. Bulletin - American Museum of Natural History. Natural history; Science. 1895-] Wortman, Osteology of Agriochoerus. 149. then have the highly characteristic dorso-lumbar formula for all the known Artiodactyla. The atlas presents the same general outline as that seen in the Artiodactyla. The articular cavities for the condyles of the skull are deep and spacious and are overhung by the anterior superior part of the arch. In Oreodon and all the recent genera this part of the arch is interrupted by a wide notch which shortens its fore and aft extent. In Agriochoerus this notch is very narrow, an
. Bulletin - American Museum of Natural History. Natural history; Science. 1895-] Wortman, Osteology of Agriochoerus. 149. then have the highly characteristic dorso-lumbar formula for all the known Artiodactyla. The atlas presents the same general outline as that seen in the Artiodactyla. The articular cavities for the condyles of the skull are deep and spacious and are overhung by the anterior superior part of the arch. In Oreodon and all the recent genera this part of the arch is interrupted by a wide notch which shortens its fore and aft extent. In Agriochoerus this notch is very narrow, and is continued upwards and backwards as a deep groove which sepa- rates the spine into two low indistinct tubercles. The transverse processes are well extended laterally, somewhat broader in front than in Oreodon, and project backwards further behind the facets for the axis. They are perforated by moderate sized foramina for the passage of the vertebral artery, which does not appear to be the case in any specimen of Oreodon which I have examined. Anteriorly, the foramen for the exit of the suboccipital nerve is large and conspicuous, while the inferior tubercle is small. The facets for the axis are more transverse, and not so oblique as in Oreodon, resembling more nearly the sheep or deer in this respect. The axis, as described by Scott,1 differs from that of Oreodon. This is especially to be seen in the character of the spine. In Agriochotrus it is unusually high and prolonged in front, so as to overhang the odontoid slightly, while behind it is not so produced, reaching no further than the extremity of the posterior zygapophyses. In Oreodon the spine ,.â >â '" is much lower, but little produced in front, but greatly thickened and extended posteriorly. The odontoid, as already well known, is intermediate between the peg-like form of the pig and the Fig. 3. side view , ,, 11,- i-i r ^ t ⢠1 r x of axis of Agriochce- hollow half-cylinder of the higher forms. In rus
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