2 21 Genera are common to the Western and Eastern hemispheres; 35 are peculiar to America; and 23 are European. testifies to the immensity of time required for the deposition of this older Palæozoic group of rocks, and the life history of the species in this large and highly organised group, which added to that of the Gasteropoda, forcibly suggests a still more remote and lost fauna, from which these descended, reaching far back to Laurentian, and pre-Silurian ages. The genus Nautilus now represented by one species' (in the Silurian seas by 21) is the only form that has survived through the stream of time, and each succeeding life-period has seen their decrease in number. Space only forbids us entering into further analysis of this important class of mollusca. That numerous errors during the progress of the compilation of the Thesaurus should creep in, and occur, is to be expected, and under certain groups many occur; these are chiefly in the synonomy of the Graptolitida (Hydrozoa)-some 30 species are thus duplicated, arising from the author's misconception of the species placed under several genera by different writers upon this group-especially Hall, Geinitz, and others-scattered through many memoirs. A proper analysis of the large genus Graptolithus as used by Hall, with those adopted by every other author, would have prevented this. Again, many genera of the Phyllopoda, Ostracoda, and Branchiopoda, as now recognized, should have received more careful analysis relative to their synonomy, etc.; the same species occurring, as in the Polyzoa, under different genera.2 These errors give a plus or minus value to the species, and also to the groups, and, where tabulated, are perpetuated in the same ratio, and right or true deductions upon migration, recurrence, locality, and the longevity and extinction of species can only be drawn from correct identification; these errors in the table, however, are readily corrected by those possessing sufficient knowledge, and need not be perpetuated in succeeding analyses, and the author himself may (if not in another edition) do so in some other form. We trust that every scientific library, either private or public, will make a point to possess a copy of this great muster-roll of every species known in the Silurian rocks of the globe. R. E. II.-RELIQUIE AQUITANICE; Being Contributions to the Archæology and Palæontology of Perigord and the adjoining Provinces of Southern France. By EDOUARD LARTET and HENRY CHRISTY. Edited by Prof. T. RUPERT JONES, F.G.S. Parts VI. and VII. August and September, 1868. OUR UR last Notice of this work appeared in the GEOLOGICAL MAGAZINE for June, 1868, Volume V., p. 282. Part VI. concludes the observations and comparisons between the implements, etc., from the Caves of Perigord, and the implements used among the Laps and North American Indians. On this subject the letter of Mr. Robert Brown (who has only lately returned from a protracted residence in Western North America) will be read with great interest. This is followed by "An Account of the Human Bones found in the Cave of Cro-Magnon in Dordogne, by Dr. Pruner-Bey," illustrated by six chromo-lithographic plates. Five of the plates are devoted to the crania, and one to limb-bones. The description of these remains extends into Part VII. At p. 71, Dr. Pruner-Bey writes:-"The presence at all levels of the same kind of flintscrapers, as finely chipped as those of the Gorge d'Enfer, and of the same animals as in that classic station, evidently shows them to be relics of the successive habitation of the Cro-Magnon shelter by the 1 Nautilus pompilius, the only Tetrabranchiate Cephalopod living; in the Silurian deposits there are 1420 known species. The same may be said with reference to many names given in the addenda, some of which it will be seen are repeated in the general text. same race of nomadic hunters, who at first could use it merely as a rendezvous, where they came to share the spoils of the chase taken in the neighbourhood; but coming again they made a more permanent occupation, until their accumulated refuse and the debris gradually raised the floor of the cave, leaving the inconvenient height of only 1.20 mètre (about 4ft.) between it and the roof; and then they abandoned it by degrees, returning once more at last to conceal their dead there. No longer accessible, except perhaps to the foxes above noticed, this shelter and its strange sepulture were slowly and completely hidden from sight by atmospheric degradation bringing down the earthy covering, which, by its thickness alone, proves the great antiquity of the burial in the cave. "The presence of the remains of an enormous Bear, of the Mammoth, of the great Cave-Lion, of the Reindeer, the Spermophile, etc., in the hearth-beds, strengthens in every way