must therefore be content to notice only the more important of them in the order in which they appear.

Dr. Duncan's paper on Echinodermata from the South-eastern coast of Arabia and from Bagh on the Nerbudda is unusually interesting. This paleontologist generally makes remarks worth reading and remembering in connection with the subjects of which he treats, and those contained in this memoir exhibit a more than common breadth of mind. Finding the species he has determined to indicate a Cenomanian age, he discusses the probability of the beds containing them belonging to that period, and devotes a special section of the paper to an essay on "The Impossibility of establishing a close Synchronism between the Asiatic and other Cretaceous Strata." The remarks which follow, "On the Identity, Persistence, and Variability of the Species," are equally good and very suggestive. They at least show us how much we have to learn about the life-history of those types which we call species. The conclusion, that "as the different longevities of species and also of the individuals of species are both regulated by determinate laws, so are, doubtless, the apparently inexplicable associations of persistent, variable, nascent, and moribund species," is sufficient to indicate the nature of the subject discussed. We can here do no more than call attention to the paper, which is worthy of forming an appendix to Mr. Darwin's 'Origin of Species.'

The next paper consists of a letter "On the Fossil Contents of the Genista Cave, Gibraltar," addressed by Mr. Busk and the late Dr. Falconer to General Sir J. W. Codrington, Governor of Gibraltar. The character of the extinct fauna of Gibraltar, according to the evidence yielded by this cave, is not a little peculiar; of the Mammoth, Rhinoceros tichorhinus, Ursus spelæus, Hyæna spelæa, and other English, French, and German forms, "not a vestige has been detected among the fossil remains of Gibraltar." The Carnivora are, however, the most significant; "the three species of Felis are of African affinities, and Hyæna brunnea, now for the first time ascertained to have existed formerly in Europe, is at the present day chiefly found near the Cape of Good Hope and Natal." The last-mentioned discovery opens out a very large question, or series of questions. How did Hyæna brunnea get from Africa to Europe, or from Europe to Africa? In which of these directions did the species migrate ? At what period did the migration take place? Finally, how comes it that this is a South African species? Human remains, stone implements of the polished-stone period, broken querns, pottery, and other objects were also found in the cave, and show that, geologically speaking, its contents are of no great antiquity. The authors conclude their letter by two very good suggestions; firstly, that a local museum should be formed, to contain

objects of interest found on the rock, and nothing else; secondly, that a geological survey of the rock should be made by a competent surveyor. We believe that Professor Ramsay, the Director of the Geological Survey of Great Britain, has undertaken the lastmentioned task, so that we may be sure of its being well done.

Dr. Falconer's posthumous paper "On the asserted Occurrence of Human Bones in the ancient fluviatile Deposits of the Nile and Ganges" has already been noticed at some length.

Mr. Whitaker's three papers on the Chalk of the Isle of Thanet, of Bucks, and of the Isle of Wight are interesting to British geologists, but the special nature of the facts described prevents our discussing them here.

Some curious facts are mentioned in Dr. Stoliczka's paper on the Cephalopoda of the South-Indian Cretaceous Rocks, which will be read with interest in connection with Dr. Duncan's paper already noticed. It is satisfactory to find that these two paleontologists, working independently and upon different classes of animals, come to the same conclusion respecting the age of the Indian Cretaceous strata. Although none of the genera of Cephalopoda from these beds, with the exception of Ammonites, are represented by species which exhibit any remarkable difference from European Cretaceous forms, yet of the genus named there are four species of the group Macrocephali, one of the Planulati, and one of the Fimbriati, which are of course allied to Jurassic forms. "The most striking and abnormal among the Ammonites, however, are three species of the Triassic group Globosi," and Dr. Stoliczka may well have been astonished at their occurrence in such company.

A great deal has lately been said for and against the theory of the atmospheric erosion of river-valleys, of the Valley of the Weald, &c.; and we now have, in Messrs. Foster and Topley's paper "On the Superficial Deposits of the Valley of the Medway, with remarks on the Denudation of the Weald," a carefully prepared account of certain phenomena which are thought by the authors to prove, or at any rate to render it probable, that the Valley of the Weald owes its present surface-configuration chiefly to atmospheric causes. There are those who theorize and speculate without a knowledge of the phenomena they wish to explain; there are again those brilliantminded and experienced men who can propound a probable theory and support it with ability, off-hand, simply from their great knowledge of natural phenomena in various districts; but there are also those equally useful workers in science, who, like these authors, accepting a theory already rendered probable, take a particular district and find out how every individual fact lends additional probability to the view they accept. Of course, in this instance, the conclusion is foregone, but we honestly believe that had the facts

