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Show 332 DR. ST. GEORGE MIVART ON THE SKELETON OF [Apr. 2, The first caudal vertebra has a small, quadrate, low, neural spine (n) and two prezygapophyses which extend but very slightly forwards, while the postzygapophyses are very small indeed. The transverse processes are simple, flattened above and below, and about as long as those of the last uro-sacral vertebra. The ventral surface of the centrum presents at its ventral margin two blunt hypapophysial processes, which abut against the postero-inferior margin of the sacrum. The second caudal vertebra is similar to the last except that the neural spine is not so quadrate (being highest preaxially), the prezygapophyses (pz) are slightly larger, the postzygapophyses more developed, while small hyperapophyses reappear upon them. The transverse processes (t) are slightly longer, while the two hypapophysial processes are clearly approximated and project slightly more preaxiad. The third caudal vertebra has again the same characters carried slightly further, while the hypapophysis has become single and projects slightly forward beneath, and applied to, the ventral surface of the second caudal. The fourth caudal vertebra has its neural spine and prezygapophyses inclined strongly preaxiad, the hyperapophyses slightly larger and the transverse processes slightly longer (both are here at their maximum in the caudal region), while the hypapophysis is a little more developed, ventrally grooved antero-posteriorly, and tending to bifurcate at the apex, and developed, as before, from the preaxial end of the centrum. The fifth caudal vertebra has its transverse processes slightly shorter, the neural spine less inclined preaxiad, and hyperapophyses much smaller and more preaxially placed. The hypapophysis is long, situated at the preaxial margin of the centrum, and bifurcates distally. The sixth caudal vertebra has all its parts and processes diminished save the hypapophysis (h), which is somewhat longer and stouter, still less inclined preaxiad, but still distally bifurcating into two lateral processes diverging slightly more than those of the fifth caudal vertebra. THE PYGOSTYLE. The pygostyle in L. fiavopalliatus (py, fig. 12, p. 324) is a laterally much compressed subquadrate plate of bone with anterior, superior, and posterior margins, while inferiorly it carries on, as it were, the series of caudal vertebrae. At its preaxial end below are minute transverse processes and prezygapophyses, which latter adjoin the corresponding parts of the last caudal vertebra. From its ventral surface a process depends which is in series with the hypapophyses in front. The preaxial margin of the plate is strongly concave, the postaxial margin slightly so. The former margin is entirely thin, but the posterior one is medianly thin but thickened, though flattened, |