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Show 272 MR. W. T. PYCRAFT ON THE [Mar. 17, outwards and upwards into a pair of pointed hyperapophyses. The neural arches of the vertebra?, from the third to the fifth inclusive, are very broad, and with or without spines. From the third to the sixth or seventh vertebra? large metapophyses occur, those of the fourth, fifth, and sixth being especially large, projecting like buttresses from the base of the anterior zygapophyses. The metapophyses of the third vertebra send back each a slender bar of bone to join the liyperapopliysis. A similar bar of bone occurs also from the fourth to the seventh vertebra?, but instead of joining the hyperapophysis, fuses with the antero-lateral angle of the shield-shaped expansion formed by the neural arch. The succeeding cervicals do not afford any particularly well-marked characters in so far as this region is concerned. The anterior cervicals of Scythrops and Cuculus (1 to 7) differ from those of the Cuckoos just described in that they are relatively slightly longer antero-posteriorly, that the bony bar from the metapophysis to the hyperapophysis occurs only in the 3rd vertebra, and in that the shield-like expansion of the neural arches is very feebly developed. Short neural spines occur in the 2nd, 3rd, and 4th vertebra?. The 2nd, 3rd, and 4th vertebrae bear liypapophyses; from the 5tli to the 10th these are replaced by catapophyses, which from the lltli vertebra backwards to the last cervico-thoracic are replaced again by liypapophyses. The cervico-thoracic vertebrae are peculiar in that they bear more or less well-developed catapophyses in addition to the median hypapophysis. The catapophyses never coalesce to form a carotid canal. The cervico-thoracic vertebrae may be two or three in number. The number of the true cervicals varies, being either 11 or 12. The thoracic vertebrae are free. The 1st or 1st to 3rd, as in Eudynamys and Coua for example, bear liypapophyses. Pneumatic foramina pierce the centra of the vertebra beneath the transverse processes. The neural spines of these vertebrae gradually increase in height from before backwards, and are more or less quadrate in form. Coua, however, appears to form an exception to this rule, the spine of the 1st thoracic being almost obsolete, and thus agreeing with the cervico-thoracic vertebrae; whilst the spines of the 2nd, 3rd, and 4tli vertebrae are, relatively, as high as in other Cuckoos. The last two cervico-thoracic (2nd and 3rd) have apparently only recently become separated from the thoracic series, inasmuch as the vertebral segments of their respective ribs have undergone no reduction in length. The ribs of the third pair still retain their uncinate processes. Only one thoracic vertebra, in the Cuculi, enters into the synsacrum. The synsacrum includes from 10 to 13 vertebrae. The smaller number appears to have been due to the reduction, possibly by excalation, of the lumbar or lumbo-sacral vertebrae, or of caudal vertebrae, as in Geococcyx. |