by the preceding process, is an objection, though it has the advantage of being applicable on a larger scale, and requires no fuel but for the distillation of the amalgam; it is the old method. Third method. The finely divided ore is roasted with common salt as in the first method, then placed in a vat with salt and water; the silver is thus converted into a chlorid, which is stirred up and then passed into a smaller vessel, to collect the heavy earthy particles, and thence into a third, where pieces of copper cause a decomposition of the chlorid of silver, the pure metal being precipitated and a chlorid of copper formed; this is passed into a fourth vessel where fragments of iron cause a precipitation of the copper. By this process, which is simple, the copper-of which there is generally a considerable quantity -is also saved; it is as yet employed but on a small scale at Sanche, near the mine of Moran, to test its value. Fourth method. The fine powder from the pounding mills is mixed with lime, scoria, iron and oxyd of lead (litharge), and then thrown into a smelting furnace with alternate layers of coal; a portion of the sul phur combines with the oxygen of the lime and litharge, and with the iron, passing off in the first two cases as sulphurous acid gas, and in the third forming sulphuret of iron; whilst the remainder, uniting with the base of the lime, forms sulphuret of calcium; this with the scoria forms a melted mass, which falls to the bottom of the furnace, and flows off at a lateral orifice. By this process the silver is reduced to the metallic state, but as the amount is small and disseminated through the mass, it would, to a considerable extent, be carried off by the scoria and lost; hence the lead is employed, to collect the particles of silver and thus form an alloy, which flows out at the lower portion of the smelting furnace. This alloy is now placed in shallow basin furnaces, and whilst in a melted state, strong currents of air are forced over its surface, which oxydize the lead and with it all the baser metals, and the silver remains pure; the dross being blown away by the draughts of air. This is the best process for the rich ores, and in the works of the English mining company, is, I believe, always employed for their reduction. The silver is frequently alloyed with gold, which, when of sufficient value, is separated at the mint, and after deducting expenses, the remainder is returned in coin to the owners. III. ZOOLOGY. 1. On the Structure of the Jaws and Teeth of the Iguanodon; by Dr. MANTELI., (Proc. Royal Society; Lit. Gaz., London, June 17, 1848.) The recent discovery of a portion of the lower jaw with teeth of an adult Iguanodon, having enabled the author to obtain decisive evidence as to the structure of the maxillary organs of that gigantic herbivorous reptile, the results of his investigations are embodied in the present communication. The first memoir on the teeth of the Iguanodon was published in the "Philosophical Transactions for 1825;" but, owing to the fragmentary and water-worn condition in which bones of terrestrial vertebrated animals occur in fluviatile deposits, from their being composed of materials transported from far-distant lands by powerful streams and currents, nearly a quarter of a century elapsed before any portion of a jaw retaining teeth was discovered. The most important relic of this kind is described in this memoir; it consists of the anterior part of the right side of the lower jaw, comprising about two-thirds of the dentary bone, and was discovered by Captain Lambart Brickenden, who, in the true spirit of a man of science, liberally placed it at the disposal of Dr. Mantell, as the original discoverer of the fluviatile origin of the wealden formation of the southeast of England. This bone is eighteen inches long; and if the proportions of the maxillary elements in the Iguanodon were the same as in the recent Iguana, the entire jaw must have been four feet in length. It contains several of the new or successional teeth in their natural position, and there are sockets in the alveolar plate for nineteen or twenty mature mo lars; but all these teeth are wanting, having evidently been dislodged before the bone was imbedded in the stone. The mature teeth, which in their abraded state resemble those of the used molars of herbivorous mammalia, appear to have been arranged in a closely set series. The teeth in the lower jaw were placed with their flat enamelled striated face towards the inside of the mouth, while those in the upper were disposed in the opposite position-namely, with the enamelled ridged face of the crown externally; and the teeth of the upper and lower series were subalternate or intermediate in their relation to each other, as in the ruminants. The anterior part of the lower jaw, which forms the symphysis, presents a most remarkable deviation from all known reptilian types; the alveolar parapet, instead of being continued round the front of the mouth, and bearing teeth, as is the case in all saurians, is edentulous, and at the distance of four or five inches from the front of the chin, suddenly contracts in a vertical direction, becomes procumbent, and expands horizontally to meet the corresponding