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Show 316 DR. ST. GEORGE MIVART ON THE SKELETON OF [Apr. 2, spine (n) is quadrate and directed almost exclusively dorsad, instead of being obtusely pointed and directed postaxiad as in P. erithacus. The postzygapophyses are almost entirely devoid of hyperapo-physes. There are small and flattened ones as in P. erithacus. The postaxial margin of the pleurapophysial lamella also shows two superimposed postaxiad processes, the more ventral of which is continuous with the ridge bounding externally the antero-posterior groove on the ventral surface of the parapophysial lamella. The prezygapophysis bears a small prominence on its outer surface, which becomes noteworthy in the next vertebra. Fig. 6. Lateral aspect of 3rd to 12th vertebrae of Psittacus erithacus. c. Oatapophysis. d. Diapophysis. /. Foramen. h. Hypapophysis. hp. Hyperapophysis. m. Metapophysis. n. Neural spine. pi. Pleurapophysial lamella. ptz. Postzygapophysis. pz. Prezygapophysis. st. Styliform process. The fifth vertebra has the postzygapophyses much lengthened in both species, but especially in L. fiavopalliatus, in which also the neural spine is smaller and more quadrate in outline. It arises some distance behind the preaxial end of the neural arch. In both species the hyperapophyses (hp) have the form of two small ridges diverging postaxiad from the hinder end of the base of the neural spine-more marked in L. fiavopalliatus, in which species the hypapophysis is small and extends preaxiad from just behind and below the anterior central articular surface. The ventral margin of the vertebra is much more antero-posteriorly concave than in P. erithacus. The ventral antero-posterior groove on the parapophysial lamella is almost obsolete, but the, here expanded, outer surface of the pleurapophysial lamella shows, above and preaxially, a rough prominent process (metapophysis) on the outer surface of the prezygapophysis (there is a rudiment of the metapophysis in the fourth vertebra), and, more ventrally, a very small process near the antero-inferior angle of the lamella on either side. These are catapophyses * (c). The ventral margin of that lamella gives rise at its postaxial end to a short styliform pleurapophysial process (st), which seems to answer to the lower of the two superimposed processes of the third vertebra. The higher of the two is much extended and joins the under surface of 1 See op. cit. p. 401, |
