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Pachyderms with astragali of corresponding dimensions for the uniform and prominent convexity of the anterior articulation, for its continuation with the tibial trochlea, and for the single and uninterrupted calcaneal tract on the lower surface of the bone. The Proboscidians, which approach nearest the present fossil in the depressed form of the astragalus and the flattening of the calcaneal articulation, have that articulation divided into two surfaces by a deep and rough groove: the scaphoidal surface is likewise similarly divided from the tibial trochlea; and no Pachyderm has the upper articular surface of the astragalus traversed by an antero-posterior or longitudinal ridge, dividing it from an almost horizontal facet for the support of the end of the fibula..
"The peculiar form of the astragalus in the Ruminants, and especially the trochlear character of the anterior or scapho-cuboidal surface, place it beyond the pale of comparison. In all the placental Carnivora the scaphoidal convexity is pretty uniform, and occupies the anterior extremity of the astragalus, as in Man and Quadrumana, but it is more produced and supported on a longer neck, which is also more oblique than in the Quadrumana, where the astragalus already begins to recede, in this character, from the Human type. In the Seals the upper surface of the astragalus somewhat resembles the present fossil in the meeting of the tibial and fibular facets at an obtuse angle formed by a longitudinal rising, but the fibular surface is rather the wider of the two, and the tibial one is divided by a broad rough tract from the scaphoidal prominence; and in addition to this anterior production of the bone there is also another process from its posterior part, which, as Cuvier remarks, gives the astragalus of the Seal the aspect of a calcaneum. By some of the remarkable peculiarities which the astragalus presents in the Order Bruta, it approaches the Australian fossil under consideration; as in the Mylodon, for example, where the surface for the calcaneum is single and undivided. But in this great extinct leaf-eating quadruped the calcaneal facet is continued into the navicular facet, which, on the other hand, is separated by a rough tract from the tibial articulation, as in all the Edentata, recent and fossil. The latter character likewise distinguishes the astragalus of the Rodentia from the fossil astragalus under consideration.
"In the Ornithorhynchus the astragalus has a deep depression on its inner side for the reception of the incurved malleolus of the tibia, and in both the Ornithorhynchus and Echidna the tibial surface is more convex than in the present fossil.
"Amongst the existing Marsupialia, the astragalus in the largest herbivorous species, as the Kangaroos, offers very great differences from the present Australian fossil; the broad and shallow trochlea for the tibia is continued upon the inner side of the bone into a cavity which receives the internal malleolus; whilst the fibular facet is long and narrow, and situated almost vertically upon the outer side of the bone. The scaphoidal surface is unusually small, and convex only in the vertical direction; and is divided by a vertical ridge into two surfaces, the outer one being applied to the os calcis. The inferior and proper calcaneal articulation is divided into two small distinct surfaces, the outer one concave, the inner one concavo-convex.
"Amongst the gradatorial and pedimanous Marsupials, and herein more especially the Wombat, we at length find a form of astragalus which repeats most closely the characters of the extraordinary fossil under consideration: in the astragalus of the Wombat the fibular facet, of a subtriangular form, almost as broad as it is long, slightly slopes at a very open angle from the ridge which divides it from the tibial surface: this surface, gently concave from side to side, and more gently convex from behind forwards, repeats the more striking character of being directly continued by its inner and anterior angle with the large and transversely extended convexity for the os scaphoides. The calcaneal surface below is single and continued uninterruptedly from the back to the fore-part of the outer half of the under surface; and its outermost part is produced into an angle, which is received into a depression at the outer side of the upper articular surface of the calcaneum. Thus all the essential characters of the fossil are repeated in the astragalus of the Wombat. The differences are of minor import, but are sufficiently recognisable; thus, in the Wombat, the single calcaneal surface is directly continued into the cuboido-scaphoidal convexity, instead of being separated from it by a narrow rough tract, as in the fossil; the calcaneal surface is also narrower than in the fossil, and the outer angle is less produced: the division of the tibial trochlea for the inner malleolus is better defined in the Wombat, and the depression round which the continuous smooth surface between the tibial and scaphoid surfaces winds is less deep in the Wombat; the scaphoidal convexity is also less developed in the vertical direction in the Wombat.
"We thus find that the great fossil astragalus from Australia, viewed in reference to the general characters of that bone in the mammalian class, offers great and remarkable peculiarities; and we further find that these are exclusively, but most closely repeated in certain Australian genera of Marsupialia, and especially in the bulkiest of the existing vegetable feeders, which are not saltatorial. The inference can hardly be resisted, that the rest of the essential peculiarities of the marsupial organisation were likewise present in that still more bulky quadruped, of which the fossil under consideration once formed part.
"In the Kangaroo and the smaller leaping Marsupials the fibula is disproportionately slender and iminoveably attached or anchylosed to the tibia, reminding one of the Ruminant type of organisation; it sustains little if any of the superincumbent weight, and has no resting-place upon the astragalus, the outer malleolus being simply applied to the vertical outer surface of that bone. The broad and nearly horizontal surface in the present fossil clearly bespeaks the existence in the same animal of a fibula which must have almost equalled the tibia in size at its distal end, and have taken as large a share in the formation of the ankle-joint as it does in the Wombat: we may in like manner infer that the tibia and fibula were similarly connected together, and, coupling this with the ball-and-socket joint between the scaphoid and astragalus, we may conclude that the foot of the great extinct Marsupial possessed that degree of rotatory movement which, as enjoyed by the Wombat, is so closely analogous to the pronation and supination of the hand. We finally derive from the well-marked marsupial modifications of the present fossil astragalus, a corroboration of the inferences as to the former existence in Australia of a marsupial vegetablefeeder as large as the Rhinoceros, which have been deduced from the inflected angle and other characters of the jaw of the Diprotondon and the Nototherium, and from the fossil calcaneum, No. 1485, which has been referred to the Diprotodon. The present bone closely agrees in all its marsupial modifications with that calcaneum, but the single flat surface which articulated with the calcaneum is longer in proportion to its breadth than in No. 1485. From this circumstance, and the close agreement in colour and general condition which the present astragalus has with the jaw of the Nototherium, No. 1505, it more probably belongs to that genus; but for demonstration further discoveries will be required of parts of the skeleton so associated as to justify the inference that they had belonged to one individual.
"The present bone is from the alluvial or newer tertiary deposits in the bed of the Condamine River, west of Moreton Bay, Australia."
To these relics may be added a molar bone of the Mastodon, similar to the Mastidon angustinis, and provisionally called, by Professor Owen, Mastodon aicstralis, and which I bought from a native at Boree, the sheep station of Captain Ryan, through the agency of the overseer of that station. The native, in giving the bone, stated that similar ones, and larger still, might be got further in the interior; but that, owing to the hostility of a tribe, upon whose grounds the bones are to be found, it was impossible for him to venture in that time in search for more: as, however, he promised to exert himself at some future period, in order to supply me with some better specimens, I have left a reward with the man second in command of the station, and which was to be given to the native on his redeeming his pledge.
Should future enterprise lead travellers to that quarter, it will be deserving their while to push the inquiry farther, and add more evidence regarding the existence of the Mastodontoid animals in New Holland.
That vara avis, the Black Swan, which was discovered by Vlaming, as far back as 1697, may be looked upon as the precursor of those splendid collections with which Banks, Solander, Labillardiere, Menzies,