Ill 



FORE -LIMB 



The fore-arm is also supported by a single bone, the 

 radio-ulna (Fig. 8, RA.UL ; Fig. 13, B). Its proximal 

 end is concave and articulates with the almost globular 

 condyle of the humerus : the outer or posterior edge of 

 the concavity is produced into a short process, the 



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FIG. 13. Longitudinal sections of the principal long bones of the Frog, (x 2\.) 

 A, humerus ; B, radio-ulna ; C, femur ; D, tibio-fibula ; en. condyle ; /. foramen 

 for artery ; yt. fibula ; hd. head ; m. marrow ; oL olecranon process ; p. bony 

 partition ; ra. radius ; sh. shaft ; ti. tibia ; ul. ulna. 



olecranon or elbow. The distal end is incompletely 

 divided into two articular surfaces, and between these 

 is a groove passing for some distance towards the 

 proximal end of the bone. A section shows that at this 

 end there are two distinct marrow-cavities, indicating 

 that the bone is really double. That this is the case is 



PR ACT. ZOOL. -rp 



