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Show 468 DR. J. MURIE ON SAIGA TARTARICA. [Julie 9, praemaxillae fall short of the nasals ; but in all these Antelopes, the latter bones abut to a considerable extent against the maxillae. In the limited section of Caprine Antelopes of Gray, Ovine Antelopes of Turner, Capricornis, Nemorheedus and Budorcas, the nasals are but of moderate length, the premaxillaries do not reach them, and tbe maxillae barely coalesce nasally. In some Oxen, Bubalus and Bibos to wit, and also in the aberrant Sheep Ovibos, the premaxillary stunting is marked, but the relation of nasals to maxilla is quite different from the peculiar one in Saiga. The complementary changed relations of the facial bones of Saiga, and especially the increased height but antero-posterior shortening of the lachrymals, differ quite from the modern Ruminant skull, where, as a rule, the horizontal is greater than the upright breadth in the latter bone. Besides these major differences, tbe Saiga recedes from supposed alliance with Gazella and Cervicapra in absence of suborbital fissure-though, exceptionally, the Chiru agrees with it in wanting a fissure ; but it differs from each in the very slight impress of suborbital fossae. Indeed, within certain limits, it may be said that tbe suborbital fossa of Saiga, though wider, has more the shallow roundish character of that of Sheep than Antelopes. The opposite of this remark applies to the masseteric ridge, as the higher position of the Anti-lopine orbit gives increased length of ridge, as in the Saiga. Goats, with their elongate fissure, and Deer, with a most extensive wide one, and very deep lachrymal fossa, are remote in facial construction from the type in question. The group which Dr. Gray designates " Antelopes of the field," including Antilope, Gazella, Tetracerus, Cephalophus, and other genera, and the same author's " Antelopes of the Desert," Alcephalus &c, have all large, more or less inflated tympanic bullae. It is to the former of these groups that the Saiga has been assigned ; and the development of its ossa tympani in a fair degree shows derivation from it, or unity of stock. In the Society's specimen the bullae are rather more inflated than in the skull at the Hunterian Museum ; and both are fuller and not quite so laterally compressed as in the so-called Cervine Antelopes, fEgocerus, &c. The Caprine Antelopes are still further removed, judged of by this single character ; for in them the tympanies are moderate and compressed. The triangular, horizontally elongated and ridged tympanic bones of the Goats and the Deer even more markedly deviate. In Sheep, as Turner observes, there is a small auditory bulla; but I find in Ovis vignei that the bulla is not only of moderate, but indeed of fair size, and quite equal in relative magnitude to that of the Saiga, its shape rather more elongated, but not unlike the latter. The centre point of the skull, the basioccipital bone, forms a good diagnostic mark between the Antelope groups, especially when taken in conjunction with the tympanic elements and disposition of the facial bones. Usually the basiocciput is longish and narrow, high, convex, and mesially grooved antero-posteriorly. Continuous |