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Show 1903.] OSTEOLOGY OF THE CUCULIFORMES. 273 The most complete synsacrum is that of Coua, and is made up as follows:-1 thoracic, 3 lumbar, 3 lumbo-sacral, 2 sacral, and 4 caudal, making 13 in all. Rhopodytes seems to possess the most reduced synsacrum: the number of thoracic, lumbar, and sacral is the same as in Coua, but the lumbo-sacrals are reduced to 1 and the caudal to 2 : making therefore a total of 9 vertebrae as against 13 in Coua. Crotophaga and Geococcyx each have 11 vertebrae in this region. In the former, the reduction is from the lumbo-sacrals, which are only represented by a single vertebra; in the latter there are 2 lumbo-sacrals, but only 3 caudals. In other genera, the number of vertebra? appears constantly to be 12 , composed as follows:-1 thoracic, 4 lumbar, 1 lumbo-sacral, 2 sacral, and 4 caudal. In no case can distinct sacral vertebra? be made out. The synsacrum of Rhamphococcyx is remarka ble in that the single lumbosacral vertebra bears a pair of exceptionally strong ventri-lateral processes. Vestiges of these appear in Scythrops, Coua, and Taccocoua. In Centropus the third and fourth pairs of ventri-lateral processes are apparently undergoing coalescence. In some skeletons this fusion is complete; in others traces, more or less marked, of the original buttresses still remain. The last two caudal vertebrae combine to form a well-marked planum anale. There are 6 or 7 post-synsacrals-free caudal vertebrae. Of these the 4th and 6tli bear pointed intercentra, which, however, are completely fused with their respective centra. The total number of vertebrae reaches its highest in Coua with 37. The vertebral column of the Musophagi is scarcely distinguishable from that of the Cuculi. The cervical vertebrae closely recall those of Cuculus. They may be distinguished therefrom, however, apart from their greater size, in that the 3rd and 4th both send backwards a bar from the meta-to the liyperapophysis, and in that the 7th and 8tli send back a similar bar from the same region to the middle of the neural arch. There are only two cervico-thoracics. The vertebra corresponding to the third cervico-thoracic of certain Cuckoos, e. g. Scythrops, becomes in the Musophagi thoracic, being joined to the sternum by a sternal rib. The thoracic vertebra? differ from those of the Cuckoos, in that the transverse processes send backwards from their postero-external angles a long bony spike to overlap the transverse process of the vertebra next behind it. These connecting-rods are either wanting or very feebly developed in the Cuckoos, e. g. Scythrops. The cervical vertebrae are 12 in number, the cervico-thoracic 2, thoracic 6, the last being fused with the synsacrum. The synsacrum contains 13 vertebrae, and is made up as follows: thoracic 1, lumbar 3, lumbo-sacral 3, sacral 2, caudal 4. 18* |
