OCR Text |
Show 1905.] OSTEOLOGY OF THE EUR YLjEMID/E. 45 components of the synsacral vertebrae are shorter, so that the diapophyses of the first precaudal are overlapped by the hinder ends of the innominate. Well-marked intercentra appear on caudals 5-7, in each of the three genera here described. v. T he R ibs. The cervical ribs extend from the 4th to the 12th vertebrae. The 1st and 2nd, 10th and 12th, are represented by little more than broad pleurapophysial lamellae; in the remaining vertebrae, however, these lamellae are narrow and band-like, and the ribs slender and styliform, extending the whole length of the centrum. There are 3 cervico-thoracic ribs. The first is reduced, only the capitulum and tuberculum remaining connected by a common base. The second is long, but bears no uncinate ; the third bears a short sternal segment, which, however, does not reach the sternum. There are 5 thoracic ribs, of which 4 only reach the sternum. The uncinates are long and extend backwards to reach the 3rd rib from their base of attachment. In Corydon the sternal segment of the 5th rib articulates by a special facet with the sternal segment of the rib next in front. vi. T he Sternum and Siioulder-girdle. (Text-figs. 13, 14, pp. 46, 47.) The sternum of the Eurylsemidae is typically Passeriform, and presents no very close resemblances to that of any other group. In some features it recalls that of the Cuckoos, in others of the Caprimulgi, but these are not of a nature likely to cause difficulty in confounding the sterna of either of these groups with Passerine sterna. In the Eurylaemidao the corpus sterni is short and broad-the breadth neai-ly equal to the length. The posterior lateral processes are long, extending forwards to a point corresponding to a transverse line through the middle of the corpus sterni; the free ends of these processes are spatulate. The metasternum has its free border squarely truncate, so as to form a continuous line with the free ends of the posterior lateral processes; broken only by the notch enclosed by this process. The anterior lateral processes in Calyptomena have their free ends truncated and curved slightly backwards. In Corydon these processes are long, pointed and directed forwards. Cymbirhynchus is intermediate in this respect, the process being long, truncate, and directed forwards. The articular surfaces for the sternal ribs are confined entirely to these processes. There is no spina interna. The spina externa shows only the faintest indication of the bifurcate free end which prevails among the Passeriformes (text-fig. 13, s.e.). In Cymbirhynchus and Corydon this spine is triangular in section ; in Calyptomena it |