portion of the opposite ramus of the jaw: the two symphysial portions when united, forming a deep scoop, bear considerable analogy to the corresponding part in the Edentata, especially in the extinct colossal Mylodon. Along the external surface of the jaw there is a row of very large vascular foramina; and the symphysial margin is also perforated by numerous similar openings for the passage of blood-vessels and nerves to the integuments and lips-a certain indication of the great development of the soft parts which covered the maxillary organs. The upper jaw, of which a considerable part, collected by the author, is now in the British Museum, confirms the inferences deduced from the examina. tion of the lower jaw and teeth. The author, with the able assistance of Dr. Melville, instituted a comparison between the fossil teeth in his own, and in the British Museum, with those of existing lizards, and the result of their labors is fully detailed in this memoir. The light shed on the structure and functions of the dental organs of the Iguanodon by these recent discoveries, confirms in every essential particular the inferences deduced by Dr. Mantell from the detached teeth alone, and detailed in his memoir in 1825; and it also reveals the remarkable fact, that this saurian herbivore, which equalled in bulk the gigantic Megatherium and Mylodon, and was destined, like them, to obtain support by the comminution of vegetable substances, was also furnished with a large prehensile tongue and fleshy lips, to seize and retain the foliage and young branches which constituted its food. Among the many extraordinary deviations from known forms disclos ed by palæontology, there is not one more remarkable than this modification of the type of organization peculiar to the class of reptiles, to meet the exigencies required by the economy of a lizard, placed under similar conditions with the colossal Edentata of the tertiary periods and the herbivorous mammalia of more modern times, and designed to hold the same relative position in the economy of nature. From the recently discovered specimens, the author states he has been able to determine that the portion of a lower jaw of a Saurian, with numerous fangs of teeth, described in his memoir in 1845, as probably that of a young Iguanodon, belongs to a distinct genus of the same family; and he proposes to distinguish it by the name of Regnosaurus Northamptoni; the specific designation being a tribute of respect to the noble President of the Royal Society. 2. Notice of Fragments of Trilobites of gigantic size in the Cabinet of Dr. Julius S. Taylor., Carrollton, Montgomery County, Ohio. -During the year 1847, Dr. Taylor kindly furnished us with a cast of the most remarkable fragmentary portions of the "Isotelus megistus" that we have ever seen. A notice of which we inadvertently failed to give at the time of the donation. Dr. Taylor said, "that the specimen from which this cast was made was found in the blue limestone resting upon a stratum of greenish 'marlite' clay," about fifty feet from the upper surface of the blue limestone, which limestone is said to be the equivalent of the Trenton of New York and Silurian of England. The cast presents five or more portions of the shield, the post-abdomen and other portions of the Isotelus which bear the most indubitable evidence of having belonged to trilobites of the most gigantic size on record. Professor Locke, M. De Verneuil and other scientific gentlemen having visited my cabinet concur this opinion.-(I am indebted to Professor Locke for the cast.) At the time of my finding the specimens, I also found portions of at least one hundred different individuals of the same species, varying in size from one half an inch to six inches in length, proving, that the trilobites like the limulus were gregarious. In connection with this specimen, I also found a most delicate and beautiful " Retepora," entirely new, which has been described and figured by my friend, John W. Van Cleve, Esq., of Dayton, and called "Retepora nitida." We have also received from Dr. Taylor, years ago, a full suite of fossils descriptive of the geology of the county of Montgomery, Ohio, in a most beautiful state of preservation, of which he informed us that he had numerous duplicate specimens which he would most gladly exchange for fossils or minerals of any other section of country. 3. Water Tubes in Fishes, (Proc. Bost. Soc. Nat. Hist., April 19, 1848, p. 27.)