OCR Text |
Show 322 .DE. ST. GEOEGE MIVART ON THE SKELETON OF [Apr. 2, bounded by two ridges, the postaxial end of each of which projects beyond the postaxial margin of the lamella, and correspond with the two similar directed, superimposed, postaxial processes of more auterior cervical vertebrae. In P. erithacus the conditions are similar save that the neural spine (w)is not so well developed (though slightly more so than in the tenth vertebra), while the pleurapophysial lamella is quite as long antero-posteriorly as in that vertebra, though the styliform, more ventral, process (st) projecting postaxiad from its hinder margin is shorter than is that of the same vertebra. The neural arch is not so preeminently shortened antero-posteriorly as in the Lory. In both species the metapophyses are smaller than in the preceding vertebra. The twelfth vertebra of L. fiavopalliatus (figs. 5, 7, & 9) has the neural arch about as short antero-posteriorly as in the eleventh vertebra, while the pre- and postzygapophyses do not project more, and the interzygapophysial ridges (iz) are similarly developed. But the neural spine (n) is much more developed than in the eleventh vertebra; it is a high subquadrate process, highest preaxially. The hypapophysis (h) is of about the same size as in the eleventh vertebra, but the pleurapophysial lamella altogether makes default. There is a strong transverse process (diapophysis) (d) which serially corresponds with the ridge bounding dorsally the antero-posterior groove outside the pleurapophysial lamella of the eleventh vertebra-much enlarged. The ventral surface of the centrum is subquadrate in shape, the hypapophysis (h) depending from the hinder half of its antero-posterior middle. The ventral surface is bounded laterally by two ridges, the anterior ends of which project preaxiad as two processes one on either side of the preaxial central articular surface. The same two processes exist in the same parts (though to a less marked degree) in the tenth and eleventh vertebras. In P. erithacus (figs. 6, 8, & 10) this vertebra is similar save that (like the eleventh) it is not so much smaller than more preaxial cervical vertebras. In both species the metapophyses have here become obsolete. The thirteenth vertebra, in both, is very similar to its serial predecessor save that its neural spine (n) is more extended antero-posteriorly, that its hypapophysis is more pointed, that its zygapophyses are smaller, but with some reappearance of hyperapophyses (fip), its diapophysis (d) more antero-posteriorly wide and presenting a small concave articular surface on its ventral aspect, towards its postero- external angle, for the tuberculum (tp) of the first cervical rib, and another (cp) for its capitulum on the outer side of the centrum, a little behind the process which projects forwards outside the preaxial central articular surface. This process in P. erithacus has here (figs. 13, 14, & 15, pp. 325 & 326) begun to subdivide into two processes connected by a short ridge : one, more dorsal (x), on one side of the middle of the central articular surface; the other, more ventral (c), at the preaxial end of the ridge bounding laterally the ventral surface of the centrum. These latter processes may be regarded as catapophyses which here make their appearance |