have been issued, in quarto, pp. 274, illustrated by 125 plates: we trust the author may be spared to bring this great work to a conclusion. The curious edentulous reptile, the Rhynchosaurus, is described in the Transactions of the Philosophical Society of Cambridge. The allied but still more extraordinary Dicynodonts and Oudenodonts of South Africa were described in the Geological and Philosophical Transactions. These carry the Saurian grade of structure as far back as the Triassic series. In the Keuper of Germany, fossils had been found which were referred to a genus Mastodonsaurus; and in the older coal-deposits other remains, on which the genus Archegosaurus was founded. Owen, applying the microscope to the structure of the teeth, obtained very striking results, which, with other characters, led him to refer the supposed Saurians to a lower type of reptiles, more nearly akin to the Batrachia, but with affinities to sauroid fishes and saurian reptiles. More decisive batrachian characters were pointed out in the reptile from the coaldeposits of Nova Scotia, which he called Dendrerpeton. The Labyrinthodont type was shown in the Baphetes of the Pictou coal, and in the Parabatrachus of the Scotch Carboniferous series. In the class of Fishes he has added improvements, both on the old system of Cuvier, as also to the more recent one of classification by scales, proposed by Agassiz chiefly for simplifying the study of the imperfect remains of fossil fishes. The entire range of researches on extinct animal species has been condensed and summarized in Professor Owen's work on 'Palæontology,' of which two editions have appeared. (8vo: Black, 1860 and 1861.) So inseparably interlinked have living and fossil forms been in the labours of Professor Owen, that it would be impossible to regard him in a separate light either as an anatomist or a palæontologist, for we cannot fail of speaking of him as both in the very same breath. Neither can we follow his labours in order of time, nor of subject. To-day he is investigating "parthenogenesis," to-morrow the "nature of limbs ;" on one occasion he is demonstrating the existence of entophyta, or parasitic plants, as well as entozoa in the bodies of animals; at another, defining the footprints of fossil animals, and assigning them to the various classes of animals that made them. The paper on the Protichnites, in the Quarterly Journal of the Geological Society, vol. viii. (1852), is a good example of his mode of work in this very difficult line of interpre tation. Owen's discovery, in 1835, of the most extraordinary of human entozoa, the Trichina spiralis, infesting the muscles of the human body in such vast numbers as to produce sometimes cases of violent death in the midst of apparent health; his observations of the "blood-disks" which he published in the Medical Gazette,' in 1839, with other analogous investigations,-impressed him deeply with the value of the microscope for anatomical and physiological researches. Other branches of microscopical study being carried on about this time by Farre, Bowerbank, Busk, and a few other observers, a "Microscopical Society" was formed in 1840, of which Professor Owen was the first President; its proceedings being published under the title of the 'Microscopical Journal and Structural Record,' the first paper in which was by himself, "On the Structure of Fossil Teeth from the Central Division of the Old Red Sandstone, indicative of a new Genus of Fishes-Dendrodus." His study of the microscopic structure of teeth was carried on in a laborious, searching, critical spirit, unsurpassed in any special investigation by any naturalist whatever. He was led to it by receiving, in 1837, from Mr. Darwin fragments of the teeth of the extinct megatherium and other animals from South America, in an incipient state of decomposition, when he was struck with the fact that, instead of their being resolved, like the fossil tusks of the mastodon and mammoth, into parallel superimposed conical lamellæ, they separated into fine fibres arranged at right angles to the plane of the layers. From this he went on to examine the dif ferences in the microscopical structure in the teeth of every class of animals, fish, reptiles, mammals; the result being the production of a book unique for amount, completeness, and value of research, and beauty and correctness of illustrations: his 'Odontography,' in 1840-45, consisting of two thick quarto volumes of 650 pages and 168 most exquisitely executed plates. Owen became a Fellow of the Geological Society in 1836, and the "Wollaston Medal" was awarded to him in 1838. In 1844 he received the Royal Medal from the Royal Society for his admirable description of certain Belemnites preserved with a great proportion of their soft parts in the Oxford clay. No fossil shell had given rise to more conflicting opinions as to the affinities of its construction than the Belemnite. The application of the principles of physiological correlations had indicated its general relationship with the cuttle-fishes; but the speci mens from Christian-Malford, in Wiltshire, presented to the College of Surgeons by the Marquis of Northampton, displayed in a marvellous manner such traces of those soft and perishable parts so essential to determining the true nature of its living form, as to permit no longer any doubt of the nature and character of the animals to which they belonged; and the uncinated arms, the tentacles with their numerous hooklets, the muscular tunic of the mantle, the expiratory tube, the ink-bag and duct, the lining membrane of the stomach, and all the general details of the anatomy of the fossil Belemnites, were compared in the most complete and convincing manner with the corresponding parts of the recent cuttle-fishes and with those of the Nautilus pompilius, first dissected by Mr. Owen in 1831. The Belemnitide, though possessing the chambered and siphonated shell, were thus shown to belong to the higher, or dibranchiate order of Cephalopoda. As examples of anatomical monographs, we may refer to the memoir On the Lepidosiren annectens,' and those on the singular and beautiful Sponge (Euplectella), in the Linnean Transactions; 'On the Rhinoceros ;' On the Giraffe ;' On the Great Anteater;' 'On the Brachiopoda;' On the Aye-aye (Chiromys),' in the Zoological Transactions; On the Development of the Carapace and Plastron of the Chelonia;' On the Dentition of the Phacochoerus ;' 'On the Exogenous Processes of Vertebræ ;' and' On the Placenta