io8 Elementary Zoology. 



In the Rabbit the shoulder-girdle appears to consist of but 

 a single cartilage bone, the scapula. This is a triangular bone, 

 with a median ridge along the outer surface, ending in a 

 process, the acromion. At the distal end of this is a lateral 

 outgrowth of the ridge, termed the metacromion. The end of 

 the scapula forms the glenoid cavity for the articulation of the 

 humerus ; but on the inner side of this articular cavity is a 

 little process of bone (Fig. 49, cr), which is really ossified by 

 two centres quite separate from the rest of the scapula. These 

 represent collectively part of the coracoid of the bird ; but it 

 will be remembered that the coracoid of the bird reaches the 

 sternum. The junction of the scapula with the sternum is 

 effected in the rabbit by the clavicle, a membrane bone, and by 

 certain ligaments. Outside the clavicle, however, fragments of 

 cartilage (dotted in the figure) have been discovered, which 

 seem to be bits of the otherwise missing distal part of the 

 coracoid. 



The sternum is a jointed bone, made up of seven separate 

 pieces, or sternebrse, as they are sometimes called. The first 

 of the series is the longest, and forms the manubrium ; the 

 last is a long slender rod, ending in a cartilaginous plate, the 

 xiphisiernum. 



The fore limb itself has precisely the same divisions as in 

 the other Vertebrata. The hand, however, has five fingers, and 

 the carpus is composed of eight separate bonelets. 



Skeleton of the Hind Limb. 



As is the case with the fore limb, the hind limb consists of 

 a girdle, the pelvic girdle, and of the limb attached thereto. 

 There is, as will be seen, a very close correspondence between 

 the several elements of the two limbs and their girdles. 



The pelvic girdle of the Frog appears to consist of two 

 separate bones, somewhat spoon-shaped, narrow in front, and 

 expanding posteriorly into a flattened and rounded area. The 

 narrow ends of the two are attached to the wide transverse 

 processes of the sacral vertebra. Each of these bones is in 



