THE LIZARD, *47 



dorsal extremities of the scapulae, and passing inwards 

 towards the vertebral column : they expand gradually to the 

 dorsal edge, and consist, like the sternum, of partly calcified 

 cartilage, the remainder of the shoulder-girdle being formed 

 of true bone. 



87. The interclavicle, a cruciform bone, having a long 

 posterior limb directed backwards over the ventral surface 

 of the sternum, a short anterior limb, and long lateral limbs 

 passing directly outward, a little anterior to the level of the 

 glenoid cavities. 



88. The clavicles, flat curved bones, articulating in the 

 middle central line with one another, and with the anterior 

 limb of the interclavicle, and passing at first directly 

 outwards, then outwards and upwards to the anterior border 

 of the suprascapula to which they are united by fibrous tissue. 



X. In the fore-limb make out the following : 



89. The general composition of the limb : it consists of 

 a proximal division (skeleton of the brachium, 117 ) con- 

 taining a single bone, the humerus ; a middle division 

 (skeleton of the antebrachium), containing two bones, 

 *a smaller, internal, the radius, and a larger, external, the 

 ulna; and a distal division the manus, consisting of a 

 carpus or wrist, and of five digits. 



90. The position of these parts : the humerus is directed 

 from its proximal or attached end, backwards, upwards, and 

 outwards ; the ulna and radius pass, from their articulation 

 with the humerus, downwards and slightly forwards; the 

 manus has its digits directed forwards and outwards. 



91. If the limb is extended at right angles to the long 

 axis of the trunk, it presents a dorsal and a ventral 

 surface, an anterior or pre-axial and a posterior or 

 post-axial border; the radius is then seen to be pre- 

 axial and the ulna post-axial. In the ordinary position the 



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