1903.] ON THE SYRINX OF THE ACCIPITRES. 157 



6. Oa the Modifications of Structure in the Syrinx of the 

 Accipitres, with Remarks upon other Points in the 

 Anatomy of that Group. By Frank E. Beddard, 

 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 t, viz. the following : — 



Thrasaetus, Falco, Herpetotheres, Biiteo, Milvus, Spizaetus, 

 Gypaetus, Uruhitinga, Hcdiaetus, Pandion, Tinimncidtts, Vidtur, 

 Milvago, Spilornis, Erytliropiis^ Morphnus, Relotarsics, Leioco- 

 23ternis, Circus, Aquila, Gircaetios, Dryotriorchis, Gyps, Hieraaidea, 

 Archibuteo, Geranoaeiios, JSfisaetus, Asturina, Folyborios, 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. ccmdicans t, F. feldeggi, 

 F. j)ereg7'imcs, F. biarmicus, F. lanarius. 



Wunderlich's description applies perfectly well to all of the 

 species enumerated above. The species studied by him were 

 F. jieregrinus and F. sttbbuteo. 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 Wundei-lich, " Beitrage zur vergleiclienden Anatomie und Entwicklungs- 

 geschichte des uiiteren Kelilkopfes der Vogel." Nova Acta Acad. C. Leop.-Carol. 

 JDeutscli. Ak. Naturf. Halle, xlviii. No. 1 (1884). 



t I do not, of course, include the American Vultures, SarcorJiamphus, Gypagus, 

 &c., amoug the Accipitres. 



X Or Hierofaloo candioans. 



