306 STERNA OF THE (..U.I. IMP. K. 



extending, in fact, fully more than three-fourths of 

 the entire length of the sternum; and the two lateral 

 processes, though united by cartilaginous membranes 

 to each other and to the central bone, having more 

 the appearance of a forked sternal rib than of portions 

 of the sternum as a continuous bone. The keel is 

 considerably developed, especially in the anterior 

 part, but lower toward the rear, though there it still 

 affords some stiffness to the middle portion of the 

 sternum. The anterior part of the sternum terminates 

 in a triangular process, which is notched at the edges 

 to receive the coracoid bones, and the lateral processes 

 extend forwards nearly as far as the triangular one 

 in the centre. The coracoids are rather strong, flat- 

 tened on their anterior edges, and with an angular 

 ridge backwards. The clavicle is a semi-ellipse, 

 more elongated, and with the branches much more 

 straight, feeble, and flexible, than in the pigeons. 

 It has always a process at the union of the two 

 branches, often of considerable size, and directed 

 toward the anterior part of the keel to which it is 

 united. The shoulder bones are rather large, broader 

 in the middle than toward the extremities, and a little 

 bent. 



The whole structure of this sternal apparatus shows 

 that its strength lies much more in the vertical plane 

 than in the horizontal, and consequently that it is 

 better adapted for supporting the body of the bird, 

 while walking or running, than for giving steadiness 

 to the wing in flight. The coracoid and the clavicle 

 stand upon the sternum like two sides of a triangle, 

 of which the anterior parts of that bone and its keel 

 form the third side or base, and thus the shoulder- 

 joint is kept at the same vertical distance from the 

 sternum. The enlargement of the blade-bone, too, 



