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Show 1903.] ON THE SYRINX OF THE ACCIPITRES. 157 6. On the Modifications of Structure in the Syrinx of the Accipitres, with Remarks upon other Points in the Anatomy of that Group. By F R A N K E. B E D D A R D, M.A., F.R.S., Prosector to the Society. [Received June 16, 1903.] (Text-figures 16-20.) Although a considerable number of species of Accipitres have provided material for the study of the avian syrinx*, I am not aware of the existence of any general survey of the structure of the windpipe in this group of birds which is so extensive as that which I am able to lay before the Society. My material has been gradually amassed by my predecessors in the office of Prosector to the Society and by myself, and represents a large series of Accipitrine genera f, viz. the following :- Thrasaetus, Falco, Herpetotheres, Buteo, Milvus, Spizaetus, Gypaetus, Urubitinga, Haliaetus, Pandion, Tinnunculus, Vultur, Milvago, Spilornis, Erythropus, Morphnus, Helotarsits, Leuco-pternis, Circus, Aquila, Circaetus, Bryotriorchis, Gyps, Hieracidea, Archibuteo, Geranoaetus, Nisaetus, Asturina, Polyborus, Poly-boroides, and Gypohierax : in all 31 genera, of many of which I have examined several species. I shall not, however, describe all of these types in detail, inasmuch as there are very close resemblances between many of them. My purpose is rather to establish the importance of the syrinx as confirmatory of other opinions upon the Classification of this Group. Genus FALCO. Of this genus I have examined syringes of the following seven species, viz.:-F. sacer, F. cesalon, F. candicans +, F. feldeggi, F. peregrinus, F. biarmicus, F. lanarius. Wunderlich's description applies perfectly well to all of the species enumerated above. The species studied by him were F. peregrinus and F. subbuteo. The salient feature of the syrinx is the large extent of the membrana tympaniformis externa, due to the concave lower border of the first bronchial ring and the concave upper border of the second bronchial semiring. This characteristic feature of the syrinx of Falco is more marked in F. sacer than in any other species. The intrinsic muscles are attached to a specially thickened and apparently cartilaginous bar-like tract of the membrana tympaniformis externa, which varies somewhat in stoutness and exact position. The complete- * See Wunderlich, " Beitrage zur vergleichenden Anatomie und Entwicklungs-o- eschichte des uuteren Kehlkopfes der Vogel." Nova Acta Acad. C. Leop.-Carol. beutsch. Ak. Naturf. Halle, xlviii. No. 1 (1884). f I do not, of course, include the American Vultures, Sarcorhamphus, Gypagus, &c, among the Accipitres. J Or Hierofaleo candicans. |