RAN A. 



351 



bears a small cartilaginous rib. The eighth is like the 

 preceding in general structure but is amphiccelous, i.e., it has 

 a concave articular surface at each end. The ninth vertebra 

 has large transverse processes to which is attached the pelvis. 

 Hence this vertebra is called the sacrum. It is biconvex, 

 with a convexity at each end of the centrum. The urostyle 

 is a long bone formed of at least three fused vertebrae. It is 

 hollow^ for part of its length and contains the posterior end 

 of the spinal cord. 



Fig. 248. — Pectoral Girdle of Ran a. 



Episternum. , 

 Omosternum. 



Clavicle. Suprascapula. 



Scapula. 

 Coracoid. 

 Xiphisternum. 

 View with dorsal parts bent downwards. Bone is black and cartilage dotted. 



O 



The presence of this urostyle, the single sacral vertebra 

 and the small number of vertebrae are the important 

 peculiarities of the vertebral column. The vestigial ribs 

 are also to be noted. 



Fig. 249. — Fore-limb of Rana. 



Phalanges of 

 Digits. 



I^^W/]/^ Metacarpals. 



Carpals. 



Humerus. 



Radio-ulna. 



Note fusion of radius and ulna and absence of pollex, a metacarpal only remaining. 



The peripheral (or appendicular) skeleton consists of 

 the two limb-girdles and limbs. These are constructed on 

 the pentadactyle type (see page 420). The shoulder-girdle 

 (pectoral girdle) consists of paired clavicles and coracoids 



