| OCR Text |
1895.] LOEIUS F L A V O P A L L I A T U S A N D PSITTACUS EBITHACUS. 331 THE SACEAL VEETEBE^E. The solid mass formed by these vertebrae (figs. 18 & 19) is longer than broad and narrows gently backwards. Its ventral surface is slightly grooved antero-posteriorly in its middle. It develops no parapophysial transverse processes, and so a large long fossa (If) lies on either side of it, roofed by the ilium and bounded in front by the parapophysial transverse process of the last lumbo-sacral vertebra and behind by the transverse process of the first uro-sacral vertebra. Rudiments of diapophysial portions of transverse processes appear to coalesce with the ventral surface of the ilium of this region. THE UEO-SACEAL VERTEBE^E. These vertebrae (figs. 16, 18, & 19) continue on postaxially the sacral mass, narrowing gradually as they proceed. It develops a series of parapophysial transverse processes (pi), six at least on each side, which extend outwards, backwards, and slightly upwards, anchylosing with the ischium at their apices. They anchylose with it also for more or less, or for the whole, of their extent in P. erithacus. The diapophysial elements of the transverse processes are widely extended antero-posteriorly, and unite so as to form the dorsal sacral escutcheon (es), which is a continuous sheet of bone save for the sacral foramina, which indicate the limits of the diapophysial transverse processes-interposed between the hinder halves of the two ilia and the two ischia. In L. fiavopalliatus each of the transverse processes on either side of the first uro-sacral vertebra is quite separate from the ischium above it till close to the apex of the transverse process, when it anchyloses therewith. Its dorsal sacral escutcheon also is almost entirely postaxial to the acetabula instead of extending in front of them as in P. erithacus, and presents on either side a marked antero-posterior groove (ges), widening backwards from its apex, which is placed in a line nearly coincident with the hinder margin of the acetabulum. These two grooves are separated by a strongly-marked antero-posteriorly extending ridge (narrowing postaxiad), which is only faintly indicated in P. erithacus. THE CAUDAL VEBTEBB-S;. There are six caudal vertebrae in L. fiavopalliatus (fig. 12, p. 324), with variously developed neural spines, zygapophyses, transverse processes (t), and hypapophyses. The first three caudal vertebrae have transverse processes (f) which are simple, flattened above and below, and slightly increase in length from the first to the fourth caudal vertebra. Those of the first are about as long as those of the last uro-sacral vertebra. The prezygapophyses (pz) of the first of these vertebrae extend but very slightly forward, those of the other two extend preaxiad more and more, |