proved adverse they would not have been distorted to harmonize with it. Messrs. Foster and Topley show that an old river-gravel of the Medway occurs 300 feet above the present level of the river; therefore the valley below must have been excavated by sub-aërial causes-" rain and rivers." They also go farther, and say that in this case "there can be but little difficulty in supposing the present form of the ground in the Weald to have been produced entirely by these agents;" this is not yet proven, but is to a great extent highly probable. According to the chronological statement given by the authors, Col. Greenwood was the first to maintain (in 1857) that the valleys were wholly formed by "rain and rivers;" unfortunately, however, his book was but little read by geologists at the time. The question was raised as a question by Mr. Jukes in 1862; but Professor Ramsay has been its great exponent and advocate, and has disposed of most of the objections to his theory that have been advanced by the advocates of marine-denudation. It must not be supposed, however, that rain and rivers are considered by him and his followers to have done all the work; the sea began, and atmospheric agencies completed it.

Two out of Mr. Henry Woodward's three papers on new fossil Crustacea are well worth notice. In one the author proves that Professor de Koninck's Chiton Wrightianus is not a Chiton, but a Cirripede. This fossil was found in the Wenlock limestone and shale of Dudley; it is apparently allied to Loricula and other pedunculated Cirripedes, and thus carries back the first appearance of the group from the Lias to the Upper Silurian.

In another paper, Mr. Woodward describes a new genus of Eurypterida, which he names Hemiaspis. It is remarkable on account of its appearing "to offer just the link we needed to connect the Xiphosura with the Eurypterida." The author also remarks, that "there are several peculiarities about Hemiaspis which seem to offer analogies with the Trilobites." In this chronicle we have thus recorded the discovery of two transition-forms-a Coral and a Crustacean, and we feel confident that the determination of such links between heretofore distinct families is destined some day to form an important element in the solution of the laws which have regulated the origin and succession of life on the globe.

VIII. MINING AND METALLURGY.

FOR Some time past the price of Tin ore, or as it is technically termed, Black Tin, has been so exceedingly low, that throughout the tin-producing districts of the West of England during 1865 not more than six mines have been in a position to pay dividends to the adventurers. This has arisen from three causes: the failure of the American market-the large importation of tin from the Eastern Archipelago and from the British mines forcing considerable quantities of tin upon the market, they being unable otherwise to meet the current expenses of the mines. This state of things has naturally led to a careful examination of the methods of preparing the ores for sale, with a view to the introduction of more economical methods. It is not generally known that the process of separating tin ore (oxide of tin) from the stone in which it is found is one of considerable delicacy. The quantity of tin ore is small compared with the valueless matter with which it is mixed. This will be evident from the following statement of the quantities of tin ore contained in the mass, as it is brought to the surface, from the mines named:

The hard quartzose contents of a mineral vein are brought to the surface from great depths, and the first operation is to reduce it to a state of fine powder, which is suspended in water. This is brought about by the continued action of heavy stamps, and the mud thus produced is made to pass through the "stamps grate" (a perforated plate of copper). This muddy fluid has usually been allowed to flow through long narrow troughs-commonly called strips"-and when these were filled they were emptied by hand; the upper part of the strip containing the portion which was richest in tin, the lower portion being very poor. Dividing the contents of this trough and removing it to other machines, either "frames" or "buddles," was a tedious and, consequently, a costly operation.

Necessity has compelled the miner to reduce this cost as much as possible. This has been very successfully done by the use of the "round buddle," which is a circular table, or trough, slightly inclined from the centre to the circumference. The thick mud flows in at the centre, over the table, and runs off at the edges. By regulating the flow of water, and producing a slight degree of agitation by

means of light brushes, which are made to sweep the surface, all the heavy matter, of course containing the tin, is deposited nearest the centre. Beyond twelve or eighteen inches from which but little tin is found.

Another form of machine has also been recently introduced, which is known as "Borlase's Buddle," being named after the inventor. This "buddle" differs from the ordinary form in delivering the fluid containing the earthy matter and the tin at the circumference, and distributing it towards the centre. The construction of this apparatus will be seen, at once, from the accompanying drawings:

By this arrangement the tin stuff in its state of fine powder int suspension in water is, at once, spread out in a thin sheet, and the