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Show 1903.] SYRINX OF T H E ACCIPITRES. 163 the tongue is covered by several rows of backwardly directed spines, in addition to the row of larger spines along the posterior edge of that organ. On the other hand, in one or more species of the genera Milvus, Circus, Leucopternis, Spizaetus, Archibuteo, Dryotriorchis, Morphnus, Asturina, Gypohierax (text-fig. 20, p. 162), and Urubitinga, the tongue has only the posterior row of spines. Vultur is peculiar in possessing, in addition to the posterior row of spines, a lateral row on each side along the thick edge of the tongue. There are traces of them in Aquila, Nisaetus, and Gypaetus, and perhaps in some other forms. Conclusions. The principal conclusion of the foregoing enumeration of facts concerns the classification of the Accipitres. It is perfectly plain, as I think, that the structure of the syrinx permits of, or indeed necessitates, the division of the Accipitres into two families or subfamilies, which may be termed FalconidaB and Buteonida? (or Falconina? and Buteoninse). It is important to notice that in insisting upon such a division, I a m in complete agreement with Dr. Suschkin * and Mr. Pycraft f, both of whom have lately attempted a classification of the group on Osteological grounds. This satisfactory result shows the value of the form of the syrinx in this group, as has been shown with the syrinx of other groups, such as the Cuckoos. As to further subdivisions of these two main divisions, the facts at m y disposal do not allow of any expression of opinion. Nor do I venture to lay too much stress upon the apparent agreement in the structure of the tongue with the facts derived from a study of the syrinx and bones, since the material at m y disposal was not very abundant. The next most important point which I have been able to ascertain is the development of a bronchial syrinx in Dryotriorchis. This makes it more plain than ever that it is dangerous to compare birds belonging to different groups which happen to possess the bronchial form of the syrinx; for while it is possible on other grounds that the Goatsuckers and Owls, both of which contain genera which have bronchial syringes, are allied, it is not probable that they, the Cuckoos, and the Hawks are cdl nearly akin. It seems to m e to be a form of syrinx which has been acquired several times and independently. * Zool. Anz. vols. xxii. & xxiii. 1899 & 1900. f P. Z. S. 1902, vol. i. p. 315. 11* |