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Show 1876.] PROF. FLOWER ON THE SKULL OF A XIPHODON. 5 hind the large infraorbital foramen, is a wide and deep oval depression, extending over the whole of the region above the premolar teeth. Indications only of such a depression are seen in the Tragu-lidae. There is no vacuity at the point of junction between the nasals, maxillae, lachrymals and frontals, as in so many Cervidae and Antelopes, and as is slightly indicated in Hyomoschus, though not in Tragulus. The sutures bounding the lachrymal bone, and between the maxilla and malar, are beautifully marked by deeply indented and wavy lines; but the premaxillary suture cannot be distinguished, being probably situated anteriorly to the point of fracture of the skull. The supraorbital foramina are not very large, and are placed in depressions rather nearer the middle line than the margin of the orbit, on a level with the anterior angle of that cavity ; and, as iu many existing Artiodactyles, a groove is continued forwards from them. The posterior margin of the orbits, if, as is probable, they were originally complete, have been broken away, as has the entire zygomatic arch. Turning to the base of the skull, the occipital condyles are lost; but the greater part of the basioccipital, with its pair of pr minent tubercles, remains. On each side of this the oval form of the bases of the large auditory bullae can be distinctly made out, though they have been worn level to the rest of the surface of the skull. Their interior, however, can be seen to be filled with a fine network of cancellar tissue-a character common to the Suidae, Tragulidae, and Camelidse, and absent in nearly all the true Ruminants. On the lower surface of the skull, as well as above, the elongation of the middle region is a conspicuous feature. The hinder margin of the palate is produced backwards to the extent of fully three quarters of an inch beyond the notches on each side ; but as its edge has been broken off, it is impossible to describe its true form. Between the teeth the surface is long, narrow, and depressed along the middle line. There is no sign, even at the anterior fractured edge, of the incisive foramina, which must consequently have been small; but there is a conspicuous foramen opening forwards near the outer edge of the palate opposite the second premolar tooth, and placed rather more posteriorly on the left than on the right side. The alveoli, in most of which broken roots of teeth remain, form a continuous series along each side of the palate, as far forward as the line of fracture. Posteriorly they have been so much injured that their form and number cannot be made out with perfect certainty ; but they appear to indicate teeth of the following character. Beginning at the hinder end of the series, there are three molars, with four roots, wider transversely than from before backwards. The most anterior of the three must have been considerably smaller than the other two, which appear to have been nearly equal in size. In front of the molars there are seven roots, rounded or transversely elongated, placed in a single line, and nearly equidistant, indicating a series of compressed teeth, each with an anterior and a |