194 AVEs (the bird) 



1. The Skull. 



(1) Note the quadrate bone, to which the lower jaw is 



attached. 



(2) Note the large posterior opening, the occipital foramen, 



in the base of the skull. 



(3) Are there one or two little knob-like projections 



(occipital condyles) which fit into the atlas, or first 

 cervical vertebra? 



(4) Are the bones of the skull compact and heavy, or 



spongy and light? 



(5) Are the bones completely ankylosed together, or can 



you distinguish the sutures between them? The 

 sutures are less plainly visible in an old bird than in 

 a young one. 



2. The Vertebrae. 



(1) Notice how the first and second vertebrae fit together. 



(2) How many vertebrae are there between the skull and 



the first pair of ribs articulating with the sternum? 



(3) How many vertebrae bear ribs? 



(4) The Sacrum. Fourteen or fifteen vertebrae are fused 



together to form the sacrum which supports the 

 pelvic girdle. Note the openings through which the 

 spinal nerves pass. 



(5) How many free caudal vertebrae do you find? 



(6) Note the terminal bone, the pygostyle, formed from 



the fusing together of several vertebrae. 



3. The Ribs. 



(1) How many ribs do not articulate with the sternum? 



(2) How many ribs articulate with the sternum? 



(a) In what direction does the vertebral, or dorsal, por- 



tion of these ribs extend? 



(b) In what direction does the ventral or sternal portion 



extend? 



(c) How do they meet? At an angle or in a straight line? 



(d) What is the advantage of this arrangement? 



4. The Pectoral, or Shoulder Girdle. 



(1) On each side, it consists of a scapula, or shoulder-blade, 

 a stout coracoid bone reaching from the scapula to 

 the sternum, or breast-bone, and the slender clavicle. 