of the Elephant,' in the Philosophical Transactions. We cannot, however, attempt to enumerate the many papers that have proceeded from his pen. In the 'Bibliographia Zoologiæ,' published by the Ray Society in 1853, there are recorded upwards of two hundred and thirty of his published productions, and many of these are of the most voluminous and laborious character; and the works that have emanated from him since are not proportionably less in number or importance. His labours have been as varied as numerous, and have extended to every branch of animal life, living and fossil; and it has been justly said of him that," from the sponge to man, he has thrown new light on every subject he has touched." In this series of untiring and uninterrupted researches, Owen has had steadily in view the higher generalizations of his science. The principle of "vegetative or irrelative repetition," hinted at in his 'Synopsis of the Lectures' in 1835, is fully developed in the volume of 'Lectures on the Invertebrate Animals,' published in 1843. (8vo: Longmans; second edition. 1855.) The President of the Royal Society, in presenting to Professor Owen the Copley Medal, awarded to him in 1851, thus alludes to this most important of Owen's scientific labours :— "The progress of all sciences is a perpetual struggle after generalizations of a higher and higher order. Anatomy and physiology, so actively cultivated in the time of Cuvier, had afforded at the latter end of his career glimpses of generalizations, which, under the vague terms of unity of organization,' became subjects of sharp controversy. The idea, so expressed, had two applications,-one, to the analogies which exist between the permanent organization of the lower animals, and certain transitory states of the higher species; the other, to the correspondences traceable between the parts composing the organization of different species. "With reference to the first of these applications, I cannot do better than quote the author's own account of his conclusions, as given in the last lecture of his course on the Invertebrate Animals, published in 1843. "The extent to which the resemblance, expressed by the term 'Unity of Organization,' may be traced between the higher and lower organized animals, bears an inverse ratio to their approximation to maturity. All animals resemble each other at the earliest period of their development, which commences with the manifestation of the assimilative and fissiparous properties of the polygastric animalcule: the potential germ of the mammal can be compared, in form and vital actions, with the Monad alone, and, at this period, unity of organization may be predicated of the two extremes of the animal kingdom. The germ of the Polype pushes the resemblance further, and acquires the locomotive organs of the Monad -the superficial vibratile cilia-before it takes on its special radiated type. The Acalephe passes through both the Infusorial and Polype stages, and propagates by gemmation, as well as spontaneous fission, before it acquires its mature form and sexual organs. The fulness of the unity of organization which prevails through the Polypes and larval Acalephes, is diminished as the latter acquire maturity and assume their special form. 66 6 "There is only one animal form which is either permanently or transitorily represented throughout the animal kingdom,-it is that of the infusorial Monad. "Other forms are represented less exclusively in the development of the animal kingdom, and may be regarded as secondary forms. These are-the polype, the worm, the tunicary, and the lamprey; they are secondary in relation to the animal kingdom at large, but are primary in respect of the primary divisions or sub-kingdoms. "Thus the Radiata, after having passed through the Monad stage, enter that of the Polype; many there find their final development; others proceed to be metamorphosed into the Acalephe or the Echinoderm. "All the Articulata, at an early stage of their development, assume the form or condition of the apodal and acephalous worm; some find their mature development at that stage, as the Entozoa; others proceed to acquire annulations; a head; rudimental feet, jointed feet, and finally, wings: radiating in various directions and degrees from the primary or fundamental form of their sub-kingdom. "The Mollusca pass from the condition of the ciliated Monad to that of the shell-less Acephalan, and in like manner either remain to work out the perfections of that stage, or diverge to achieve the development of shells, of a head, of a ventral foot, or of cephalic arms. "The vertebrated ovum having manifested its monadiform relations by the spontaneous fission, growth, and multiplication of the primordial nucleated cells, next assumes, by their metamorphosis and primary arrangement, the form and condition of the finless cartilaginous fish, from which fundamental form development radiates in as many and diversified directions and extents, and attains more extraordinary heights of complication and perfection than any of the lower secondary types appear to be susceptible of.' "To the second application of the principle I must more particularly refer, as the subject on which perhaps Professor Owen's investigations have been more fully and elaborately and systematically carried out, and have exercised a more important and universal influence on these sciences than any other,-I mean the doctrine of Homologies, or the correspondency of parts and of plan in the construction of animals. This had been the subject of close and sharp discussions in the Academy of Sciences between Cuvier and Geoffroy St. Hilaire, which are summed up by the latter in the 'Principes de Philosophie Zoologique,' published in 1830; and it can be no matter of surprise, that with an antagonist so strong in his well-founded reputation as a great master in science, and so skilful in applying the weapons of a severe and sarcastic logic, Geoffroy St. Hilaire should have failed to impress the physiological world with those views which Cuvier objected to, as being based upon à priori speculation. "The effect of these discussions may be traced in most of the ablest works on Anatomy and Physiology which subsequently appeared, as, e.g. those of Professor John Müller, Professor Wagner, Milne-Edwards, Siebold and Stannius, in Sir Charles Bell's work 'On the Hand,' and in the Outline of the Animal Kingdom' and 'Manual of Comparative Anatomy,' by Professor Jones, of King's College, London. By all these |