. The Quarterly journal of the Geological Society of London. EVANSI. 717 bone is deeply concave from side to side, nearly flat from withinoutward, with the articular surface directed outward and downwardso as to meet the inferior external surface in a rounded border. Itsantero-posterior extent in the middle is 1^ inch, but becomes lesslaterally. The line in which it joins the atlas is concave, but is ina vertical plane. On each side the wedge bone terminates superiorly in a flattenedtriangular surface, to which were attached the bases of the neural-arch elements. The neural-arch bones are not
. The Quarterly journal of the Geological Society of London. EVANSI. 717 bone is deeply concave from side to side, nearly flat from withinoutward, with the articular surface directed outward and downwardso as to meet the inferior external surface in a rounded border. Itsantero-posterior extent in the middle is 1^ inch, but becomes lesslaterally. The line in which it joins the atlas is concave, but is ina vertical plane. On each side the wedge bone terminates superiorly in a flattenedtriangular surface, to which were attached the bases of the neural-arch elements. The neural-arch bones are not preserved. Eachhad a broad union with the atlas, which widens laterally (b, fig. 2)from | inch below to the entire width of the centrum surfaces look obliquely outward, forward, and upward, andtherefore have a tendency to converge upward and forward, wherethey are -Z- inch apart at the anterior margin of the neural canal (c?,fig. 1). Fig. 1.—Anterior aspect Fig. 2.—Left side view of Atlas of Atlas, | nat. size. and , ^ nat. L e Articular face of centrum. c. Surface from which the neural d. arch has come away. e. Subvertebral of neural for rib. The neural surface is 1^ inch wide posteriorly, slightly concavefrom side to side, and has vascular foramina on its lateral margins—three conspicuous foramina on the left side, and smaller foraminaon the right side. The anterior face of the centrum (a) is necessarily small and four-sided ; but it has a subtriangular aspect, owing to the shortness of thesuperior margin of the neural canal and the width of the wedge boneforming its curved base. It is concave and deepest in the centre,though not much impressed. The extreme width of the centrum, just behind the neurapophysialfacets, is rather less than 3| inches. The lateral non-articularsurfaces of the centrum (fig. 2) are below theso points ; they aresmall and subtriangular, about -J inch from side to side, and 1|inch fro
Size: 2228px × 1122px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1840, bookidquarte, booksubjectgeology
