1902.] 



OSTEOLOGY OF THE FALCONIFORMES. 



297 



is present in all the Accipitres. In the Falcons only does the 

 anterior angle of the carina project forwards as far as the level 

 of the spina externa. Again, whilst in nearly all the other 

 Accipitres the sternal ribs attach themselves along the whole 

 outer border of the anterior lateral processes, in the Falcons 

 the distal third is ribless. In the larger Falcons the sternal 

 plate is fenestrated posteriorly, but in the small forms — Melierax, 

 Poliohierax, Microhierax — it is notched. In Falcons, the coiacoid 



Text-fiff. 33. 



Left lateral aspect of the Sternum and Slioukler-girdle of Serpetifarhis serjaenfarius, 

 showing the articulation of the furcula with the carina. 



ac. = acrocoracoid. 

 cor. = coraco'd. 

 cs. = corpus sterni. 

 JEf. = hypocleideum. 



car. = carma. 

 _f. = furcula. 



sr. = sternal rib. 



grooves overlap one another, and the spina externa is relatively 

 long and pointed. The articular surfaces for the sternal ribs 

 extend backwards as far as the middle of the sternal plate. 



The sternum of the Polyhorince resembles that of the Falcons, 

 but the spina interna is shelf-like instead of spiny, and the 

 anterior border of the keel does not project so far forward. 



In the Buteonidfe (Suschkin) the spina interna is not developed. 

 The spina externa varies much in size. Generally, it nay be 

 described as a short stoiit tubercle ; but in Accipiter it becomes a 



Proo. Zool. Soc— 1902. Yol. I. No. XX. 2U 



