On the Fossil Mammalia from the Stonesfield Slate. by E

FOSSIL MAMMALIA FROM THE STONESF1ELD SLATE. 407 On the Fossil Mammalia from the Stonesfield Slate. By E. S. Goodricli, F.L.S., Assistant to the Linacre Professor of Comparative Anatomy, Oxford. With Plate 26. EVER since the discovery, made some eighty years ago, of Mammalian remains in the Stonesfield Slate near Oxford, these fossils have excited the interest of naturalists, and have been the subject of much discussion amongst geologists and palaeontologists both in England and abroad. Nevertheless something still remains to be described in the few specimens which exist; and, while one of them has not yet been figured at all, others have been only inaccurately represented. I therefore propose to write a short history of each fossil, as far as it is known, giving figures when necessary; and to sum up the most important results which have been reached with regard to them by previous authors, together with some remarks as to the bearing of the facts ascertained by a careful study of the teeth belonging to these remains on the general question of the origin and homology of the cusps of Mam- malian teeth. Besides the fragment of the multituberculate form Stereo- gnathus, which I shall mention later, there are only twelve undoubted fossil Mammalian remains from the Stonesfield Slate at present known; ten of these are lower jaws, two are limb bones. Six of the fossil jaws are in the Oxford Museum, one in the York Museum, one in the private collection of 408 E. S. GOODBICH. Mr. Parker of Oxford ;l the two remaining jaws and the limb bones are in the British Museum. Through the kindness of Professor Green and of Professor Lankester, who placed the Oxford fossils in my hands for the purpose of displaying them in a museum case in a manner more worthy of their interest and value, I have had the oppor- tunity of examining and handling our six specimens. I am much indebted to Dr. Henry Woodward for allowing me to examine the two British Museum fossils, and to Mr. Parker for lending me his. To the authorities of the Museum at York I must express my thanks for lending me the excellent specimen in their keeping; but more especially to Professor Lankester, who spared himself no trouble in obtaining for me this privilege, and who has further given me much help during my researches. It may here be mentioned that I have been able, by carefully working away the matrix with sharp needles under Zeiss's dissecting microscope, to expose new cusps, and in some cases new teeth, in five of the jaws described. My figures, which I have endeavoured to make as faithful as possible, differ, therefore, considerably from those previously published. The formation from which these fossils were obtained be- longs to the Lower Jurassic period; whence the great interest attached to them, for at the time of their discovery they were by far the earliest known remains of warm-blooded Vertebrates, —being, in fact, the first Mesozoic Mammalia obtained. Since then, as is well known, remains of a few fossil Mammalia have been found both in England and elsewhere in strata belonging to the Triassic age; as, for instance, Microlestes in England, Dromatherium in America, and Tritylodon in South Africa. The two fossil limb bones mentioned above have been figured and described by Professor H. Gr. Seeley (29). As, unfortunately, they afford no clue to the relationship of the animals whose jaws are described below, there being no proof 1 Mr. Parker also has in his possession a toothless fragment of a jaw which may perhaps be Mammalian. MAMMALIA 1?KOM THE STONBSFIJSLD SLATE. 409 that these bones belonged to any of them, I need only mention that Seeley considers that they are "limb bones indicating a generalised insectivorous type, modified from a Monotreme stock in the direction of the Marsupial plan." Genus AMPHITHERIUM. Four of the fossil jaws appear to belong to this genus. Three of these, two of which are type specimens, are in the Oxford Museum; the fourth is in the British Museum. Amphitherium Prevostii, Blainville. Type specimen, PI. 26, fig. 1. A left ramus of the lower jaw, seen from the inside; in the Oxford Museum. In 1824t1 Dr. W. Buckland, the well-known geologist, first announced the discovery of the remains of mesozoic Mam- malia in his paper' on Megalosaurus' (5). He there mentions " two portions of the jaw of the didelphys or opossum," which he refers " to this family on the authority of M. Cuvier, who has examined it." From Mr. W. J. Broderip we learn that these rare fossils were obtained as follows:—" An ancient stonemason living at Heddington . made his appear- ance in my rooms at Oxford with two specimens of the lower jaws of mammiferous