this estimation of their antiquity; and this can be rendered more rigorously still if we base our argument on the predominance of the Horse here in comparison with the Reindeer, on the form of the worked flints, and of the bone arrow and dart-heads, and on the above-mentioned indications of hunting, as well as on the absence of any engraving or carving. Hence we may refer this station of Cro-Magnon to the age immediately preceding that artistic period which saw in this country the first attempts of the engraver and the sculptor." He writes, at p. 70, "Amidst the human remains lay a multitude of marine shells (about 300), each pierced with a hole, and nearly all belonging to the species Littorina litorea, so common on our Atlantic coasts. Some other species, such as Purpura lapillus, Turritella communis, etc. occur, but in small numbers. These also are perforated, and like the others, have been used for necklaces, bracelets, or other ornamental attire." etc., etc. Amulets of ivory were also found. The perforated shells, bone implements, flint flakes, etc., form the subject of the six excellent plates accompanying Part VII. III-ON SOME PHENOMENA OF THE WEATHERING OF ROCKS, ILLUSTRATING THE NATURE AND EXTENT OF SUBAERIAL DENUDATION. By D. T. ANSTED, M.A., F.R.S., &c. [From the Transactions of the Cambridge Philosophical Society. Vol. xi. Part II. 1868] PROFES ANSTED here brings forward a number of personal observations on the influence of rain, frost, extreme heat and dryness, and of vegetation acting with the atmosphere in certain cases, in modifying the earth's surface. Fissures produced in rocks, during long continued dry weather, are more extensive and influential than is generally supposed. Valleys "two or three hundred feet in depth, miles in length, and several hundred yards wide," have originated in cracks, and been gradually enlarged by rain. The faces of tracts of country are very much changed from time to time by fissures and the agency of rain and frosts, the position as well as magnitude of these openings being changed, whether by the falling in of their sides, the gradual deposit of new material from water running over the surface, or by their being enlarged to form regular valleys. So rapid do these changes take place, that vegetation cannot well exist; there are no trees-hardly even bushesthere is not time for them to grow. In some districts (Algeria, Ionian Isles, &c.) "an air of wild desolation characterises the landscape," vast naked expanses of loose soil may be travelled over. Vegetation is in a certain sense conservative, as when the ground is overgrown, the denuding effect of the weather is reduced. In his observations on the Channel Islands, Prof. Ansted mentions that the breaking up of the rocks which form the vast and constantly shifting heaps of sienite is due to rain and frost, assisted by vegetation, -the removal alone is effected by the sea, and that imperfectly. In some parts of these Islands the Greenstone Rocks are decomposed, and form a sand and gravel, with apparent boulders of the rock itself. Prof. Ansted gives numerous other notes on the disintegration of rocks, and concludes with a few remarks on the importance of Physical Geography as a key wherewith to unlock some of the mysteries of Geology. Geologists are at the present time so much at variance as to the amount of credit due to Subaërial denudation on the one hand, and to Submarine on the other, that careful observations on the denudations going on at the present time are of the utmost value. So vast is the amount of sediment brought down by rivers, and to such great distances is it carried away by currents and deposited over the bed of the ocean (as Lyell shows in the last edition of his "Principles," vol. i.), that perhaps, when looking at the immense thickness of sedimentary deposits containing marine shells, we are apt to attribute too much to the sea, when a very considerable part of the sediment might have been brought down by rivers, the result of Subaërial Denudation. REPORTS AND PROCEEDINGS. GEOLOGICAL SOCIETY OF LONDON.-Nov. 25th, 1868.-1. "On Floods in the Island of Bequia." By G. M. Browne, Esq. Communicated by the Secretary of State for Foreign Affairs. On the 17th of March, at 8 o'clock P.M., a steady strong wave was seen bearing down upon Admiralty Bay; it had no perceptible crest, and was three feet in height; it encroached upon the land to distances varying from 70 to 350 feet. A second smaller wave followed. No shock of an earthquake was felt. DISCUSSION.-Dr. Duncan wished for some explanation of these earthquake waves, more especially with regard to the effects of supposed cataclysmic waves. He considered that they arose from sudden changes in the level of shoals or littoral tracts, and not from deep-sea disturbances. |