300 MR. ^y. p. pycraft on the [Apr. 15, 



tinguishable. With the Falconidse, however, the case i.s diiferent ; 

 and it becomes a matter of nice discrimination to tell the coracoid 

 of the Falcones, or Polybori, from that of one of the Striges. The 

 Falcones may be distingviished by the absence of a supracoracoid 

 foramen ; but in the Polybori and Striges this foramen is present, 

 and almost identical in size and position. The coracoid of the 

 former can, indeed, scarcely be distinguished from that of the 

 latter. In the Owls apparently the base of the coracoid is com- 

 paratively deeply grooved to J&t the dorsal coracoid lip of the 

 sternum ; whilst in the Polybori, what corresponds to the dorsal 

 lip of the groove in the Owls is represented only by a low and 

 incomplete ridge ; lastly, in the Owls the linea aspera for the 

 coraco-brachialis posterior generally lies near the extreme lateral 

 border of the coiacoid shaft ; in the Polybori it lies nearer the 

 middle line. 



The scapula does not afford much matter for comment of any 

 systematic value. The acromial process in the Falconinse is 

 pneumatic and very broad, so much so as to project considerably 

 into the foramen triosseum, thereby considerably diminishing its 

 size. The acromion may be produced conspicuously forwards, 

 and this is particularly well seen in Neophron, where it con- 

 stitutes the greater part of the inner wall of \h.Q. foramen triosseum. 



The furcula in the Accipitres is remarkable for its great size 

 and strength. It is U-shaped, with the limbs set wide apart, 

 this latter feature being especially noticeable in the Buteonida?. 



In Serpentarius only does the furcula articulate with the 

 carina (text-fig. 33, p. 297), as in the Storks. Furthermore, as 

 we have ali-eady pointed ovit, Serpentarius agrees with the Storks 

 in that the furcula does not develop a facet for aiticulation with 

 the coracoid. It bears a hypocleideum of considerable size, directed 

 downwards, and presenting a keel-like border for articulation with 

 the carina. 



In the Cathartse only are the distal extremities pierced by 

 a pneumatic foramen. This is very laige and opens in the outer 

 aspect of each limb, immediately behind the acrocoiacoid. 



In the Falconidae the hypocleideum is vestigial or wanting. 

 In Microhierax the furcula is not perceptibly bent upon itself, as 

 in the larger members, nor are the limbs so wide apart. The 

 length of the limbs of the furcula in Microhierax is relatively 

 greater than in any other members of the order, since they equal 

 the length of the carina sterni. 



In the Buteonidse the limbs of the f urcvila, as we have already 

 remarked, are set widely apart, and are of great breadth at their 

 distal ends ; especially is this the case in such forms as Gypa'etus, 

 Haliaetus, and Aquila. The hypocleideum is vestigial or wanting. 

 It appears to be largest in Aquila and Pandion. In some 

 cases, Elanus for example, the proximal ends of the furcula are 

 very slender, and in this particular the furcula i-esembles that of 

 the Striges. The fvucula of the Accipitres is more unlike that 

 of the Stri^-es than is the case with the stern imi or coracoid, as 



