174 VERTEBRATES 



Find the vertebrae. How many? At the posterior end 

 find the pecuHar flat branched bone, the urostyle. Separate 

 the fifth vertebra from the others and study the bone. Find 

 the main body or centrum, the neural arch tlirough which 

 the spinal cord passes, and the processes on either side. 

 How many processes are there, and of what value are they ? 

 Compare the vertebrae with the corresponding bone of the 

 vertebral column of the fish. Draw lateral and end views. 



(5) The Limbs. — a. Study the shoulder or pectoral 

 girdle. Trace out the sternum, or breast bone, the flat shoul- 

 der blade, or scapula, the collar bone, or clavicle, and the 

 coracoid by which the pectoral arch is attached to the ster- 

 num. Note how the clavicle, scapula, and sternum are 

 braced with reference to one another. Draw the shoulder. 



(6) Observe the bones of the fore arm. The humerus, 

 the long bone joined to the shoulder, the radius, the larger, 

 and the ulna, the smaller of the bones of the fore arm grown 

 together ; the carpus, or wrist bones ; the metacarpus, a 

 transverse row of cylindrical bones ; the phalanges, or fin- 

 gers ending in the smaller tips of the digits. Draw arm. 

 Study the joints, move them back and forth to find the free- 

 dom of movement, and note the method of articulation. 

 Sever the tissue at the elbow joint and study it. Note the 

 white ligaments which are modified from the covering of 

 the bones. Study their attachment and the method of 

 crossing the joint. Are these ligaments elastic? Note the 

 modification of the bones at the joints. Of what value is 

 it? Note the covering of the bones at the ends. Of what 

 value is it? 



Draw the joint showing the things referred to. 



The joint at the shoulder is called a ball and socket joint; 



