372 CHORDATA. ' 
front-limb is greatly developed, and in the caudal vertebra 
of the frog (urostyle), in which the hind-limbs are enlarged. 
Fig. 264.—VENTRAL VIEW oF STERNUM OF THE PIGEON. 
(Ad nat.) 
Manubrium. 
Carina. 
Coracoid Groove. 
Costal Ridge. 
Xiphoid 
Process. 
Posterior Xiphoid 
Process. 
Fontanelle. 
Fig. 265.—THE PECTORAL GIRDLE OF THE PIGEON. 
(Ad nat.) 
Scapula, 
Left Clavicle. 
aay 
Right Clavicle. 
Coracoid. 
Episternum. 
The shoulder-girdle is formed of three elements, the 
clavicle, coracoid and scapula. Of these the clavicle is slender 
and joined to its fellow by fusion with an episternum. The 