animals, embedded in Stonesfield slate. One of the jaws was purchased by my friend Professor Buckland, who exclaimed against my retaining both" (4). The fossil purchased by Broderip himself is the type specimen of Phascolotherium (see below); Buckland's fossil is the type specimen with which we are now concerned. He placed it in the Ashmolean Museum, whence it has come with the other specimens of the Buckland collection to its present home, the Oxford University Museum. The exact date at which it was purchased I have been unable to ascertain for certain; it was probably about 1814: the date given by Zittel is 1812 (32), but I know not on what authority. Cuvier, who visited Oxford in 1818, says of these fossils 1 Not 1823, as is generally stated to be the case. 410 E. S. GOODRICH. that "lors d'une inspection rapide que j'en pris h Oxford, en 1818, [ils] me semblerent de quelque Didelphe;" and adds in a note that the jaw of Amphitherium " est celle d'un petit carnassier dont les machelieres resemblent beaucoup a celles des Sarigues, mais il y a dix dents en serie, nombre que ne montre aucun carnassier connu" (8). This note was written after the examination of some careful drawings of Buckland's fossil and of the type specimen of Amphilestes (see below) sent to him by Prevost, who was then travelling in England. These announcements of the discovery of Mammalian remains in stone belonging to the Mesozoic age created a great sensation amongst the palaeontologists of the time, and it was not for more than twenty years afterwards that the opinion of the great French naturalist was generally accepted. Some contended that the fossil did not really belong to the slate, others that the strata in which they were found were not of the Mesozoic period; while others, again, urged that the jaws were those of a reptile, or even of a fish. All doubt having been set at rest with regard to these points, it will not be necessary to enter here in detail into the arguments used on either side. PreVost, in 1825, on his return from England, where he had carefully examined the specimen of Amphilestes now at York, and " le fameux Didelphe " in Buckland's collection, published the first detailed description and figure of this the type specimen of Amphitherium (25). He describes the teeth as having tricuspid crowns, and two distinct roots in alveoli, concluding that the fossil was Mammalian in confirmation of Cuvier. As to its relationship, Prevost considered that it was probably "un mammifere carnassier insectivore qui pouvaitoffrir quelque analogie avec les Didelphes, mais qui appartiendrait k un genre inconnu." Agassiz, in 1835, mentions the Stonesfield fossils in a short note (1). He considered that the remains were not sufficient to allow of a certain determination of their affinities, but drew attention to the resemblance of the teeth (especially those of Phascolotherium described below) to those of certain FOSSIL MAMMALIA FROM THE STONESFIELD SLATE. 411 seals possessing tricuspid molars. Owen mentions (20) that Agassiz proposed the name Amphigonus for Amphitherium, in the German translation of Buckland's Bridgewater Treatise (which I have not seen). Dr. Buckland, in 1836, gave a rough figure of this jaw, together with enlarged drawings of two of the teeth (6). Two years later M. de Blainville published his " Doutes sur le pretendu Didelphe de Stonesfield " (2), in which he tried to prove that the fossil in question, of which he reproduced Buck- land's figure, belonged to a reptile. In this paper he laid considerable stress on the fact that " une portion de machoire inferieure, rapporte'e de Stonesfield par M. Brochaut de Villiers et ses eleves MM. Elie de Beaumont et Dufre'noy, et qu'on avait supposee appartenir au mSme Didelphe," had been proved to be reptilian, and accepted as such even by Cuvier. Blain- ville mistook the mylohyoid groove,1 well marked in our specimen, for a suture indicating that the jaw was of a compound structure: a similar mistake was made in the case of the other jaws. He proposed the generic name Amphitherium, which has since been generally adopted. Buckland then took with him to Paris the type specimen of Amphitherium and the second fossil of the same species now in the Oxford Museum, which will be described below. He showed these to M. Valenciennes, who made a careful study of them, publishing a detailed account mainly confirming the results of Cuvier and Prevost, in which the name Thylaco- therium Prevostii is proposed (31). Unfortunately Blain- ville was not convinced, as he did not see the fossils, for he tells us that "le jour ou M. le docteur Roberton voulut bien m'inviter a passer la soiree chez lui avec M.

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