-Prof. AGASSIZ made some remarks on the existence of numerous minute tubes in fishes, opening externally, which have hitherto been considered mucous tubes, but which he is convinced are tubes for the introduction of water into the body. These openings in some fishes are extremely numerous, existing over the whole external surface. In freshwater fishes, and in those living in shallow waters, they are comparatively few. They are most numerous in fishes which swim at great depths. In reply to a question of Dr. Wyman, he said that he had not as yet found them in the sharks and rays. These openings are sometimes visible to the naked eye, and sometimes require a magnifying power for their detection. They are very large and numerous, and easily seen, in the head of the common shad. These minute tubes unite into larger ones, in a manner which seems to be the same in each class. He thought this circumstance might be of some value in the classification of fishes. The tubes grow larger and larger as they approach the heart. They open into the circulating system near the heart. Prof. A. had injected the heart through these tubes, and had drawn blood from them by a syringe. He had injected the external surface through a single tube, and that whether opening near the head or the tail, or in other parts of the body. He believes these tubes an apparatus for the safety of fishes living at great depths, to enable them to resist the pressure to which they must there be subjected. He did not deny the existence of mucous tubes in fishes, for there are such, about the heads of sharks for instance, from which mucus may be obtained by pressure; but he is sure, that what have been hitherto considered as mucous tubes, are in reality water tubes. 4. Structure of the Foot in Embryo-Birds, (ibid, June 7, p. 42.)— Prof. AGASSIZ had recently made some observations on the structure of the foot in the embryo of birds, which he thought would throw new light on the classification of birds, and perhaps call for radical changes in the system now in use. He had examined the feet of the embryo of Turdus migratorius, Hirundo riparia, Sylvia æstiva, and Fringilla melodia, and found the following appearances in all. The four toes, which in the mature bird are separate, three being directed forwards and one backwards, are in this state all directed forwards, and webbed. There is as yet no trace of bone in them; there are only rows of cartilaginous cells in the position to be occupied by bone, which are more closely grouped together at the points where the joints are destined to appear. The lower extremity is, in fact, at this time, a fin. The upper extremity is in a similar condition, presenting, however, only three rows of cartilaginous cells, united by a membrane. As this condition of the extremities exists in different families, Prof. A. thinks that the present grouping of all web-footed birds together, may be incorrect; particularly since they differ as much among themselves in other respects as they do from land birds. He found that the bill of the immature robin resembled that of a vulturine bird, being straight near the base, and curved at the extremity, the upper mandible being longer than the lower. This would seem to indicate that the vulturine form is a lower type than it has usually been considered. This appeared to derive confirmation from the great resemblance of the bill of some of the water birds to that of some of the vulturine family, that of the genus Lestris, for example. Some of the birds of prey also have another point of resemblance to water birds, in a rudiment of a web between two of the toes. Hereafter, birds having all their toes direct ed forwards, must be regarded as of a lower type than those which have one directed backwards; as, for instance, the pelicans and cor morants among water birds, and the genus Cypselus among swallows. From the result of his examinations of the embryos of birds, Prof. A. had recently, before a scientific society, ventured to predict that hereafter, among the higher mammalia, the foot of the embryo would in the same way be found to be webbed, like that of the seals and cetacea. Prof. Jeffries Wyman immediately afterward confirmed the truth of the prediction in the case of the fœtus of a cat. A similar appear ance had been figured as existing in the human embryo, but its philo sophical bearing had not been before noticed. 5. American and European Oyster-catcher, (ibid, p. 43.)-Dr. CABOT read a statement of the comparative measurements of the American and European oyster-catcher. His observations tend to confirm the opinion of the distinctness of the two species, which have sometimes been confounded with each other. 6. Dr. M. Barry's Physiological Discoveries, (Jameson's Jour., July, 1848, p. 194.)-In the last number of the British and Foreign Medical Review, edited by Dr. Forbes, a distinguished physiologist has the following remarks in regard to Dr. Martin Barry's important physi ological discoveries : The writer of the remarks in question, after shewing the importance of the combination of anatomical and physiological investigations with zoological researches, states that M. Milne Edwards, in several of his later Memoirs, has even adopted the principle, that embryology affords our best and surest guide in classification; as it is by the study of development that we are enabled most certainly to distinguish between those essential characters on which affinity depends, and those accessory characters which are engrafted (so to speak) on the original type for some special purpose. This doctrine was first formally enunciated by him in a Memoir on the Principles of the Natural Classification of Animals, published by him in 1844: in which he points out that the condition of the earliest germ of all animals is the same; namely, the simple cell: that the earliest phases of its development differ according to the sub-kingdom to which it belongs, whether radi * A very minute remnant of vitelline duct found at 18 inches from vent. 56 |