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Show 4 PROF. FLOWER ON THE SKULL OF A XIPHODON. [Jan. 4, better preserved than any other part of the body, that extinct forms of the group to which this one is allied have been characterized. The anterior portion of the skull has also been broken off close to the premaxillary suture, and consequently is wanting in the specimen. Before proceeding to the description of the skull, the question naturally arises-What inference can be drawn from the condition of the fossil and its matrix as to its probable origin ? Several experienced palaeontologists to whom it was shown while still partially imbedded, declared that they knew of no fossil remains in a corresponding condition ; and on comparing it with all the Mammalian specimens from every part of the world, contained in the British Museum, not one was found agreeing with it. It certainly approximates very nearly in most of its characters to the curious " box stones" of the Suffolk Crag, to which Mr. Ray Lankester directed attention in the ' Quarterly Journal of the Geological Society' for 1870 (p. 499), though less ferruginous in colour than they generally are. If this suggestion should prove to be correct.it will confirm the indication as to locality mentioned above. The "box stones" are evidently waterworn aggregations of sandstone, generally, though by no means invariably, surrounding some organic body, and are remnants of a broken-up formation of an earlier age than the Red Crag in which they are now found. They are considered by Mr. Lankester, from a comparison of the molluscous fossils found in them, to be of " Diestien " age, or approximately equivalent to the so-called "Black Crag" of Antwerp; but, as will be mentioned hereafter, the zoological characters of the present specimen indicate a much greater geological antiquity. The skull is that of a rather young animal, as shown by the still open suture between the basioccipital and the basisphenoid bones ; but (at least in the case of existing Ruminants) this sign of immaturity remains some time after all the permanent teeth are in place, as appears to have been the case in the present specimen. The cranium differs most notably from that of all existing species of Ruminants in the breadth and flatness of the frontal region between the orbits, the sudden contraction behind the orbits, and the large extent of the temporal fossae, which is increased by well-marked sagittal and occipital crests. Hyomoschus is that to which it comes nearest; indeed, if we could imagine a larger animal of the Traguline type (i. e. an animal with a more lengthened head, and greater surface for the implantation of teeth and for the attachment of muscles, without corresponding increase of size of the brain-cavity and orbits-the modifications, in fact, which always occur in lar°-er, as compared with smaller, members of a natural group), we should obtain a form closely resembling the present skull. Its special peculiarity would still be the flatness and width of the interorbital region above, in consequence of which the cavities of the orbits look directly outwards, instead of upwards and outwards as in Hyomoschus. The sides of the face in front of the orbits are flat, as in the Tra-gulidae and in many true Ruminants, without any sign of depression for a suborbital gland; but further forward, commencing just be- |