196 AVES (the bird) 



(2) The two clavicles are ankylosed together at their 



ventral ends, forming the 'Vish-bone." 



(3) How is this end joined to the keel of the sternum? 



(4) To what do the proximal ends articulate? 



5. The Sternum, or Breast-bone, is the somewhat triangular 

 bone below the body-cavit3^ 



(1) What is its shape next to the viscera? Why? 



(2) What is the purpose of the keel which projects on its 



ventral side? 



(3) What bones are attached to the sternum? 



6. The Wings. 



(1) Compare the bones of the wing with those of the arm 



of man. 



(2) Name and describe the bones of the proximal and distal 



portions. 



(3) In what direction from its proximal attachment does 



each of these portions of the wing extend? 



(4) The distal portion of the wing is made up of the bones 



of the carpus, metacarpus, and phalanges, which are 

 much modified, fused, degenerate, or lacking. 



(5) Compare your specimen with some good figure of it 



and find two free carpal bones, the radial and the 

 ulnar, the carpometacarpus, a long curved bone 

 formed by the fusion of the distal carpal bones with 

 the first three metacarpals, and the first three digits, 

 the third consisting of but a single bone. 



7. The Pelvic Girdle consists of a right and left innominate 

 bone, each of which is formed by the fusion of the ilium, ischium, 

 and pubis, at the union of which is the acetabulum, or depression 

 for the head of the femur. See if you can distinguish these 

 bones. 



8. The Legs. 



(1) The femur, or thigh bone, fits into the acetabulum 



at its upper end. 



(a) What is its length? 



(b) In what direction does it extend from its upper at- 



tachment? 



(2) The middle portion of the leg is composed of two bones; 



the tibiotarsus or long bone, formed by the fusion 



